WSET Unit 2: Wine Production > Viticulture > Flashcards
Viticulture Flashcards
Pierces disease is spread by what?
Glassy- winged sharpshooter (a fungal disease)
Alternative Viti practices
Integrated Pest Management, Organic, Biodynamic
Harvesting- getting ready
Estimating the crop (sufficient tank space). Checking and cleaning equipment and machinery. Tanks clean and ready to use. Oenological products (yeasts, sulphur, enzyme, etc)
Harvesting- Machine versus hand- factors to consider
Quality, speed, economics, feasibility
Harvesting- machine
Speed, grapes @ peak: cheaper labor cost, cool night.
Damage oxidation, no selection, cost of machinery, flat land, trellis system.
Harvesting- manual
Less damage, more selective, slopes, less $ for equip.
High labor costs (10x machine) slower. For sparkling wine, carbonic Maceration (while bunches): Tokaji, beernauslese, Trockenberenauslese, (selection of grapes) required by law.
Harvesting- transport and reception
Use shallow picking containers Less transfer between containers Less dumping heights Refrigerated trucks Minimise delay before processing
Harvesting- transport and reception (Oxidation)
Browning loss of aroma
CO2/ Nitrogen blanket, potassium Metabisulphate, harvest @night, min delay.
Harvesting- transport and reception (Microbial Growth)
Eliminate rotten grapes, clean equip, berry integrity, min delay
Harvesting- transport and reception (contamination)
Rain. Leaves and stalks. MOG (material other than grape). Soil.
Key questions for grape processing
Sorting, de- stemming, crushing, type of press, amount of CO2, must treatments.
De- stemming
Tannin control and ease of processing.
Egrappoir= destemming machine
Most grapes are de- stemmed
Not for sparkling wines and carbonic Maceration
Not required for machine harvested grapes
Destemming- Pros
Prevent release of Phenolics, herbaceous flavors, MOG.
More efficient pressing.
Remove water and potassium (absorb color and alcohol).
De- stemming: Cons
Whites: Slower pressing and drainage (not for fine whites).
Reds: compaction of pomace cap; tannins and colour
Harvest date: grape ripeness
Sugar
Acid
Health
Phenolic Ripeness
Harvest date: Agrochemicals
(Fungicides, Insecticides, Herbicides, etc)
Withholding period.
Fermentation and health problems eg Sulphur= H2S (Hydrogen Sulphide). Copper= brown haze, toxic copper salts in wine.
Harvest date: Weather
Rain= dilution, grape swelling, bursting
Hail
Harvest date: Availability of Resources
(Human and mechanical)
Legal restrictions
Grape maturity
One of the most decisive factors in determining wine quality and style.
Physiological changes- Phenolics and taste biochemical changes- sugars and acids
Vine Species
For fruit: Vitis Vinifera
For Rootstocks: Vitis Riparia, Vitis Rupestris, Vitis Berlandieri
What part of the vine do nematodes attack?
Vine roots
Besides preventing destruction by phylloxera, why might a producer choose to graft vines?
Nematodes or other pests; vineyard characteristics. Example: grafting naturally prolific vines like Sav Blanc to a low- vigor rootstock to reduce green/ unripe flavors
What weather patterns can create a marginal climate?
Risk of early or late frosts, extreme temps, heavy rains @ harvest time, heavy storms or hail during growing season. Examples; Champagne (frost), Bordeaux (rain), Mendoza (hail)
What three methods are used to prevent frost?
Wind Machines
Smudge Pots
Aspersion Systems
What is Coulure?
Floral abortion. The term for when an unfertilised blossom is shed, therefore there is no grape.
This rootstock is particularly recommended for acid soils?
3309C (Couderc)
Parentage Riparia X Rupestris
This rootstock is suitable for use in Northern vineyards. Poor Potassium (K) uptake.
5C (Teleki)
Parentage: Riparia X Berlandieri
This rootstock fruits well and is used in the South of France.
99R (Richter)
Parentage Berlandieri X Rupestris
1103P (Paulsen)
Parentage Berlandieri X Rupestris. Good for parentage in dry and stony conditions. Deep or semi- deep rooting systems. Good vigor, good resistance to phylloxera, chlorosis and drought. Better lime resistance than straight Rupestris. Likes poor, dry, average compactness soils. Warm climate rootstock. Saline resistance.
Fercal
Parentage Berlandieri X Vinifera. Good resistance to lime and chlorosis, likes dry, shallow, calcareous soil. Very high like tolerance. Too much K application will lead to Mg deficiency.
41B (Millardet Et De Grasset)
Parentage Berlandieri X Vinifera. Good resistance to lime and chlorosis, likes dry, calcerous soil. High lime tolerance. Used in champagne and charentes. Some phylloxera suspectibility. Good fruiting, good uptake of Mg.
333EM (Ecole de Montpellier)
Parentage: Berlandieri X Vinifera. Good resistance to lime and chlorosis, drought and phylloxera. High lime tolerance. Champagne, charentes, midi. Can cause Coulure.
Dog Ridge
Parentage: Vitis Champini. Important for regions with severe nematode problems, but tends to be extremely vigorous and unsuitable for high quality grapes, likes poor soils, low lime tolerance and low tolerance of phylloxera and drought.
This is the most popular rootstock in Europe.
SO4 Selection Oppenheim
Parentage: Riparia X Berlandieri
Rootstocks with this parentage are vulnerable to Coulure
Riparia X Berlandieri
Name two rootstocks good for use in areas with serious nematode problems.
Schwarzman (Riparia X Rupestris) and Dog Ridge (Vitis Champini) of the two, schwarzman is more versatile.
This rootstock is a high vigor Mediterranean rootstock, sensitive to Coulure.
Rupestris du lot parentage: Vitis Rupestris
This rootstock, heavily promoted by US Davis, turned out to be vulnerable to phylloxera is no longer widely planted in California.
AXR1 (aka ARG1)
Parentage: Vinifera X Rupestris
420A (Millardet et de Grasset)
Parentage: Riperia X Berlandieri. Surface or semi- surface; good rooting, high chlorosis resistance. Medium lime tolerance. Good scion affinity, good phylloxera resistance. Good for quality vineyards.
5C (Teleki)
Parentage: Riperia X Berlandieri. Surface or semi- surface. Good rooting. High chlorosis resistance. Medium lime tolerance. Good scion affinity, good phylloxera resistance. Suitable for quality vineyards in Northern regions. Poor Potassium (K) uptake.
5BB (Teleki Selection Kober)
Parentage: Riparia X Berkandieri. Surface or semi- surface. Good rooting. High chlorosis resistance. Good scion affinity, good phylloxera resistance. Medium lime tolerance. If fertile soil, not to be planted with varieties sensitive to Coulure. Poor uptake of K, Mg
SO4 Selection Oppenheim
Parentage: Riperia X Berkandieri. Surface or semi- surface. Good rooting, high chlorosis resistance. Good scion affinity, good phylloxera resistance. Medium lime tolerance. Very fruitful. Most popular rootstock in Europe. Poor uptake of Mg- Coulure and stem atrophy. Several clinal variations available.
125A Kober
Parentage: Riperia X Berlandieri. Surface or semi- surface. Good rooting. High chlorosis resistance. Good scion affinity, good phylloxera resistance. Medium lime tolerance. Accepts wide range of soils. Not recommended for varieties sensitive to Coulure.
99R (Richter)
Parentage: Berlandieri X Rupestris. Good for planting in dry and stony conditions. Deep or semi- deep rooting systems. Good vigor, good resistance to phylloxera, chlorosis and drought. Better lime resistance than straight Rupestris. Fruits well. Used in the South of France.
110R (Richter)
Parentage: Berlandieri X Rupestris. Good for planting in dry and stony conditions. Deep or semi- deep rooting systems. Good vigor, good resistance to phylloxera, chlorosis and drought. Better lime resistance than straight Rupestris. Likes deep, poor, clay- calcerous soil. Good rootstock for dry regions. Port uptake of K and Mg.
140RU (Ruggieri)
Parentage: Berlandieri X Rupestris. Good for planting in dry and stony conditions. Deep or semi- deep rooting systems. Good vigor. Good resistance to phylloxera, chlorosis and drought. Better lime resistance than straight Rupestris. Likes poor, dry soil. Suitable for Mediterranean vine growing countries.
Schwarzman
Parentage: Riperia X Rupestris. Halfway between surface and deep rooting. Average vigor, grafts well, good affinity with scions. Good phylloxera resistance. Poor resistance to chlorosis and drought. Low lime tolerance. Likes deep, moist soil. Ideal in areas with serious nematode problems.
161- 49C (Couderc)
Parentage: Riperia X Berlandieri. Surface or semi- surface. Good rooting, high chlorosis resistance. High lime tolerance. Good scion affinity, good phylloxera resistance. Widely used in France, Switzerland, Germany. Good fruiting. Good for acid soils.
Riparia Gloire de Montpellier
Parentage: Vitis Riperia. Low vigor, low resistance to drought, low lime tolerance. Likes humid cool, fertile soil. High tolerance to phylloxera. Prefers moist soils. Sensitive to compact soils.
Rupestris du Lot
Parentage: Vitis Rupestris. High vigor, low lime tolerance. Likes deep, poor soil. A high vigor Mediterranean rootstock, sensitive to Coulure and compact soils.
AXR1 (aka ARG1)
Parentage: Vinifera X Rupestris. Has some of the lime tolerance of Vinifera, but unfortunately shows inadequate tolerance of phylloxera- extensive planting in California proved to be a very expensive mistake. Easy to graft, high yields, high lime tolerance.
3309C (Couderc)
Parentage: Riperia X Rupestris. Halfway between surface and deep rooting. Average vigor, grafts well, good affinity with scions. Good phylloxera resistance. Poor resistance to choloris and drought. Low lime tolerance. Fruits well. Widely used in France, Switzerland, Germany. Particularly recommended for acid soil.
101- 14 (Millardet et de Grasset)
Parentage: Riperia X Rupestris. Halfway between surface and deep rooting. Average vigor, grafts well, good affinity with scions. Good phylloxera resistance, poor resistance to chlorosis and drought. Low lime tolerance suitable for production of quality wines.
This warm climate rootstock is saline resistant.
1103P (Paulsen)
Parentage: Berlandieri X Rupestris
What is the species of grapevines that are used in wine production.
Vinifera
Where is Vinifera a native species of grapevine?
Europe and Western Asia
Berlandieri X Vinifera
Rootstocks with this parentage are used in champagne and charentes, have good resistance to lime and chlorosis, but some have poor resistance to phylloxera.
This rootstock has very high lime tolerance.
Fercal.
Berkandieri X Vinifera
Vine Anatomy
Shoots, leaves, tendrils, flowers and berries, buds, one year wood (cane, spur), permanent wood, roots
Vine Varieties
Vines belong to the same variety if their origin can be followed back, through a series of cuttings to the same original parent plants. Varieties can only be reproduced by taking cuttings from an existing plant. Varieties cannot be reproduced by planting the pips (seeds) of a grape. If the pip of Chardonnay is planted, the vine that grows from it would not be Chardonnay
Clones
Select specimens of a specific variety are propagated for their characteristics that have emerged through the generations by mutations.
Crossing
Any variety that is grown from seed whose parent vines were both v. Vinifera
Hybrids
Any variety that is grown from seed whose parent vines came from different vine species
Key questions for harvesting
When
Forecasting
Preparing
How (manual vs machine)
The Growing Environment
In order to grow and photosynthesis, a vine needs access to CO2, water, sunlight, heat and nutrients. CO2 is never in short supply but the availability of the others affects how a vine grows
Temperature
A vine needs: average temperature in the growing season b/ween 16c and 22c to grow and photosynthesis. Different varieties require different amounts of heat to thrive.
Factors with temp: latitude, alt, ocean currents, fog, soil, aspect, continentality, diurnal range
Hazards linked to temp: winter freeze, frost, mild winters, excessive summer heat
Rootstocks
The pest phylloxera is fatal to v. Vinifera. The only reliable solution is to graft v. Vinifera onto non- vinifera rootstock that can resist this pest.
This rootstock likes, poor, dry soil, has high lime tolerance, and is suitable for Mediterranean vine growing countries
140RU (Ruggieri). High lime tolerance.
Rootstock with this parentage is good for planting in dry and stony conditions. Good resistance to chlorosis and drought and tolerates lime better than straight Rupestris.
Berlandieri X Rupestris
What is meant by “Hen and Chick” when referring to a grape cluster?
Small and large berries on the same cluster, greater skin to juice ratio.
What is the difference between a macroclimate, a mesoclimate and a microclimate?
Macro- particular region
Meso- particular vineyard
Micro- vine itself
What is parral?
Training the grapes on high trellis
What attributes does a balance vine possess?
Correct relationship of the soil/ root system and number of leaves it can support
What is the difference between a species, a clone and a variety of grape?
Species- particular group of grape vines (v. Vinifera)
Clones- vines descended from a single parent
Variety- subspecies of grape (like Chardonnay)
Mediterranean climate- characteristics
Maritime climate (warm summers, mild winters) but most of the rainfall occurs in winter. Particularly suited to viticulture. California, Chile, Sth Africa, Sth Oz, Mediterranean shores.
What is photosynthesis?
Photosynthesis is the process by which chlorophyll in the leaves uses sunshine to convert CO2 into sugar and oxygen.
What is the optimal temp and weather conditions for photosynthesis to take place?
Temp between 21c (70F) and 29.4c (85F), sunny
What does “stomata” describe?
Stomata are the openings on the underside of the leaves
What is “respiration”?
Respiration is the process by which sugars are broken down and used by by the vine as an energy source.
What is “translocation”?
Translocation is the process by which materials are moved from one area of the plant to another.
What is the microclimate if a grapevine?
The microclimate of a grapevine is the environment within and directly surrounding the canopy.
What is the mesoclimate of a grapevine?
The mesoclimate of a grapevine is the typical weather experienced in a particular vineyard.
What is the macroclimate of a grapevine?
The macroclimate of a grapevine is the climate of the overall region.
What happens during winter pruning?
The removal of portion of the previous season’s growth so that the vine maintains a desired shape and size.
What occurs during shoot thinning?
The removal of excess shoot growth during the Spring.
What is summer hedging?
Summer hedging refers to the removal of the cane’s growing tips in order to partition carbohydrates.
What does shoot devigoiration mean?
Shoot devigoiration is the natural slowing of shoot elongation.
What is shoot positioning?
Shoot positioning is the arranging of shoots so that the canopy has good sunlight penetration and good air circulation to all leaves.
Describe leaf removal
Leaf removal is the systematic removal of leaves in the fruit zone so that the sunlight strikes the clusters, ensuring optimal pigment and Flavor development. Considered a band- aid fix for poor canopy management.
What is leaf roll?
Leaf roll is a viral disease turns vine leaves gold and red, rolls the blade downward and announced the delayed crop ripening/ reduced yields.
What is the remedy for leaf roll?
The only remedy for leaf roll is vine removal.
What is fan leaf?
Fan leaf is viral disease that is responsible for unusual growth patterns in the vine, such as short internodes, abnormal branching, malformed leaves that look like fans, small clusters, poor fruit set, and seedless berries. Vine will have a shorter life span.
How is fan leaf spread?
Fan leaf is a virus spread by the nematode soil pest xiphinema index.
What is esca disease?
Esca (aka Black Measles) is a fungal disease that is a problem in warmer climates where it can kill vines suddenly in hot weather.
What is eutypa dieback?
Eutypa dieback is a fungal infection caused by eutypa late. Occurs more often in Mediterranean climates. Fungus enters through pruning wounds, realising a toxin that stunts the shoots and cups the leaves, eventually killing the infected cane. Also known as “Dead arm”.
How is eutypa dieback treated?
Eutypa Dieback can be treated by applying fungicide to pruning wounds.
What is black rot?
Black rot is a fungal disease native to NE N. America that attacks the vine in mild, wet weather. Starts as a black spot on the shoot, leaves or berries then spreads along vine tissues. Can be controlled by fungicides.
What is pierce’s disease?
Pierce’s disease is a bacterial contamination of the host vine resulting in premature leaf fall.
What is the carrier of Pierce’s disease?
Several types of sharp- shooter or leafhoppers. Glassy winged sharpshooters are the best known example.
What is crown gall?
Crown gall is a bacterial disease that causes large tumours to grow on the trunk of the vine. The tumours girdle the vine, strangling the portions above it so that the vine withers and dies.
Define the term “cultivar”
Plants sharing common characteristics. Synonym and technical for varietal.
What soil pest spreads fan leaf virus?
Nematodes, xiphinema index
Which are the inputs and products of photosynthesis?
From sunlight, input carbon dioxide and water/ output, sugar and oxygen
How does phylloxera damage a vine?
Causes galls in the root system during the root- feeding phase of the phylloxera life cycle.
What is a trellis system?
It is a network of stakes, posts, support wires and catch wires that position the vines vegetative growth in space.
What does the term “third leaf” refer to?
The first crop of grapes that are harvested for the use of wine making. Generally when the vine is 3 yrs old.
What is the average age of maturity for a grapevine?
6 years
When does a grapevine decline in vine vigor?
After 20 years
What does the term “mutation” refer to in wine production?
A vine that has developed different characteristics through imperfect reproduction of cells as it grows.
Name two mutant strains of Pinot noir.
Pinot Blanc, Pinot Gris
What is bud break?
The start of the growth cycle of the vine. Average air temp must be around 10c shoots appear.
When does flowering take place? What weather is ideal for flowering?
Flowering takes place 40- 80 days after bud break. Warm, dry weather is best.
What does “berry set” refer to?
The result of fertilisation that marks the transition from flower to berry.
What does “verasion” refer to?
The stage in the growth cycle after berry set, when the red grape skins begin to change color, grapes are softer, sugar levels increase, acidity decreases.
What does “ripeness” mean?
Ripeness refers to the sunshine- derived sugar levels.
What does “maturity” mean?
Maturity refers to the flavors that develop in the grape due to physiological changes. These include an increase in pH level, an increase in K level, a softening of grape tannins, or the lignification of the seeds inside the grape berries.
When does pruning take place?
Pruning is done during the winter months after the first frost, after leaf fall.
Head grafting
The practice of changing an established vineyard from one varietal to a more profitable varietal without having to replant the entire vineyard.
Graft/ grafting
Viticulture technique where the sections of two different plants are joined so that their tissues unite.
Field graft
Grafting done in the vineyard
Crossing
A vine variety created by cross- pollinating two different varieties within the same species
Cordon
An extension of a vine’s trunk
Bush training
Training the grape vine as an independent plant w/out a trellis system
Bleeding
A.k.a “Weeping” the first sign after winter that the vine is coming out of dormancy. Generally occurs in Feb (N. Herm); August (S. Herm)
Bench Graft
Grafting done in a nursery
Aspersion
Spraying the buds or grapes with water to protect against late frosts or freezes the water turns to ice which protects the buds from colder temperatures.
Ampelography
The study of grape vines
Scion
Section of plant material grafted onto a rootstock
Translocation
Movement of sugars, nutrients and water from one part of the grapevine to another pest
What does the term “variety” refer to in wine production?
A sub- species of grape, Chardonnay would be an example of this.
What is esca?
A fungal disease that causes the grapevine wood to soften and rot
Hybrid
A creation of a new variety by cross- pollinating two vines of different species.
Hectolitre
26.418 Gallons or 100 Litres
Hectare
2.471 Acres
Viral and bacterial diseases
No cure
Harvesting
Machine Harvesting: Fast, can work at night, lack of selection, only works on flat or gentle slopes.
Hand harvesting: Essential when whole bunches are needed and when picking botryitised grapes, less damage, possible on all terrains, requires a skilled workforce that is not always available
Climate Classification
Temp range: cool, moderate, warm, hot
Types of climate: continental, maritime, Mediterranean
Water- a vine needs
Sufficient water to support photosynthesis and mild water stress to promote ripening. The amount of water needed depends on the vine’s needs, which rise with the temp.
Water- sources of water
Rain, irrigation (drip, sprinkler, flood)
Water- hazards associated with water
Too little: drought, poor ripening and vine death
Too much: excessive growth, shading and poor ripening, fungal disease, disrupts flowering and fruit set. Hail.
Sunlight- a vine needs
Sunlight in order to be able to photosynthesis, convert water and CO2 into glucose for growth and ripening grapes. More sunlight= more sugar production
Sunlight- factors associated with sunlight
Seas and lakes, latitude, aspect
Sunlight- hazards associated with sunlight
Too little sunlight can give under ripe grapes with tart flavors. Too much sunlight can cause sunburn and give grapes a bitter taste
Temp- a vine needs
Avg temp in the growing season between 16c and 22c to grow and photosynthesis. Different varieties require different amounts to survive.
Temp- Factors associated with temp
Latitude, altitude, ocean currents, fog, soil, aspect, continentality, diurnal range
Temp- hazards linked to temp
Winter freeze, frost, mild winters, excessive summer heat
The growing environment
In order to grow and photosynthesise, a vine needs access to CO2, water, sunlight, heat and nutrients. CO2 is never in short supply but the availability of the others affects how a vine grows.
Crossing?
Any variety that is grown from seed whose parent vines were both v. Vinifera
Hybrids?
Any variety that is grown from seed whose parent vines came from different vine species
Continentality?
How the temp varies in a year
Clones
Slept specimens of a specific variety are propagated for their favourable characteristics that have emerged through the generations of mutations.
Vine Varieties
Vines belong to the same variety if their origin can be followed back, through a series of cuttings, to the same original parent plant. Varieties cannot be reproduced by planting the pips (seeds) of a grape. If the pip of a Chardonnay grape is planted, the vine that grows from it would not be Chardonnay.
What definitions apply to the term clone?
Clone can be a verb meaning to create an exact copy of a grape vine through cuttings. Example: clonal selection. Clone can be a noun describing exact generic copies of a grape, or mutations of a grape or mutations of a grape. Example: Pinot Noir, Gris, Blanc, Meunier
In which areas of the world is phylloxera not currently a problem?
Chile, S/ OZ, most of Argentina, Hungary
What spreads leaf roll virus?
Mealy bugs
What are the three major soil nutrients required by grapevines?
Nitrogen, Phosphorus, Postassium
What are the differences between sustainable, organic and biodynamic viticultural practices?
Sustainable: be nice to the land (for the most part)
Organic: love the land, increase biodiversity, protects the environment.
Biodynamic: treat the planet as an ecosystem
What is a graben?
A grave- like trench framed by 2 vertical uplifts
Fungal Diseases
Sprays
What spreads fan leaf virus?
Nematodes
Yield
Measured in weight of grape or volume of liquid per area. Hard to predict due to annual variation in weather and disease. There is not a direct correlation between yield and fruit quality.
Tech used: Pruning, Green Harvesting
Diurnal Range
How temps vary during a day
Soil- composition
Soil particles, stones and rocks, humus, plant nutrients
Soil- soil and water
Water is held in the soil and underlying rock. The amount of water available to the vine affects its growth. The best soils retain only enough water to sustain the vine needs.
Soil- soil and nutrients
Vine only needs very small amounts of nutrients. Too much and the vine will grow vigorously; too little and the vine is unable to grow properly.
Two factors considered when assessing ripeness of the grape.
- Phenolic Ripeness (skins, pips)
2. Sugar Ripeness
Continental Climate
Continentality: High
Rainfall: Usually Low
Growing Season Temp: Can be cool, moderate, warm or hot
Growing season sunlight: usually very sunny
Sunlight- why needed
Wine needs sunlight to photosynthesis, convert water and carbon dioxide into glucose for growth and ripening grapes. More sunlight- more sugar production
Growing Environment
To grow, vine needs carbon dioxide, water, sunlight, heat and nutrients.
Vine varieties- crossing
Any variety grown from seed whose parent vines where both Vitis Vinifera
What is marl?
A soil mixture of clay and chalk. Pinot Noir grows best in this soil.
Nematodes?
Suitable rootstock and sanitise soil
Birds and mammals
Physical barriers
Insects and arachnids
Sprays, natural predators
What is chlorosis?
A condition in which the vine produces in sufficient cholorphyll. Yields fail and leaves turn yellow as a result of reduced photosynthesis usually caused by excess heat, transpiration, lack of water, lack of ironin the soil, disease or a combination there of.
Define Transpiration
Similar to perspiration, in which water is evaporated through the leaf of the vine.
What stops vines from developing deep root systems?
Irrigation
What is another word for floral abortion where a non- fertilised blossom is shed?
Coulure
Pudding stones or gallets are storage heaters for which area/ region?
Rhone
Ferrous sulphate helps treat what kind of deficiencies in the soil?
Mineral
True or False:
The more dense the planting, the more stress on the vine, and the better the fruit
True
What is the most common training system in the world?
VSP, Vertical Shoot Positioning
Name 3 major disease brought over the EU from the US
Phylloxera, Oidium, Personospera
What is the mixture comprised of copper sulphate and lime that prevents/ kills downy mildew called?
Bordeaux Mix
What geological feature(s) and viticulture efforts deter the spread of phylloxera?
Sandy or saline soils. Example: South Australia; geographical isolation, Example; Chile (Desert to N. ocean to W. Andes to E. Arctic to S) Quarentine procedures, grafting
What is millerandage?
Small seedless grapes in a bunch. The result of uneven berry set.
Describe cloning
A sexual process. Cuttings are taken from individual vines and allow it to grow into a new vine. Requires genetic instructions to be copied every time a new cell is created. Mutations can occur giving slightly different versions of a variety. May select clones with desired qualities for future propagation.
Homoclimes
Sites whose climate closely match that of the world’s great v/yards or regions.
What is a pergola?
A form of overhead vine training used in Italy
What is Personospera?
Downy mildew, a fungal vine disease
Soil and nutrients
Vine only needs very small amounts of nutrients. Too much and the vines will grow vigorously, too little and the vines is unable to grow properly.
Soil and water
Water is held in the soil and underlying rock. The amount of water available to the vine affects its growth. The best soils retain only enough water to sustain the vine’s needs.
Composition of soil
Soil particles, stones and rocks, humus, plant nutrients.
Warm Mediterranean climates
Chateaunerf- du- pape, Napa Valley
Moderate Mediterranean Climates
Chianti, Carneros
Warm Comtinental Climates
Auckland
Moderate Maritime Climates
Bordeaux, Rias Baixas
Cool Maritime Climates
Muscadet
Hot continental climates
La Mancha, Port
Warm Continental Climates
Ribera Del Duoro, Mendoza
Moderate Continental Climates
Burgundy, Central Otago, Barolo
Cool continental Climates
Champagne, Mosel
Maritime Climate
Continentality: Low to Medium
Rainfall: Usually Medium to High, spread throughout the year
Growing season temp: usually cool or moderate
Growing season sunlight: usually cloudy
Mediterranean Climate
Continentality: Low to medium
Rainfall: Usually low to medium mostly failing in the winter
Growing season temp: usually moderate or warm
Growing season sunlight: usually sunny (unless other effects, such as fogs)
When is the first yield and make it be used in production of quality wine?
Year 3. May not be used in production of quality wine in EU.
Soils and typography- effects
Soil: water retention (absorption and drainage. Heat retention, nutrients and minerals)
Topography: Steepness and direction affect drainage, air circulation and exposure to the sun
Vines grow best at which latitude?
Between 30- 50
Define Verasion
Word used by English speakers for that intermediate stage of grape berry development which marks the beginning of ripening, when the grapes change from the hard, green state to their softened and coloured form.
Parts of a grape
Pulp: water, sugar, acids (tartaric and some Malic)
Skins: colour, tannin and Flavor (esp. In area immediately underneath the skin)
Pips and stems: high levels of tannin
Managing vigour, ripeness and yields
General techniques: pruning: winter pruning (back to cane and spur), summer pruning (to provide sunlight)
Training: bush trained, vertical shoot positioning, big vines
Vigour
A vines vigour is measured by the number of shoots and leaves it grows in a season. Grape growers need to limit shoot growth and folds the vines efforts on fruit ripening.
Techniques used: planting density, pruning training and trellising, rootstocks, cover crops.
True or false:
There is no cure for a vine affected by Pierce’s Disease.
True
Another name for permanent wood is?
Cordons
In what season is pruning and important way of managing yield?
Winter
Natural reproduction w/two varieties of the same species is called?
Crossing
What is the main difference between a Maritime and Mediterranean climate?
Most of the rainfall occurs in the winter for the Mediterranean climate.
Phenolic ripeness involves what part of the grape?
Skins and pips
What enables noble rot?
Meeting of warm air and cold bodies of water or presence of shallow lakes.
What affects can mountains have on the weather?
Mountains may have rain shadow effects, protecting vineyards from rain or can be source of cold winds.
What are canes?
One year old wood on a vine that has between 8 and 15 buds
What is a spur?
Cane that is pruned short leaving 2 or 3 buds
What is must weight?
Juice’s density
What is acetobacter?
Wild yeasts on outside of grape skin. Will turn into vinegar in presence of oxygen.
What is a hybrid?
Marriage between two different vine species. Achieved by artificial evolution.
Currents
Locations and effects
Alaska- cold Humboldt current (Chile)- cold Benguela current (Sth. Africa)- cold Gulf Stream (Nth West Europe)- warm
Continental Climate- Characteristics
- Middle of a landmass
- Extreme temps in both summer and winter
Name 2 of the 5 vineyard pests w/ effect and treatment
- Grape Moths (Cochylis, Pyralis and Eudemis)- Attack buds and grapes, insecticides
- Red/ Yellow Spider Mite- infects leaves/ decreasing vegetation growth, sprays
- Phylloxera
- Nematodes- attacks roots, difficult to cure, prevention is the key.
- Birds and Animals- consume grapes. Netting/ fencing
Define Training
Determines the shape of the vine, by positioning the shoots to display leaves and fruit. Most common system is VSP. Alternatives include pergolas and untrained bush vines.
Define spur pruning
Large number of short (two- or- three- bud) spurs are retained. Vines with a large amount of perm wood tend to be more vigorous than replacement- cane pruned vines
Define replacement cane pruning and describe when it would be used?
One (or more) long canes with up to 15 buds are retained. By minimising the amount of perm wood (and the vines carbohydrate reserves), the vines vigor is restricted, so this system helps to limit yields.
Describe pruning
Determines the number and location of shoots, spur, in which a number of short two- or- three- bud spurs are left on the vine and replacement cane, where one or more longer canes, each of 8 to 12 buds are left.
Parts of a vine- name 7
Roots/ rootstock Trunk/ arms/ cordons- permanent wood Cane/ spur- last year's wood Nodes/ buds (8 to 15 per cane) Flowers/ fruit/ berries Leaves
Pierce’s Disease is spread by?
Glassy winged sharpshooters
Maritime climate- characterisitics
Warm summers
Mild winters
Crossing?
Variety resulting from cross- pollination of 2 different varieties of the same species (eg 2 v. Vinifera)
Hybrid?
Variety resulting from cross pollination of 2 different species
3 forms of protection against Spring frost
- Smudge Pots- create smoke that acts like blankets to keep the heat in
- Wine Machines- drawn in warm air from above to keep the temp @ ground level above freezing point
- Aspersion system- sprinklers spray water so that insulating coat of ice protects the shoots
Marginal climates- example regions and risks
- Opposite of stable climate
- Vintage become important as quality will vary from time to time
- Examples are champagne, Tasmania (just suitable), Bordeaux and hunter valley (risk of heavy rainfall @ harvest), Burgundy, Canada (susceptable to frost), Mendoza, Barolo (susceptable to hail)
What is Cataba?
Also Catawba, North Amercian Vitis Labrusca Grape
Effects of mountains on viticulture
Rain shadow (eg Voges Mts Protect Alsace) Source of cold winds (eg Mistral in Rhone Valley) Temps drop w/increased altitude- (eg Salta, Argentina and Orange, Australia)
Effects of rivers on viticulture
Rivers- less likely to suffer frost damage due to movement of water
Warm air/ cool bodies (Tokaji/ Sauternes)- Mists are created which encourages noble rot
Shallow Lakes (Neusiedlersee in Austria)- Similar to above
Mealy Bugs Spread what?
Viral disease
Powdery/ downy mildew can be prevented by?
Spraying Sulfer
Yield management factors and effects
Effects: excessive yields results in the grapes failing to ripen properly as the sugars in the leaves are shared among to many grapes, high rainfall/ excessive irrigation can give large crops or bloated/ flavourless grapes and resulting wine will lack character.
Factors: # of vines per hectare, # buds to vine, # of shoots, # of clusters to shoot, # of berries to cluster
Weight of berries: green harvesting- pick out excess bunches @ Verasion
Site selection
- Ripening
- Yield (commercial value)
- Quality
Most site selection reasoning is commercial…..
It is great to want to make wines for esoteric reasons, but eventually you have to make money. Plant where there have been commercial crops (ie Tobacco in King Valley)
Jules Guyot
1807- 1872
French Agronomist who devised the vine- management systems predominant in Bordeaux vineyards
Jules- Emile Planchon
1823- 1888
French botanist who first identified phylloxera
Rudolf Steiner
1861- 1925
Austrian philosopher, scientist and founder of the biodynamic movement
Maria Thun
1922- 2012
German biodynamic farmer and key figure in devising the sowing and planting calendar following the moon’s phases
Varieties planted are….
- Dictated by climate and commercial considerations
- Market force of supply and demand
- Legislation
On a bad vigor site…….
You need more vines to make up for quality
Scott Henry
Mainly used in cold regions. Scott Henry everything goes up taller and straight down
Summer Training
Trimming> green harvest
Two different deficiencies
Macronutrients
Micronutrients
Weed Control
Cultivation
Ground cover= crop cover
Herbicides
Mulching- very expensive
When cant France irrigate?
After July (they believE it is due to quality)
What does Regulated Deficit Irrigation put pressure on?
Progeny (grapes)
Lutte Raisonee
“We will try our hardest to not use the bad stuff, but we will if we have too”
Harvesting
Planning, Cleaning and drinking beer
Brix
Baume
10 g/L
18 g/L
Baume
1 degree of Baume is 1% alcohol
Size of bin depends on quality
5 kg bins high quality: Bordeaux, 500 kg bins high yielding: Riverland Chardy
Clarification
Is clearing something up
Decantation
Tank, solids got to the bottom, rapid and constant
Flotation
Muck goes to the top of the tank, can put vacuum in
Deacidification
Germany and Loire- used a lot
Flash detente/ Flash expansion
Shatters the grape cells, so you get grape pulp. Very much like thermovinifcation
Green Concrete
Long term use of agrochemicals which leads to a lack of health in the soil
Organics/ Biodynamics
Organics- What you do, Biodynamics- is what you do do
Irrigation- critics
Strain on global water resources and impact on eco systems
Primary Irrigation
Used in hot or arid zones
Supplementary Irrigation
To help from drought or lack of water
Fertigation
Using manure in the drip lines to help disperse it
Increasing Metamorphism
Shale, when under pressure (via both heat and friction), will transform into slate, and with greater pressure, into schist, and finally gneiss. Gneiss (along with granite) is one of the hardest rocks out there.
What is shale?
Shale is a composite of mud and clay, that’s been compacted into a solid.
What is clay?
Clay is a sediment, a mixture of sand and the tiny decay of other silica-based and aluminum-rich minerals that break down in water.
There are only three types of rocks:
igneous rocks, which are cooled off magma; sedimentary rocks, which are compressed sediment; and metamorphic rocks, which are other rocks that are pressed and heated into a new form.
The forces of erosion
Shorelines, wind, water and sun — are startlingly powerful, and are key to rock transformation.
Did you realize that limestone will……..
Eventually become marble under metamorphic pressure?!. Hence why there are marble factories in Burgundy.
What is limestone?
Basically: very, very old seafood. Limestone is a solidified accumulation of lime, that is to say calcareous skeletal remains (shells, coral, plankton, or old algae). In the case of Kimmeridgian limestone — that great sculptor of Chablis, the finest white wine on earth — it is encrusted with fossils from sea creatures such as Exogyra virgula and Ammonite.
Chalk
is limestone, but it’s special: it’s a white or gray colored surprisingly pure variant of limestone that’s up to 99% pure lime. It’s made of microscopic nanofossils, so tiny they can condense into such a dense lime form.
Marl
Is an unstable concept. It’s a variable composite of lime or clay. You can’t have all of both: it is either nearly all lime, or nearly all clay, with a bit of the other. It may be solid or pliable. (No wonder no one understands this). If it’s hardened, you can call marl a marlstone. If mud is hardened, you can call it mudstone.
Tufa/ Tuffeaux
Tufa forms in a freshwater environment instead of the deep sea; think of Yellowstone’s hot springs. Tufa are found near dry lake regions. Tuffeaux, while seeming identical, is actually a yellowish, chalky marine limestone that has blended with sand and other fossil debris.
Basalt
Is the dominant rock found under ocean basins and exposed in places like the lava flows of Hawaii.
Alluvial
These soils are loose, unconsolidated sediments, recently deposited by flowing water; think of stream channel beds, or flood plains. The sediment has not yet been solidified into a mass.
Silt
Is decomposed quartz and feldspar. If they make up granite, too, it is because they are the two most common minerals on earth. Silt feels like flour if dry, or slippery if wet. It’s often dredged up by construction near rivers.
Loess
Silt is easily transported in water or other liquid and is fine enough to be carried long distances by air in the form of dust. Thick deposits of silty material deposited by wind are called loess.
Loam
Is an elusive bastard in the same way marl is. Loam is a mix of sand, silt, and clay; no one element can be in majority. Typical breakdowns are 40% sand, 40% silt, and 20% clay. You thus have different types of loam soils: sandy loam, silty loam, clay loam, sandy clay loam, silty clay loam, and — infuriatingly — just ‘loam’. In the USDA textural classification triangle, the only soil that is not predominantly sand, silt, nor clay is called “loam”. Loam soils generally contain more nutrients than sandy soils. As we all know, wine tastes better when the grapes struggle in poor nutrient soils, so we shouldn’t hear about loam too often in wine terroirs.
Silex
is tricky, because it’s just Latin for ‘hard rock’. It usually refers to flint, a crystalline derivative of quartz, which is nearly pure silica. You may recall flint is used to light fires by striking steel or iron to produce sparks. Its tough, crystal nature made it ideal for shaping arrowheads as well. Flint occurs as masses in sedimentary rocks like chalk and limestone, so it’s inextricably linked to limestone. It’s many different colors, but it’s always smooth and opaque.
Botrytis
Misty mornings, followed by warm sunny afternoons
No. 500 Cow Manure
Cow manure is placed in a cow horn and buried in the ground for the winter. This changes the composition of the manure which is then mixed with water and sprayed at a rate of 60g/ha in 34 liters of water.
No. 501 Horn-Silica
Ground quartz is mixed with rainwater and packed in a cow horn. the horn is buried in the spring and dug up in autumn. The mixture is then sprayed on crops.
No. 502 Yarrow blossoms (Achillea millefolium)
The flower heads are placed in a stag’s bladder. They are applied to compost.
No. 503 Chamomile blossoms (Chamomilla officinalis)
The flower heads are buried in the ground and then reapplied to compost.
No. 504 Stinging nettle (whole plant in full bloom) (Urtica dioca)
Aplied to compost. A tea from Stinging Nettle is sometims sprayed on low vigor vines.
No. 505 Oak bark (Quercus robur)
The oak bark is buried in the skull of a domestic animal (red stag is not uncommon). This is then applied to compost.
No. 506 Dandelion flowers (Taraxacum officinale)
Dandelion flowers are placed in cow mesentery (look that one up!). This is applied to compost.
No. 507 Valerian flowers (Valeriana officinalis)
The juice from the flowers is applied to compost.
No. 508 Horsetail plant (Equisetum arvense):
A tea is prepared from the plant.
American Hybrids
A group of vine hybrids developed in the eastern United States, mainly in the early and mid 19th century and in some cases earlier but also much more recently with cold-hardiness in mind. The term includes hybrids between native american vine species of the genus vitis and a variety of the European vine species vinifera, resulting in such varieties as Black Spanish, norton, concord, niagara, herbemont, delaware, and Othello. The hybrids’ most common parents are the American species V. labrusca and V. aestivalis, along with V. vinifera. These varieties are used for wine production, for unfermented grape juice and jelly, and for table grapes. The fruit is typically highly flavoured, and palates accustomed to the taste of V. vinifera varieties find the foxy character of many American vines strong and objectionable.
American Vine Species- Oxford
Those members of the grapevine genus vitis which originate in North and South America, including Mexico and the Caribbean. When all efforts to grow European vine species vinifera in North America failed through pest, disease, or climatic extreme, wine was made in North America of necessity from these species, detailed below. The most important role for the American species has been to provide the genetic basis for rootstocks on to which V. vinifera vines may be grafted. The species V. berlandieri, V. riparia, and V. rupestris are particularly important as sources of protection against phylloxera, and the great majority of the world’s vineyards now grow on rootstocks derived from them.
Vitis labrusca
Vine species found in the north-eastern United States producing highly aromatic and strongly flavoured berries sometimes described as foxy. The berries fall easily from the cluster when mature and are called ‘slip-skin’, in that a berry squeezed between fingers will eject the flesh as a complete ball (non slip-skin varieties, which are more usual, are squashed when squeezed in this way). Most of the fruit of this species is black, and the leaves are large, thick, and covered on the lower surface with dense white or brown hairs. V. labrusca is a common parent in American hybrids, including concord and catawba.
Vitis aestivalis
Vine species found in the southern and eastern United States which, like Vitis labrusca, is a common parent in American hybrids. The fruit, typically black, is not strongly aromatic and the berries adhere to the cluster when mature. This species shows good resistance to downy mildew and powdery mildew and is therefore a common parent in vine breeding programmes. Norton, which has a reputation for high-quality wine and is enjoying a revival in virginia, is a hybrid derived from V. aestivalis. Early Spanish settlers of north eastern mexico made wine from wild vines of this species as early as 1597.
Vitis riparia
This vine species is widely distributed in eastern North America, from Canada to the Gulf of Mexico. The grapes are not strongly aromatic, with black skin and highly acidic juice. V. riparia is used directly as a rootstock and as a parent of many commercially important rootstocks; the species typically imparts low to moderate vine size to scions and provides protection against phylloxera.
Vitis rupestris
Unusual vine species that grows as a small shrub, found typically on gravelly banks of streams or in watercourses in Texas, Oklahoma, Arkansas, and Missouri. The leaves are small and kidney-shaped and roots tend to grow vertically downwards rather than spread horizontally. A common parent of many commercially important rootstocks because of its phylloxera tolerance or resistance and deep-rooting habit, which can provide protection against drought.
Vitis berlandieri
Vine species found on the limestone soils of Texas and Mexico. The grape is black and its juice is high in sugar and acid without strong flavours. This species is known for being difficult to root from cuttings, but because of its high phylloxera and lime tolerance or resistance, it is a common parent of many commercially important rootstocks.
Soil
Material formed by weathering of underlying bedrock or transported sediments. The main distinction between soil and parent material is a soil’s enrichment with plant and animal remains that undergo decomposition to form soil organic matter. Soil formation is an ongoing process, determined by climate, vegetation, topography, and time, the boundary between a soil and its parent material is usually indistinct. Over very long periods, episodes of erosion and deposition followed by soil formation have led to layered soils. However, where soils have formed on one parent material in situ, distinctive zones called horizons can form in a vertical array, which is called a soil profile. These horizons can be differentiated by their organic matter, colour, thickness, texture, structure, and stoniness. In addition to organic matter, soils are distinguished from rock materials by their structure, which influences the rate of water infiltration, their resistance to soil erosion, and ease of root penetration. The combined effect of soil texture and structure determines a soil’s water-holding capacity, aeration, and drainage. In Australia, when there is a pronounced and relatively abrupt increase in soil clay content between a surface horizon (topsoil) and subsoil horizons, the soil is called duplex. This kind of profile is commonly found in soils referred to as podzolic in many vineyard regions around the world, notably in the US and South Africa. Duplex soils develop impermeable subsoils when the exchangeable sodium content exceeds about 6% of the cation exchange capacity.
Soil Structure
Structure of soils, is an important vineyard characteristic, as governed by bonding of the mineral particles (as described in soil texture) into larger aggregates. The size, shape, and stability of these aggregates help to determine the friability of the surface soil and its ability to accept rainwater and resist erosion. A soil’s structure also determines its porosity for air movement, water drainage, and root penetration, and its capacity to withstand the effects of cultivation and compaction by vineyard machinery.
To a varying degree in different soil types, soil structure depends on the following factors:
- The amount and chemical nature of the clay. To have stable structure, a soil must have a moderate clay content. Montmorillonite clays swell and shrink with wetting and drying, leading to a desirable ‘self-mulching’ of the soil surface, provided the content of exchangeable sodium is not too high. On the other hand, soils with predominantly kaolinitic clays form stable structures at pH less than 6, especially in the presence of iron and aluminium oxides. Illitic clays are intermediate in behaviour.
- The relative contents of exchangeable calcium and sodium. Calcium helps to build up good soil structure, whereas sodium causes clay dispersion and breakdown of the aggregates. In calcareous soils, calcium carbonate can be an effective bonding agent for aggregation.
- Organic matter content. Organic matter in the form of humus bonds to clay particles and iron and aluminium oxides, and so lays the foundation for good structure. Additionally, gums and mucilages secreted by roots and soil micro-organisms play an important part in forming and preserving soil aggregates, and fine roots can form a mesh holding larger aggregates together.
- Soil disturbance by cultivation. All cultivation can be destructive of soil structure, especially in clayey soils when wet. Repeated cultivation exposes organic matter to faster decomposition, which weakens soil structure. Cultivation is sometimes done to improve the ‘tilth’ of the surface soil, but this is a temporary effect and does not improve soil structure in the longer term.
Good soil management aims principally to preserve and strengthen soil structure.
Cepage
French for vine variety. A varietal wine, one that is sold by the name of the principal grape variety from which it is made is known as a vin de cépage within France, a term which has had some pejorative sense in comparison with a geographically named wine which qualifies as appellation contrôlée. High-quality vine varieties such as Syrah (as opposed to such traditional varieties as Carignan and Alicante Bouschet) are described as cépages améliorateurs, or ‘improving varieties’, in the south of France.
Jules Guyot
Respected 19th century French scientist with a particular interest in viticulture and winemaking whose name lives on in the system of cane pruning which he promulgated. His practical treatises on growing vines and making wine were translated into English in the second half of the 19th century and are enthusiastically followed by new world vignerons. Although cane pruning had been used in France for a very long period, it was promoted by Dr Guyot in 1860. The basic principle of Guyot pruning is to leave six- to ten-bud canes and for each a single two-bud spur at the base; shoots from this spur form the cane the following year (see pruning). The Guyot simple form, also known as single Guyot, has one cane and one spur. The length of the cane (in French long bois or aste), or at least the number of buds thereon, may be fixed by appellation laws. Guyot double, or double Guyot, the most common vine-training system in Bordeaux, has two canes and two spurs, and the canes are trained to each side. Sometimes the canes are arched, as in the Jura. Galet lists regional variations of the Guyot.
Head Training
A form of vine training whereby the trunk has a definite head, or knob, consisting of old wood rather than arms of a cordon. Head-trained vines are normally subject to cane pruning, but may, after spur pruning, be described as gobelet. The head may be anywhere between 40 cm/1.25 ft and 1 m/3.3 ft from the ground. The guyot system is a common cane-pruned form of head training.
Cane Pruning
A form of winter vine pruning in which the buds are retained on longer bearers called canes, typically including six to 15 buds. This pruning system usually takes longer to perform by hand than the alternative spur pruning. Cane pruning is typically used for vines which have fewer fruitful buds at the base of canes, which is the case especially in cool-climate wine regions. The tendency in warmer New World wine regions is to use spur pruning, which can be equally productive, requires less labour,
Cation Exchange Capacity
The amount of positively charged ions a soil can hold, is a significant factor in the degree to which soil nutrients are available to the vine. CEC is determined by soil texture, the amount of organic matter in the soil, and the amount and type of clay. Sandy soil has a low CEC. Fine-textured soil such as clay, with a high level of organic matter, tends to have a high CEC.
Cross
The result of breeding a new variety by crossing two vine varieties. If the varieties are of the same species, usually the European vinifera species, then the result may also be known as an intraspecific cross—müller-thurgau would be one example. Crosses of the same species are different from hybrids, sometimes called interspecific crosses, which contain the genes of more than one species of the vitis genus.
Clone
Is a single vine or a population of vines all derived by vegetative propagation from cuttings or buds from a single ‘mother vine’ by deliberate clonal selection. Vine nurseries sell a range of different clones of each vine variety, each with different attributes and characteristics and individually identified by numbers and/or names. In Germany, for example, there is a formal process of clonal evaluation and a systematic numbering system. Normally government agencies are involved in selection, evaluation, and distribution to nurserymen, and often the availability of clones and their acceptance varies regionally. Some clones are so outstanding that they become internationally distributed. Clones of Riesling from geisenheim in Germany are examples of this. In the 1990s, there was considerable interest in Burgundian (sometimes called Dijon) clones; see particularly chardonnay and pinot noir. By the late 1980s, many quality-conscious wine producers were wary of being dependent on a single clone of a particular variety—particularly Pinot Noir—deliberately seeking instead a mixture of clones or, less likely, vines from mass selection, for both viticultural and wine quality reasons.
Cordon Training
A form of vine training in which the trunk terminates in a cordon, and the vine is then typically subjected to spur pruning. The alternative is head training, where the vines are usually subjected to cane pruning. The cordon is normally horizontal and can be unilateral (trained only to one side of the trunk) or bilateral (to both sides)
Chalk
A soft and crumbly, highly porous (35 to 40%) type of pure white limestone and a word often used erroneously as synonymous with it. Chalk-derived soils are valued in viticulture for their excellent drainage, combined with a capacity of the subsoil to store substantial amounts of water. Because vine roots can usually penetrate to chalk bedrock, continuity of moisture supply is assured regardless of short-term fluctuations in rainfall. Pure chalk is of low fertility, resulting in a rather low vine vigour and naturally good canopy microclimate. True chalk is much less common under vineyards than most wine books suggest, chiefly because calcarcous (calcaire in French) has been taken to mean chalky. Apart from some vineyards in southern england, the principal wine region with chalk is champagne. Even here, the better vineyards are mostly on clays, with only the longer roots reaching the underlying chalk. It is also widely believed that the sherry region around Jerez in south west Spain is on chalk, although the bedrock is not even pure limestone. The fact that Jerez, Cognac, and Champagne produce more or less exclusively white wines is one of the bases for the widely held misapprehension that there is a correlation between wine colour and soil colour.
Argilo-Calcaire
French term commonly used to describe soil that is a mixture of limestoneand clay.
Limestone
A rock made of the mineral calcite (calcium carbonate); dolomitic limestone or dolomite is a mixture of calcium-magnesium carbonate. Limestone is calcaire in French.
Common limestones differ from chalk (a soft form of limestone) in being hard and not readily penetrated by plant roots, except through cracks. Unless mineral material is brought in by wind or water, the depth of soil formed on limestone depends on the impurities (clay, silt, and sand) in the limestone because the dissolution of calcite produces only calcium and bicarbonate ions. Some limestone soils, such as the Mediterranean terra rossa, are red-brown in colour; these are moderately alkaline and have a good clay-loam texture and structure. Some limestone soils overlie substantial reservoirs of soil water, of high quality for irrigation. The longer roots of well-established vines may reach these reservoirs, if they are not too deep. Deep ripping to shatter the hard limestone may be carried out before planting, typically to 1 m (3 ft) depth, but any slabs of limestone brought to the surface may need to be removed. Limestone-derived soils are in general valued most highly in cool viticultural regions. The great wines of burgundy come from vines grown on the slopes of the côte d’or escarpment, where Jurassic limestone is the predominant rock but not the only type of limestone found there.The red limestone-derived terra rossa of Coonawarra in south australia similarly produces some of Australia’s best red wines from Cabernet Sauvignon and Shiraz, both vine varieties being close to the cool limit for their reliable ripening. In warm climates, however, such as in the south of France, and the Riverland of South Australia, limestone soils are not regarded as superior, or even necessarily as suitable for viticulture.
Clay
Refers to a particular type of mineral found in some rock types and in soil, and also a description of sediment or soil which is made up of particularly small particles. See soil textureand geology. Soils described as ‘clays’ have a high content of clay minerals, but may also contain fine particles of calcium carbonate (in soils formed on limestone) and quartz (in soils that have been weathering over a long period of time). Clay-sized particles interact with soil organic matter to form soil structure. Different clay minerals predispose to variations in the stability of a soil’s structure. For example, kaolinite clays tend to support stable structures whereas montmorillonite clays, which show marked swelling when wet and shrinkage on drying, may cause structural instability. Mica-type clay minerals can hold significant amounts of potassiumcations within their structures, which can be slowly released on exchange with other cations in the soil water. Clay can be important in vineyard subsoils because of its water-holding capacity, as in parts of pomerol, for example.
Calcium
Is a major nutrient required for vine growth and is rarely lacking in vineyards. It enhances cell wall structure and contributes to grape skin defence against microbial attack. Calcium is immobile in the plant. It is taken up by roots during the period of rapid growth up to veraison, after which point there is little increase in calcium concentration in the plant. calcareous rocks come in many forms, including marl, chalk, limestone, marble, and dolomite. (see geology). The presence of calcium minerals in soils increases friability and drainage, especially where such calcareous soils underlie clay. See soil texture and soil and wine quality. In northerly European wine regions such as Burgundy and Champagne, the drainage encouraged by calcium in the soils accounts for some of their suitability for premium viticulture. Calcium salts have important effects on soil ph and cation exchange capacity. The availability of elements as plant nutrients is broadly correlated with soil ph. Calcium in soils is usually accompanied by a pH of 6–7, at which point many plant nutrients and trace elements are at their most available (see soil acidity, soil alkalinity). The presence of calcium in soils often correlates with the optimum pH for vine growth, which is why liming soils not only tends to improve soil texture but can also increase the availability of nutrients. However, above pH 7, many elements become unavailable, so soils extremely high in calcium carbonate are not ideal for viticulture and cause lime-induced chlorosis.
ELISA
An acronym for enzyme-linked immunosorbent assay, a serological test which can also be used to detect vine pathogens. First used in plant pathology in the mid 1970s, the technique is now used routinely to determine the presence of a wide range of vine pathogens, and test kits are available commercially.
Head Training
a form of vine training whereby the trunk has a definite head, or knob, consisting of old wood rather than arms of a cordon. Head-trained vines are normally subject to cane pruning, but may, after spur pruning, be described as gobelet. The head may be anywhere between 40 cm/1.25 ft and 1 m/3.3 ft from the ground. The guyot system is a common cane-pruned form of head training.
Cordon de Royat
an old form of cordon training used in France for wine grapes since the end of the 19th century (see illustration below). The system was proposed by Lefebvre, director of the French agricultural school of Royat. The classic form is a unilateral cordon on a short trunk (about 30 to 50 cm (12–20 in)), the term unilateral meaning that the cordon is trained only to one side of the trunk. The cordon extends mostly from one vine to another. The vines are normally spur pruned to two-bud spurs. The number of spurs is limited for each variety under appellation laws: in Burgundy, for example, to four spurs each for Pinot Noir and Chardonnay vines, and to eight for Gamay.
Gobelet
a form of vine-training system, used since Roman times, whereby the spurs are arranged on short arms in an approximate circle at the top of a short trunk, making the vine look something like a goblet drinking vessel. The vines are free standing (apart from a small supporting stake when young) and the system is best suited to low-vigour vineyards in drier climates. This is a form of head training and is generally subject to spur pruning. The trunk is short, typically 30 to 50 cm (12–19 in), and the foliage is unsupported by wires. The gobelet is widespread in France, from Beaujolais southwards, although it is now less common than it was because it is generally more economical to train vines on trellis systems rather than have them free standing. The traditional spacing was 1.5 by 1.5 m (5 ft), but the distance has been increased to allow tractor access and the vineyards are typically cultivated in both directions. Sometimes the vines are trained with several trunks. With low-vigour vineyards the foliage can be relatively erect, but shoots may trail on the ground in high-vigour vineyards, and there can be substantial shade. Grape yield and quality may suffer as a result. The system is used widely in many Mediterranean countries and is most suited to low-vigour vineyards. In Italy, the system is called alberelli a vaso, in Spain en vaso, and in Portugal en taça. In many New World countries such as Australia, South Africa, and California, the traditional and low-vigour gobelet-trained vineyards were often called bush vines; they have increasingly been replaced by vines with some form of trellising to accommodate the improved vigour of newer vineyards
California Sprawl
Term commonly used to describe the canopy of a vine trained on a simple trellis system although such systems are not restricted to California. It generally refers to a trellis with a single fruiting wire plus one foliage wire above this, though there are some variations. This results in a sprawling vine without rigorous shoot positioning. This inexpensive form of training can lead to a shaded canopy with poor bud fruitfulness and increased vegetative growth. Such vine forms are more typically seen in vineyards in hotter parts of California’s central valleyand are also common in the inland irrigation regions of Australia. See also canopy management.
Cane Pruning
A form of winter vine pruning in which the buds are retained on longer bearers called canes, typically including six to 15 buds. This pruning system usually takes longer to perform by hand than the alternative spur pruning. Cane pruning is typically used for vines which have fewer fruitful buds at the base of canes, which is the case especially in cool-climate wine regions. The tendency in warmer New World wine regions is to use spur pruning, which can be equally productive, requires less labour, and can be mechanized.
Cane
The stem of a mature grapevine shoot after the bark becomes woody (lignified) and tan-coloured at veraison and starts its overwintering form (see cane ripening and cambium). After leaves have fallen, the canes of a vine display the total vegetative growth it made during the previous season (called the ‘brush’ in the US). The number of canes and their weight and average size are important guides to decisions about balanced pruning and canopy management tactics. The canes are cut at winter pruning to reduce the number of buds and to select their position. The cutting may be to spurs or canes.
Vine Pull Schemes
Have been instituted in various parts of the world at different times, generally in response to a perceived wine surplus. In the late 1980s and early 1990s, smallholders in the south of France and Italy in particular took advantage of substantial financial inducements to abandon viticulture on all or part of their land in an effort to drain the European wine lake. About 300,000 ha/741,000 acres of French vineyard and about 400,000 ha of Italian vineyard were ripped out between the late 1970s and 1991. France’s total vineyard was reduced by a further 80,000 ha and Italy’s by about 150,000 ha between 1991 and 1996, while a further 284,000 ha were ripped out in Spain and 126,000 ha in Portugal. In the following decade, the uptake was greatly reduced, with just 30,000 ha grubbed up, mainly in France. As a result of the EU reforms of 2008, there were further financial incentives to grub up vines in much of Europe but this time farmers were able to apply directly to the EU. As a result, 161,164 ha (398,244 acres) of vines were grubbed up between 2008 and 2011, equivalent to 10% of the European vineyard area. During the same period, 111,364 ha (275,186 acres) were grubbed up without the inducement of a subsidy. However, this has not necessarily resulted in a reduction in wine production. In spain, for example, vineyard restructuring has increased yields despite the ripping out of 150,000 ha of vines. Such schemes are not exclusive to the EU. An even more comprehensive vine pull scheme was enacted within a single country, the Soviet Union, as part of gorbachev’s attempts to curb alcohol consumption. Between 1985 and 1990, the total area under vine in the old USSR fell from more than 1.3 million ha to 880,000 ha/2.2 million acres. Other national vine pull schemes may be directed at particular types of vine in an effort to reduce production of certain wine types—usually in recent history wine of the most basic sort. Such schemes were applied in both argentina and new zealand in the late 1980s, for example.
Wine Lake
Term coined for Europe’s wine surplus. With the introduction of compulsory distillation in 1982, it was rapidly transformed into an alcohol lake.
Auxins
One of a number of groups of natural hormones present in vines which regulate growth. They are produced in vine parts which are actively growing, such as shoot and root tips. Auxins favour cell growth over cell division, but are also involved in inhibiting the growth of lateral shoots. Many chemicals have been synthesized which are chemically related and have a similar biological function. For example, the compounds 2,4-D and 2,4,5-T are auxin-like and form the basis of some herbicides, which are used widely in cereal production. Vines, like tomatoes and cotton, are very sensitive to 2,4-D vapours such as can drift over vineyards when neighbouring farmers use aerial spraying, even from many miles away. Most vine-growing regions have now enacted laws to protect vineyards from the effects of such spraying.
Vine Density
Is a measure of how closely spaced vines are in the vineyard, both within the row and between rows. The choice of vine spacing is one of the most fundamental decisions in planting a vineyard, and between, even within, the world’s wine regions there is enormous variation in spacing. The traditional vineyards of France’s Bordeaux, Burgundy, and Champagne regions have about 10,000 plants per ha (4,050 per acre) (and sometimes more), with vines spaced typically 1 m apart both within and between the rows. In many new world vineyards, on the other hand, a spacing of 2.5 m/8 ft between vines along the row and 3.7 m/12 ft between rows, or 1,080 vines per ha, is quite common. Probably the most widely spaced vineyards of the world are those of the Vinho Verde region in Portugal, La Mancha in Spain, and some parts of Chile, Japan, and Italy (see tendone), with spacings as wide as 4 m by 4 m, or just 625 vines per ha. Some argue that high vine densities lead to improved wine quality. It is true that many of the world’s most famous vineyards, almost invariably in the Old World, have very narrow spacings, and so high densities, but it is difficult to argue that this is a prerequisite for quality production. Narrow spacings are indeed appropriate to vineyards of moderate vigour, which is a feature of the low soil potential of these vineyards (see terroir and soil and wine quality). Some New World vignerons have been encouraged to plant high-density vineyards on fertile vineyard soils in expectation of matching the quality of famous Old World vineyards. The theory is that such dense planting will cause root competition and substantial devigoration, but this has infrequently, if ever, been demonstrated, and the result is often a vineyard of high vigour which is very difficult to manage. The quality of fruit is affected by excessive shade, and this reduces quantity. The belief that ‘tight spacing’ encourages wine quality was widely promulgated in the 1980s and 1990s in California. Despite many commercial experiments, it remains to be demonstrated that wine quality is automatically increased, while the costs of establishing and running such a high-density vineyard certainly are. Research and commercial experience in Europe indicate that close row and vine spacings are suited only to vineyards of low soil fertility, or more correctly of low soil potential. In high-vigour situations, some New World vine-growers have responded by removing one vine in two down the row, and sometimes two in three. This has been found to restore vine balance, and yield and quality have subsequently improved. High-density vineyards are the traditional form of viticulture in many parts of the world, as spacing need only be sufficient to allow the workers unhindered access. Some vineyards are not even planted in rows but were haphazardly arranged, like a field of wheat. Before phylloxera invaded Europe, unhealthy plants could be replaced by layering a cane from an adjacent vine. These considerations, and the fact that vines then were generally less vigorous, encouraged high-density vineyards and densities were as high as 40,000 plants per ha, or just a quarter of a square metre per plant. Once grafting to rootstocks developed as a response to phylloxera, however, then the additional cost of each plant encouraged lower vine densities. The introduction of first animals and then tractors led to the planting of vineyards in rows with a further reduction in vine density. The final factor leading to wider spacing between vines has been the need to provide sufficient space for modern, more vigorous vines. This follows from effective control of vine pests and diseases and weeds using agrochemicals, as well as the use of plants both virus free and subject to clonal selection. Many New World vineyards were planted after the introduction of tractors, necessitating row spacings of about 3 m/10 ft or more. By contrast, most European vine-growers have chosen to persist with narrow rows and to develop either narrow tractors, or over-row tractors, known in France as tracteurs enjambeurs. Vineyard density is a major consideration affecting the vineyard’s yield, quality, cost of establishment and maintenance, and therefore profitability. Planting costs are proportional to the number of plants used; costs for trellis systems and drip irrigation are higher with narrower row spacings. The time taken to plough and spray is also greater when rows are closer together. Under most circumstances, the yield of densely planted vineyards is higher, especially in the first years of the vineyard’s life and with vines planted on low soil potential.
Bush Vines
An alternative term to describe gobelet-trained vines or head training. The comparison with a bush is apt: the vines are trained to a short trunk, normally free standing (without a trellis system), and are pruned to a few spurs commonly arranged in a ring on short arms from the trunk. The term bush vines is used in Australia and South Africa, and there was a fashion for using it on labels in the late 1990s, although many of these old, and typically low-vigour, vineyards have been replaced by vines with a trellis system.
Balance- Vines
Vine balance is a viticultural concept little appreciated by wine consumers, yet one which is essential for producing grapes for premium winemaking. A vine is in balance when the leaf to fruit ratio is in the correct range. The amount of early season shoot growth should also be in balance with the vine’s reserves of carbohydrates. Vine balance concerns vigour and it can be managed by the viticulturist, with balanced pruning and water stress the principal tools. One of the best measures of vine balance is the ratio of fruit yield to pruning weight, now often called the Ravaz index, following its promotion by the French researcher of that name. Balanced wine comes from balanced vines (a fact acknowledged even by such authors as Halliday and Johnson, who were previously critical of high yields in any circumstances). A balanced vine has shoots of moderate vigour with no shoot tip growth during fruit ripening. Leaves are of moderate size and number so excess shade is avoided, with both leaves and fruit well exposed to sunlight. Unbalanced vineyards are either too vigorous—in which case poor ripening results from shading and competition between the ripening grapes and shoot tips for carbohydrates—or not vigorous enough—in which case there is insufficient leaf area for proper ripening. Monitoring shoot tip growth is seen as an important management tool for vine balance.
Balance- Wines
Wine tasters say that a wine has balance, or is well balanced, if its alcoholic strength, acidity, residual sugar, tannins, and fruit, complement each other so that no single one of them is obtrusive on the palate. (Young wines are expected to exhibit more marked tannins than mature ones however.) This extremely important wine characteristic is unrelated to flavour, although see also harmony.
Balanced Pruning
The number of buds to be left on the vine at winter pruning should be judged relative to the vine’s capacity early in the growing season to support the growth of shoots. In turn, a balanced pruned vine will have sufficient shoot growth to ripen the fruit it carries. The amount of late-season growth is related to shoot growth early in the season. The amount of reserve, or stored, carbohydrates in the vine roots, trunk, and arms will determine how many developing shoots can be sustained. Of course, it is impossible to calculate the amount of stored reserves for each vine (which would involve excavation and chemical analysis), so dormant pruning weights are used as an indication. The underlying principle is that the more the amount of shoot growth in summer, the higher will be the pruning weight and also the stored carbohydrate reserves. Pruning weights are simply measured by weighing the cane prunings removed at winter pruning and using this figure to judge the appropriate bud numbers to leave at winter pruning. For example, one formula is to keep around 30 buds for each kg/2 lb of pruning weight. Experienced vine pruners can achieve a similar effect by looking at each vine, judging how it grew last growing season, and adjusting this year’s number of buds accordingly. If too few buds are left on the vine at winter pruning relative to the stored carbohydrates, then shoots in spring will grow quickly and have leaves which are too large and stems which are too thick. The vine will have a high leaf to fruit ratio, which may result in poor fruit set (see coulure). In any event, the leaf to fruit imbalance normally leads to a shaded canopy microclimate and attendant problems of loss of yield and quality. Such a situation is common for vines planted close together on fertile soil. On the other hand, if too many buds are left at pruning relative to stored carbohydrates, then the resulting large number of shoots will develop only slowly in spring. The leaves will be small and the stems spindly. The danger here is that the leaf area will be too low for the weight of grapes, which will ripen slowly and wine quality will suffer. This condition is often described as overcropping.
Bud
Bourgeon in French, is the name given to a small part of the vine shoot which rests between the leaf stalk or petiole and the shoot stem. In the summer it is covered by green scales, which turn brown in winter. The bud contains three miniature, compressed (primordial) shoots. Normally the best developed of these shoots (from the ‘primary’ bud) bursts at budbreak. Grapevine buds are classified as compound and fruitful; their development is complex.
Budbreak
A stage of annual vine development during which small shoots emerge from vine buds in the spring. This process begins the new growing season and signals the end of dormancy, their period of winter sleep. The first sign that budbreak is imminent is bleeding, when the vines begin to drip water from pruning cuts. The buds left at winter pruning begin to swell in the few weeks prior to budbreak, and budbreak itself is marked by the first signs of green in the vineyard, as the first young leaves unfold and push through the bud scales. Budbreak takes place in early spring in cool climates, when the average air temperature is about 10 °C/50 °F. For many northern hemisphere regions, budbreak occurs in March, and for the southern hemisphere in September. Budbreak is more uniform when winters are cold but not subject to winter freeze. In warm to hot regions, budbreak is earlier, and in cooler regions it is delayed. In fact in tropical viticulture the vines never achieve proper dormancy, and budbreak can take place at any time of the year. Not all varieties show budbreak at the same temperature. For example, French studies indicate that for the early table grape Pearl of Csaba budbreak occurs at 5.6 °C, merlot at 9.4 °C, and ugni blanc at 11.0 °C. Late pruning in winter delays budbreak, and this can be used to reduce the risk of winter frost. In temperate regions with warm winters, a few warm days, even in midwinter, can be enough to induce bud swelling, which can lead to budbreak if the warmth persists. One of the very few places around the world to show this problem is the margaret river region in Western Australia. Because of the nearby moderating effects of the Indian Ocean, the midwinter (July) mean temperature is a warm 13 °C. chardonnay vines are particularly prone to this premature budbreak, with only a few buds breaking on the vine in midwinter, and the rest somewhat erratically later in spring. For vines which are properly pruned (see balanced pruning) most of the buds left at winter pruning will burst, and budbreak is near 100%. Budbreak is, however, normally lower for buds in the middle of long canes. (When vines are left unpruned, as in minimal pruning, it is the buds near the ends of canes which burst preferentially, as do higher buds (see apical dominance). The two buds on either side of the cane just below the pruning cut typically burst. This is because of the flow of hormones in the plant and is the reason for pruning to two bud spurs. For the vine-grower, budbreak represents the beginning of about eight months’ work before harvest, during which the vine must be protected from pests, vine diseases, and trained as necessary. The biggest problem for many vineyards at this time of the year is spring frost, to which the young shoot growth is particularly sensitive.
Bunch
Or cluster, the viticultural term for that part of the grapevine comprising bunchstem and berries. Grappe is the French term. Before the berries set, each berry position is occupied by a flower; a bunch develops from the inflorescence of the vine once the berries have set. In the grapevine the inflorescence grows at the node on the side of the stem opposite to a leaf, an unusual position within the plant kingdom. It is closely related to a tendril, both deriving from the same embryonic organ, the anlage. Depending on the time of development, anlagen produce bunches, tendrils, or second crop. Like a tendril, a grape bunch has two arms, called outer and inner. The inner arm develops the bulk of the bunch, while the outer arm may vary in form from a large, well-set ‘wing’ (as in ugni blanc) to a small tendril arm without berries, or it may even abort. Berries on wings sometimes ripen differently from those on the main crop. Bunches vary hugely in size depending on that year’s fruit set and vine variety, from a few grams to many kilograms. They also vary in shape and tightness depending on the lengthening and flexibility of the bunchstem and branches and, of course, on setting and berry size.
Cytokinins
Natural hormones in vines produced in the root tips and affecting the growth of other parts of the plant. Cytokinins favour cell multiplication and affect growth and development of shoots and inflorescences. Fewer cytokinins are produced in dry soils, and also in cold and wet soils, and this appears to be critical for budbreak and early shoot growth.
Gibberellins
Naturally occurring plant hormones which regulate vine growth as for other plants. Isolated in 1941 from a rice fungus, they have been much studied since. In the vine they are formed in growing tissue in the leaves, roots, and berries. Many thousands of hectares of Thompson Seedless (sultana) vines are treated by spraying with gibberellins during flowering and shortly afterwards, and this results in larger berries suitable as table grapes. Other seedless varieties respond similarly to this treatment. Trials at geisenheim and Oppenheim in Germany involving the application of gibberellic acid to seeded grapes during full bloom, causing berry shatter (see fruit set), resulted in a substantial reduction in both botrytis infection and the development of sour rot. The technique is already in commercial use in northern Italy and has proved to be an important way to reduce botrytis problems in Italy and Germany.
Canopy
That part of the vine above the ground, formed by the leaf and shoot system. It includes the trunk, cordon or canes, shoots, leaves, and fruit. It is a term borrowed from forestry, and was first used for grapevines by Professor Nelson shaulis of cornell university.
Noble Rot
Also known as pourriture noble in French, Edelfaüle in German, muffa in Italian, and sometimes simply as botrytis, is the benevolent form of botrytis bunch rot, in which the Botrytis cinerea fungus attacks ripe, undamaged white wine grapes and, given the right weather, can result in extremely sweet grapes which may look disgusting but have undergone such a complex transformation that they are capable of producing probably the world’s finest, and certainly the longest-living, sweet wines. Indeed, the defining factor of a great vintage for sweet white wine in areas specializing in its production is the incidence of noble rot. The malevolent form, which results if the grapes are damaged, unripe, or conditions are unfavourable, is known as grey rot. Ideal conditions for the development of noble rot are a temperate climate in which the humidity associated with early morning mists that favour the development of the fungus is followed by warm, sunny autumn afternoons in which the grapes are dried and the progress of the fungus is restrained. In cloudy conditions in which the humidity is unchecked, the fungus may spread so rapidly that the grape skins split and the grapes succumb to grey rot. If, however, the weather is unremittingly hot and dry, then the fungus will not develop at all and the grapes will simply accumulate sugar rather than undergoing the chemical transformations associated with noble rot, so the result is less complex sweet wine. In favourable conditions, the botrytis fungus Botrytis cinerea spreads unpredictably from grape to grape and bunch to bunch in different parts of the vineyard, penetrating the skins of whole, ripe grapes with filaments which leave minute brown spots on the skin but leave the skin impenetrable by other, harmful micro-organisms. The grapes turn golden, then pink or purple, and then, when they are in a severely dehydrated state, they turn brown, shrivel to a sort of moist raisin, and may seem to be covered with a fine grey powder that looks like ash (to which the word cinerea refers). It can take anywhere between five and 15 days to reach this stage, known in French as pourri rôti, literally ‘roasted rot’. It is almost incredible that such unappetizing-looking grapes can produce such sublime wine, and there have been many instances in which nobly rotten grapes have been discarded, or at least unrecognized, in wine regions unfamiliar with the phenomenon. These visible changes are an outward sign of the extraordinary changes that occur inside the grape. More than half of the grape’s water content is lost due either directly to the action of the fungus or to loss by evaporation as the skins eventually deteriorate. Meanwhile, Botrytis cinerea consumes both the sugar in grapes and, especially, acids, so that the overall effect is to increase the sugar concentration, or must weight, considerably in an ever-decreasing quantity of juice. The fungus typically reduces a grape’s sugar content by a third or more, but reduces the total acidity by approximately 70%; tartaric acid is generally degraded more than the usually less important malic acid. In botrytized wines, most of any balancing acidity is more often due to the concentration of acidity in the shrivelled but non-botrytized berries that are harvested, and then fermented, at the same time. While it metabolizes these sugars and acids, the fungus forms a wide range of chemical compounds in the grape juice, including glycerol (quite apart from that formed by alcoholic fermentation), acetic acid, gluconic acid, various enzymes especially laccase and pectinase, as well as the yeast-inhibiting glycoprotein dubbed ‘botryticine’, which limits yeast growth and increases the production of acetic acid and glycerol during fermentation. The phenolics in the grape skins are also broken down by the fungus so that the tannin content of the juice is significantly reduced. In sum, botrytized grape juice is very different from regular grape juice, and not just because of its intense levels of sugar. Masuda et al. identified sotolon as a contributor to the aroma of botrytized wines. It is unusual for all grapes on a vine, or even on a single bunch, to be affected in exactly the same way, to exactly the same effect, and at exactly the same speed, which is why the harvest of a botrytis-affected vineyard can necessitate several passages, or tries, during which individual bunches, or parts of them, are picked at optimum infection level, and grapes affected by grey rot may have to be eliminated. Weather conditions other than alternating early mists and warm afternoons can result in a satisfactory noble rot infection. In cold, wet weather, noble rot may form at a reasonable rate on fully ripe grapes, and grey rot be kept at bay. Wind can help to dehydrate the grapes and concentrate the sugars.
Botrytis
Without the capital B it botanically deserves, is commonly used as an abbreviation for botrytis bunch rot, for the fungus that causes it Botrytis cinerea Pers, for its benevolent form noble rot, and occasionally for its malevolent form grey rot. Grapes affected by noble rot and the wines produced from them are often called botrytized, or botrytis affected.
Botrytized
Are those made from white grapes affected by the benevolent form of botrytis bunch rot, known in English as noble rot. Distinctively scented in youth, and with considerably more extract than most wines, they are the most complex and longest lived of all the sweet, white table wines. The noble rot smell is often described as honeyed, but it can also have an (attractive) overtone of boiled cabbage.
Botryized- History
There is no firm evidence that botrytized wines were recognized in antiquity, although Olney points out that a particularly fine Ancient Greek wine produced on Chios in the 5th century bc is described as saprian by athenaeus, and that the literal translation of this may be ‘rotten, putrid’. Noble rot is much more likely to occur in more humid climates than in the mediterranean climate of the Aegean Islands, however, and the extremely unpleasant appearance of grapes infected by noble rot, and the difficulty with which they ferment, must have deterred many early winemakers. Three important centres of botrytized wine production have their own accounts of the discovery that this particular sort of mouldy grape could be transformed into exceptional wine. That of the tokaj region of north east Hungary is the oldest, dating from at least 1650 when the priest-cum-winemaker on a particular estate there delayed the harvest because of the threat of attack by the Turks. This allowed the development of noble rot and the grapes were duly vinified separately, as one would expect, and the resulting wine much admired. For diplomatic purposes it was introduced to the French court in the early 18th century, long before French vine-growers had recognized the existence of the noble fungus. In Germany, the principle of picking selected bunches of grapes (auslese) was understood in the 18th century, but that of the widespread picking of grapes affected by noble rot dates, in the Rheingau region which became most famous for botrytized wines, from about 1820. In spite of popular beliefs to the contrary, precisely when and where vine-growers first realized the value of noble rot is not certain, although the discovery in Germany is thought to have been in the particularly suitable climate of the Rheingau. schloss johannisberg has certainly promulgated its own claim that in 1775 the traditional harvest messenger, as usual licensed to deliver permission to pick from the owner, the distant prince-abbot of Fulda, was delayed, thereby supposedly allowing a noble rot infection to proceed, and resulting in Germany’s first botrytized spatlesse. The sweet wines of Bordeaux and the Loire were much treasured in the Middle Ages, particularly by the dutch, but without any specific mention of a special fungus, or acknowledgement of any special attribute. The principal French legend concerning the ‘discovery’ of noble rot—and legend it is widely believed to be—dates from as recently as 1847, at Ch d’yquem (although the quality, style, and youthfulness of earlier vintages of Yquem, such as the 1811, suggest that noble rot must have played an important part in wine production there before that date). The risks and costs involved in making naturally botrytized wine make it necessarily expensive. It has therefore been an economical proposition only when sweet wines are highly valued. Germany’s botrytized wines have always been regarded as precious rarities for which a ready market can be found within Germany. France’s output of botrytized wines is potentially much greater, but when sweet wines were out of fashion in the 1960s and 1970s, enthusiasm for producing them inevitably waned, only to be rekindled in the 1980s.
Botryized- Geography and Climate
Many conditions have to be met before botrytized wines can be produced. Not only is a mesoclimate which favours misty mornings and warm afternoons in autumn needed, but producers must have the knowledge and the will to sacrifice quantity for nothing more certain than possible quality. Botrytized wines are very much a product of psyche as well as nature. The district with the potential to produce the greatest quantity of top-quality botrytized wine is sauternes (although it all depends, as everywhere, on the precise weather of the year). The confluence of the Rivers Ciron and garonne provide an ideal mesoclimate for the satisfactory development of noble rot. Nearby sweet white wine districts cérons, loupiac, cadillac, and ste-croix-du-mont may also produce small quantities of botrytized wines, although the price fetched by these appellations rarely justifies the additional production costs. Botrytized wine is also made by the most meticulous producers in monbazillac and saussignac. With viticultural commitment and skilful vinification, these districts can make botrytized wines to rival all but the very best Sauternes made similarly from Sémillon, Sauvignon, and particularly Muscadelle grapes. One or two fine examples of this style have also emerged from Gallic. On the river Loire, appellations such as Coteaux de l’aubance, Coteaux du layon, quarts de chaume, bonnezeaux, montlouis, and vouvray can produce botrytized wines in good years, and they are given even greater ageing potential for being made from the acidic Chenin Blanc grape. Botrytized wines may also be made from such varied grapes as Mâconnais Chardonnays and Alsace Rieslings in exceptional years. Germany is the other famous source of botrytized wines, usually labelled beerenauslese or trockenbeerenauslese, although the quantities made vary enormously according to vintage. Riesling is the classic grape, although some of the german crosses can be persuaded to rot nobly in an exceptionally suitable year. Noble rot infections are much more reliable in the burgenland district of Austria, where, thanks to the influence of the neusiedlersee, considerable quantities of botrytized Beerenauslesen and Trockenbeerenauslesen are made most years. Over the border in Hungary, Tokaj is still closely associated with botrytized winemaking, as various parts of romania, notably cotnari, once were. Botrytized winemaking is an embryonic art in Italy, Spain, and most of Portugal, where producers and consumers tend to favour either dried-grape wines or fortified wines. In the New World, botrytized wines are made with increasing frequency. Nederburg Edelkeur was a South African prototype which enjoyed international acclaim in the 1970s. Griffith in new south wales’s Riverina was producing Australian botrytized Pedro Ximénez as early as the late 1950s, and is now a centre for the production of relatively early maturing botrytized whites, particularly Semillon. In Australia, New Zealand, South Africa, and in California particularly, a host of botrytized Rieslings has emerged. California has also seen attempts to simulate noble rot, by growing spores of the botrytis fungus in a laboratory and spraying them on picked, healthy, ripe grapes before subjecting them to alternately humid and warm conditions for a couple of weeks. The first of these wines was made in the late 1950s by Myron Nightingale in the Livermore Valley. The result was called Premiere Semillon and has been followed by a series of similar wines made at Beringer in the Napa Valley. As awareness of noble rot and botrytized wines grows, the number of winemakers anxious to experiment also increases, even if the market is not always rapturous, and they are usually at the mercy of the weather. Even england has succeeded in producing botrytized wine.
Botryized- Vine Varieties
Any white grape variety may be infected benevolently by the botrytis fungus; red varieties simply lose their colour. and usually develop off-odours. Certain varieties seem particularly sensitive to the fungus and well adapted to the production of botrytized wines, however: Sémillon, Sauvignon Blanc, Chenin Blanc, Riesling, Gewürztraminer, and Furmint are traditional.
Botryized- Viticulture
The chief viticultural aspect of making botrytized wines is the number of passages or tries through the vineyard which may have to be made in order to pick grapes only at the optimum point of botrytis infection, because noble rot is so crucial to quality. See sauternes for a description of the likely routine there. In a year as difficult as 1974 at Ch d’yquem (admittedly the most conscientious Sauternes estate), 11 tries were made over a ten-week period. In 1990, on the other hand, noble rot spread rapidly and uniformly and the grapes were picked by early October. In some vintages the spread and quality of botrytis may be so patchy that some estates, for example Yquem, Rieussec, and Suduiraut in 2012, elect not make a grand vin. Hand picking of these varied but usually disgusting-looking grapes is essential, and the cost of labour is one important element in the price of botrytized wines. In wet vintages, some producers use modern freeze-concentration techniques, called cryoextraction in French.
Botryized- Winemaking
If picking botrytized grapes is painstaking, obtaining their juice and persuading it to ferment is at least as difficult because of its composition (see noble rot). pressing is a physically difficult operation, and, contrary to the usual practice, later pressings yield juice superior to the first pressing because it is richer in sugar and the chemical compounds produced by the botrytis fungus. The most dehydrated grapes in the press may not in any case yield juice until they have been pressed twice or three times. A variety of winemaking methods are used, including the classic method described in sauternes. Fermentation is necessarily extremely slow. The juice seems almost designed to inhibit yeasts, being so high in sugar and antibiotics such as botryticine. Botrytized musts tend to lack nutrients such as thiamine and ammonia, which is another reason for stuck fermentations. Fermentation may be allowed to stop itself, or sulfur dioxide addition may be used. Care must be taken that these wines, which often have a residual sugar level equivalent to about 6% alcoholic strength, do not suffer a second fermentation, and bottling, whether after two winters in new barriques as in the top Sauternes properties, or in the following spring as in the Loire and many German cellars, has to be undertaken with care. Higher levels of sulfur dioxide are needed during vinification and at bottling because the enzyme laccase produced by botrytis increases the risk of oxidation and is tolerant of high levels of sulfur dioxide. In addition, the chemical composition of botrytized wines means they have significant power to bind sulfur dioxide. This is why eu regulations permit a higher level of total sulfur dioxide for these wines than for all others. The development of Botrytis cinerea also results in the production of two polysaccharides. One has antifungal properties and inhibits fermentation. The other, a β-glucan, can make filtration much more difficult, especially if crushing, pumping, and pressing are carried out harshly. Some wines, notably those made from aromatic varieties such as Muscat, are marked by a loss of varietal aroma. This is mainly because botrytis metabolizes the monoterpenes such as linalool and geraniol that are responsible for the distinctive aromas of such varieties. Botrytized wines are capable of extremely long bottle ageing, for many decades in some cases.
Powdery Mildew
Also called oidium, oïdium in French, the first of the vine fungal diseases to be scientifically described, in 1834 in the United States. It is native to North America, where it causes minor damage on native grapes. The fungus was given the name Oidium tuckerii after the gardener, a Mr Tucker, who first noted it in Europe, in Margate, England, in 1845 (Barron says 1831 or 1832). Today the fungus is more widely known as Uncinula necator. The disease was first noted in France in 1847, where it soon spread and caused widespread havoc to vineyards and wine quality. Today the disease is spread worldwide. There is a difference in susceptibility between different vine species, with many native american vines being very resistant. Varieties of the European vine Vitis vinifera are generally very susceptible, although some variation is noted. For example, Aramon, Pinot Noir, Malbec, Merlot, and Riesling are noticeably more tolerant than Carignan, Colombard, Chardonnay, and Cabernet Sauvignon. All green parts of the vine are attacked and the infection is very visible. A fine, translucent, cobweb-like growth spreads around the spot where the fungus first penetrates. After one to two weeks, grey-white ash-like spores are produced on short, upright stalks. The infection looks powdery, leading to the common name. Spores are spread by wind and, with favourable conditions, new infections rapidly occur. The fungus survives over winter inside buds or on the surface of the vine. If bunches are infected before flowering, then fruit set and yield may be considerably reduced and berry ripening delayed. Yield can be further reduced if berries are infected before they reach full size. Surface cells are killed so that the berries never grow to full size. Fruit of coloured varieties also fails to colour properly. Fruit infected with powdery mildew is universally avoided in winemaking, and until recently there has been surprisingly little research into the effects on wine quality. Studies in New York state and Australia agree on the following points: wine made from infected bunches loses its fruity aromas, to be replaced by mouldy, wet fur, and earthy characters; wines are described as ‘oily’ and ‘viscous’. The greater the infection, the more obvious the effects. The disease develops and spreads most rapidly in warm weather, 20 to 27 °C (68–80 °F). Unlike all other fungal diseases of vines, this one is little affected by humidity, making climate conditions which favour it different from those which favour many others. Powdery mildew is favoured by dense, shaded canopies. In fact, bright sunlight, especially the ultraviolet part of the spectrum, inhibits the germination of spores. Fortunately the control of this disease was discovered soon after it appeared in Europe. Mr Tucker noted the similarity between this vine disease and that affecting peach trees, which could be controlled by a mixture of sulfur, lime, and water. Dusting with sulfur was accepted after the disastrous French vintage of 1854, the smallest since 1788. This same technique is still used today. In dry climates, sulfur dust is used; wettable powders are used in higher rainfall regions; and organic fungicides have been developed more recently. Cultural practices such as maintaining a non-shaded canopy (see canopy microclimate) help prevent development of the disease. Recent developments in vine breeding have produced varieties with natural resistance and acceptable wine quality. These disease-resistant varieties use the natural tolerance of native American species somewhere in their pedigree.
Downy Mildew
One of the most economically significant fungal diseases affecting vines, often called peronospora in parts of Europe. It is a particular problem in regions with warm, humid springs and summers such as many wine regions in northern Europe. The disease is caused by the organism Plasmopara viticola. This fungus is indigenous to eastern North America, and so some species of native american vines such as Vitis cordifolia, Vitis rupestris, and Vitis rotundifolia are relatively resistant. Commercially important varieties of vinifera, however, are highly susceptible. The fungus caused havoc in the vineyards of Europe when it was accidentally introduced before 1878, probably on American vines imported as grafting stock to combat phylloxera. By 1882, the disease had spread to all of France. The famous bordeaux mixture was first used as a preventive spray to control this disease. The disease is now widespread around the world, but a few areas with low spring and summer rainfall are essentially free of it. These include Afghanistan, northern Chile, Egypt, and Western Australia. It has occurred spasmodically in California and southern Chile. Downy mildew attacks all green parts of the vine and young leaves are particularly susceptible. When severely affected, leaves will drop off. The loss of leaves reduces photosynthesis and thus causes delays in fruit ripening and, typically, levels of fruit sugars, vine reserves of carbohydrates, and anthocyanins are depressed. budbreak and early shoot growth can be delayed the following spring. Severe infections result in pale, puny reds and weak whites. The symptoms of the disease are described quite aptly by the name. Leaves show patches of dense, white cottony growth on the undersurface. The earliest stage of the fungus is the so-called ‘oil spot’, easily seen on the upper leaf surface when it is held up against the light. petioles, tendrils, young inflorescences, and developing berries are also affected. The fungus spends the winter in fallen leaves and can sometimes survive in the buds. Spores germinate in the spring when temperatures reach 11 °C/52 °F and they are spread to the vine by rainsplash from the soil. Spores are further spread and germinated with high humidity (95 to 100% relative humidity), warm temperatures (18 to 22 °C), and moisture. The most severe epidemics of the disease occur with frequent rainstorms and warm weather. The low yields of the French vintages of 1886, 1910, 1915, 1930, 1932, 1948, 1957, and 1969, all of them produced after wet growing seasons, were probably due to downy mildew. There are two principal protection approaches. The first and most common is to use protective sprays which are often based on copper. However, the protection lasts for only ten days or so, especially when the shoots are growing rapidly in early spring. Curative fungicides which act against established infections became available in the early 1990s, but these are more expensive. A modern approach is to install a vineyard weather station which can predict outbreaks by measuring the weather. An alternative but less popular approach to the control of this disease is to plant disease-resistant varieties. European vine breeders, especially at geisenheim and geilweilerhof in Germany, have been particularly successful in developing varieties which require no, or less, spraying against downy mildew, with native American vines contributing the resistant genes. Increased environmental awareness may encourage their use, but there is substantial consumer resistance to new varieties.
Bitter Rot
A fungal disease of ripe grapes that is active in warm, humid conditions. It is found only on damaged and almost senescent tissues, but the bitter fruit flavour can be detected in the finished wine. The cause is the fungus Greeneria uvicola and the disease is widespread in the eastern United States, Asia, Australia, and South Africa but not in France or Germany. The disease is easily controlled by most fungicides.
Black Rot
Fungal disease which is one of the most economically important diseases of vines in the north-eastern United States, Canada, and parts of Europe and South America. The disease is native to North America and was probably introduced to other countries by contaminated cuttings. It was introduced to France, for example, on phylloxera-tolerant rootstocks as early as 1885. The disease is caused by the fungus Guignardia bidwelli, which attacks young shoots, leaves, stems, and berries. The disease spreads only in mild, wet weather. Crop losses can be high, up to 80%. Control of the disease is based on fungicides sprayed from spring up to fruit ripening and removing from the vineyard infected mummified berries. The disease is causing renewed concern because of its recent spread in Europe. As might be expected from the origin of the disease, some native American species are tolerant.
Aphids
Small insects of the Aphidiodae family that feed by sucking the juices from plants. Several species of aphids attack grapes, but apart from phylloxera, they seldom cause serious damage in vineyards.
Ladybug Taint
Also known as lady beetle or ladybird taint, is an off-flavour found in both grape juice and wine that contributes undesirable peanut- and/or green-like aromas and flavours, and possibly excessive bitterness. Two lady beetle species that migrate to vineyards during autumn—the seven-spot ladybird/ladybug (Coccinella septempunctata) from Europe, and particularly the multicoloured Asian lady beetle (or harlequin ladybird, Harmonia axyridis)—are known to cause the taint in the US and Canada. Both were originally introduced to North America to control aphids. It is unlikely that the beetles directly harm the grapes. Instead, they cause contamination after they are inadvertently harvested with the fruit and are incorporated in the must. The compounds responsible are alkyl-methoxypyazines—components of the insects’ haemolymph—and are difficult to remove from affected juice and wine, although juice settling and must-heating prior to fermentation can help. While not always openly acknowledged, ladybug taint is a problem in some wines and vintages across many of the world’s wine regions, including the US, France, Germany, and Canada. The first major incidence in northern North America was in 2001, while the 2004 and 2011 vintages in Burgundy were probably the first two to be widely discussed in this context. In Europe, however, the culprit seems to be the common seven-spot ladybird.
Bacteria
Very small micro-organisms which have serious implications in both viticulture and winemaking. Although not common pathogens of the grapevine, bacterial diseases are potentially destructive and therefore very important. In winemaking just two groups of bacteria are important, acetobacter and lactic acid bacteria. Since grape juice and wine are both high in acidity, the great majority of bacteria, with the exception of these two groups, are incapable of living in them and, if introduced, do not survive. (Drinks such as cider, perry, orange juice, and beer are all much less acid than wine, are thereby subject to many forms of bacterial spoilage to which wine is immune, and therefore lack wine’s ageing potential.) No known human pathogenic bacteria can survive in wine, however, which is one of the reasons why it has been such a safe drink (safer than water at some times and in some places) through the ages. Acetobacter (which do not harm humans) can turn wine, or any other dilute solution containing ethanol, into vinegar. Acetobacter require oxygen for growth and survival and they die in the absence of oxygen (which is why care is taken to exclude oxygen from certain stages of winemaking and all stages of wine preservation). Lactic acid bacteria produce lactic acid and grow best in environments where there is a very small amount of oxygen. They are important as the agents of malolactic conversion in wines, by which excess malic acid is decomposed.
Fungal Diseases
Very large group of vine diseases which are caused by small, mostly microscopic, and filament-shaped organisms. Since fungi lack chlorophyll they need to live on other organisms to obtain nourishment. Fungal diseases have been of major significance in affecting grape production over centuries, with important consequences for both quantity and quality. Today they receive little public attention since they can successfully be controlled by a wide range of agricultural chemicals. In fact the famous fungicide bordeaux mixture was used commercially to control downy mildew in 1885 and for 50 years was the most important control of other fungal and bacterial plant diseases. Fungal disease epidemics are commonly related to weather conditions; examples are downy mildew and botrytis bunch rot, both of which are favoured by warm, wet or humid weather, while powdery mildew is favoured by overcast weather. Many of the economically important fungal diseases originated in America and therefore common varieties of the European vinifera species have no resistance. Thus, when powdery mildew was introduced in 1847, and then downy mildew in 1878, French V. vinifera vineyards were devastated. Fungal diseases can attack shoots and leaves but also developing bunches and ripe fruit. Some fungi such as Armillaria and Verticillium attack roots. Of more recent concern are a group of fungi which cause trunk diseases. They spread in vineyards and are also common contaminants of young vines propagated in grapevine nurseries. Botrytis is the fungus with which wine consumers are probably most familiar. In its benevolent form (see noble rot), it contributes to a high proportion of the most famous sweet wines. The more common malevolent form (see grey rot) causes substantial yield and quality losses, on the other hand. Common fungal diseases are anthracnose, armillaria root rot, black rot, botrytis bunch rot, bunch rots, collar rot, dead arm, downy mildew, esca, eutypa dieback, powdery mildew, texas root rot, verticillium wilt, white rot. Other groups of vine diseases include bacterial diseases, phytoplasma diseases, and virus diseases.
Nematodes
Microscopic roundworms generally found in soil which can seriously harm vines and other plants. Some feed on bacteria or fungi and are part of the normal vineyard ecosystem. Others, however, feed on grapevine roots and thus reduce both the size and efficiency of the root system. Although the vines do not necessarily die, they suffer water stress and deficiencies in vine nutrition and grow weakly. Some species of nematodes are important because they transmit virus diseases. The viruses spread by nematodes are called nepoviruses. They can be spread throughout the vineyard from just one infected plant by nematode feeding. Often they show up as a few yellow vines in the vineyard. The fact that nematodes damage vines was first established in about 1930, in California. Because of characteristic and visually striking root damage, the root knot nematode, Meloidogyne species, was considered most important. However, in 1958 it was discovered that fanleaf degeneration was spread by nematodes of the species Xiphenema index, the so-called dagger nematode. This milestone discovery in plant pathology was made by Hewitt and colleagues of the University of California at davis. It had been established in France as long ago as 1883 that fanleaf degeneration spread through the soil, and some French authorities believed until the 1950s that the phylloxera louse was responsible for the spread. Root knot nematodes occur mainly in sandy soil. Their presence is visible to the naked eye since the knots (swollen tissue or galls) on the roots formed in response to their feeding resemble a string of beads. One female can lay up to 1,000 eggs, and with up to ten generations a year in warm climates they can spread rapidly. The root lesion nematode Pratylenchus also damages vines by feeding on their roots. Virus particles can survive for many years in root fragments after an infected vineyard is removed. Replanting a new, ‘virus-free’ vineyard can lead to disappointment, as reinfection with nematode feeding can follow. At one time vineyards in which nematodes were previously present were subjected to fumigation with injected chemicals before planting, but the nematicide DBCP, which was considered capable of controlling all nematodes, is now banned. Methyl bromide was highly effective but was banned in 2005 because of environmental considerations. In California, where methyl bromide was widely used for vineyard replanting, integrated pest management is suggested as an important alternative. Nematode diseases are often spread on infected planting material or by the movement of infected soil on cultivation implements or by irrigation water. Infected nursery plants can be freed of nematodes by hot-water treatment. Biological control using rootstocks is possible and generally preferred. Some vitis species (V. solonis, V. champini, and V. doaniana) show resistance to nematodes. Among the most nematode-resistant rootstocks are Couderc 1613, Ramsey, Schwarzmann, Harmony, and Dog Ridge.
Chlorosis
Vine disorder in which parts or all of the foliage turn yellow due to lack of chlorophyll. The most common and extreme chlorosis is that which is visible in spring and early summer and is caused by iron deficiency, which is common on soils high in limestone. Lime-induced chlorosis became a problem in parts of France as a consequence of phylloxera invasion at the end of the 19th century, since american vine species sourced initially in the eastern US and used as phylloxera-resistant rootstocks were more prone to iron deficiency than were the original vinifera root systems. This problem, known in French as chlorose calcaire, has been largely overcome now by the selection of lime-tolerant rootstocks suitable for calcareous soils, such as 41 B or the newer Fercal. In Burgundy and Champagne, where soils tend to be high in limestone, it has been difficult to find rootstocks with sufficient lime tolerance for healthy vine growth. This sensitivity of early post-phylloxera rootstocks to lime-induced chlorosis may provide part of the explanation for an apparent drop in quality in post-phylloxera wines, according to some historical authorities. Chlorosis is a common symptom of deficiencies of other nutrients such as nitrogen, sulfur, and magnesium. It can also be caused by some vine diseases. The effect may be general, as for fanleaf degeneration virus, or more localized, as in, for example, the so-called oil spot on leaves due to downy mildew infection.
Agrochemicals
The materials used in agriculture to control pests and diseases. They include fungicides, insecticides, herbicides, bird repellents, plant growth regulators, rodenticides, and soil fumigants. A broader definition might also include fertilisers. Viticulture requires fewer agrochemicals than many other field crops, partly because such a high proportion of vines are grown in warm, dry summer environments in which fungal diseases are relatively rare, and also because vines require fewer fertilizers than most other crops (see vine nutrition). Vines grown in humid, warm summers may require as many as ten or more sprayings, however. Vine-growers, like other farmers, are in general becoming less reliant on agrochemicals as a result of increased environmental concerns (see sustainability), and as alternative approaches become available. Some diseases, notably botrytis bunch rot, develop tolerance to the repeated use of some chemicals, and so their continued use is now subject to resistance-management strategies. Alternative approaches may take the form of integrated pest management (IPM) programmes, which aim to apply chemicals more rationally, or the adoption of some form of sustainable, organic or biodynamic viticulture, which aim to minimize the use of agrochemicals. The use of agrochemicals in viticulture is strictly regulated by governments. The process of registering a new agrochemical with a government is lengthy, exacting, and costly. Such registrations specify, for example, withholding periods that must elapse between the last application and when the crop is harvested to allow residues of the agrochemical to diminish to suitably low concentrations. To save money, some manufacturers do not register chemicals with all governments, with the result that small and emerging wine industries, like that of the UK, are disadvantaged by having access to only a limited range of products. In the case of wine, the effect the agrochemical may have on fermentation is also assessed. For example, the fungicide folpet, which is used in some countries to protect vines against downy mildew, may delay, or even prevent, fermentation by some wine yeasts if present at certain concentrations. Because an official maximum residue limit (MRL) may not exist for an agrochemical in all countries, world trade may be adversely affected. For example, the fungicide procymidone, which has been used in parts of Europe, is not registered in the US for use on any crop. When the American authorities detected residues of procymidone in some European wines in early 1990, they banned the importation of any European wine containing residues of procymidone until a permissible residue level was established. This had a serious effect on many sectors of the European wine trade. The Codex Alimentarius (‘food code’ in Latin) was established by the Food and Agricultural Organization (FAO) and the World Health Organization (WHO) to upgrade and simplify international food regulations and to avoid such incidents. Codex MRLs have been set for some agrochemicals in a range of crops, and several countries accept Codex MRLs in the absence of their own. The US does not recognize Codex MRLs, however. Although an agrochemical may be present in formulations bearing different proprietary names, it usually has a single common name that is recommended by standards organizations. For example, the fungicide Rovral® (from manufacturers Rhône Poulenc) contains the agrochemical iprodione that is also the active constituent of several other fungicides.
Alternative Viticulture
Forms of viticultural practice such as organic and biodynamic, which usually aim to minimize environmental degradation. See also sustainable viticulture.
Biodynamic Viticulture
Is, an enhanced or extreme form of organic viticulture. This controversial practice has produced some impressive results but without the reassurance of conclusive scientific explanation. Biodynamics is the oldest ‘green’ farming movement, pre-dating organics by 20 years. It is based on theories described in 1924 by the Austrian philosopher Rudolf Steiner (1861–1925) for agriculture in general. All biodynamic vineyards practise organic viticulture, but biodynamics differs from organics in three ways. The vineyard should become a self-sustaining individual or ‘farm organism’ (see sustainable viticulture and ecosystem): it should be treated regularly with nine herb- and mineral-based biodynamic ‘preparations’; and key tasks such as planting, pruning, ploughing, picking, and bottling should be timed to harness beneficial ‘formative forces’ exerted by earthly and celestial—planetary, solar, stellar, and especially lunar—rhythms. France’s first biodynamic wine-grower, François Bouchet (1932–2005), began using the technique on his 6 ha/15 acre Domaine de Château Gaillard in Touraine in 1962. But France’s biodynamic wine movement remained almost non-existent until the late 1980s, when Bouchet began helping leading names such as Domaine Leflaive of puligny-montrachet, Domaine leroy in Vosne-Romanée, chapoutier in Hermitage, Huet in Vouvray, and Kreydenweiss in Alsace to convert to biodynamics. These producers shared a belief that only a less technologically driven form of viticulture would allow wine quality to keep improving, and were emboldened by former inra soil microbiologist Claude Bourguignon’s 1988 declaration that Burgundy’s vineyards contained ‘less life than Sahara desert sand’. Bourguignon made no claim to understanding how biodynamics works; but his research showed that levels of microbial life in vineyard topsoils (see soil biota) were significantly greater on organic and biodynamic plots than on those of conventionally farmed ones. In addition, Bourguignon found significant increases of microbial life on biodynamic vine roots at depths of several metres compared with conventionally and even organically farmed vines, and that the roots were thickest, longest and most able to penetrate the soil, and to assimilate trace elements (see vine nutrition, micronutrients, and mycorrhiza), when grown biodynamically. The particularity of biodynamics is the use of animal sense organs such as cow horns as sheaths when making six of the nine biodynamic preparations. It is believed that animal organs enable the medicinal properties of the substances encased within—cow manure, ground quartz, oak bark, and the flowers of yarrow, chamomile, and dandelion—to become fully effective throughout the farm, keeping it within what Steiner called ‘the realm of the living’. The animal organ sheaths disintegrate naturally or are discarded before the preparation material within is applied. Nevertheless, it is this aspect that convinces non-believers that biodynamics is an unscientific and disturbingly irrational cult. The two main biodynamic field sprays are horn manure and horn silica. Only a handful of the former or a few grams of the latter are required per hectare. They are prepared by burying the cow manure or the ground quartz (silica) in a cow horn for six months over winter or summer respectively. Horn manure is sprayed on the soil in the afternoon, in autumn and early spring, to stimulate microbial life in the soil, helping maintain soil structure and levels of organic matter, and encouraging deeper vine roots. Horn silica is sprayed over the vines, at sunrise, either side of flowering to regulate plant metabolism and promote stronger, more upright vine growth, to lignify the wood, and to improve the nutritional and keeping qualities of the wine. One further field spray, the silica-rich common horsetail (Equisetum arvense), is sprayed as a fresh tea or fermented liquid manure to encourage fungal spores to remain in the soil rather than affecting the vine. It is a fundamental tenet that all three biodynamic spray preparations are ‘dynamized’ before application. This involves rhythmically stirring the material in water, first one way and then the other, to create a vortex. When the direction of stirring is changed the water is thought to undergo chaos, allowing beneficial ‘formative forces’ within the preparation to be transferred to the water and thence to the vineyard when it is sprayed. Organic fertilizer in the form of compost is used to nourish the soil but biodynamic compost differs from other composts in that the remaining six biodynamic preparations made from yarrow, chamomile, stinging nettle, oak bark, dandelion, and valerian must be inserted into the compost pile, which should be manure-based. The compost preparations are said to infuse the manure with vitalizing living forces whose role is more important to vine growth and form than the actual composted manure. Where specific ingredients are not available, substitutes may be used. For example, Casuarina stricta is often substituted for common horsetail in Australia. Late-20th-century mechanization saw the almost complete disappearance of livestock from vineyards. Biodynamic growers are at the forefront of reversing this trend by acquiring livestock for manure (cows), traction (horses, mules), weed control (sheep), or pest control (chickens to eat cutworms). In this way, vine monocultures begin changing towards the biodynamic ideal of self-sustaining farm organisms, creating a natural equilibrium in which pests and diseases become potentially far less potent. Biodynamic growers see plants as comprising four ‘organs’: root, leaf/shoot, flower, and fruit, and these are respectively linked to the four elements of earth, water, air, and fire (solar heat). Each plant component is said to be favoured during particular points of the moon’s sidereal cycle when the moon passes in front of one of the 12 constellations of the astronomical (rather than astrological) zodiac. Thus, for example, spraying horn manure on the soil for root growth is said to be most effective if the moon is in front of an earth/root constellation such as Bull, Virgin, or Goat. These windows occur every nine days or so but for two or three days only, so only the smallest vineyards, or those with abundant labour, can time all their agricultural work according to the biodynamic calendar. Biodynamicists claim that on conventional vineyards where neither biodynamic compost nor the field spray preparations are used, the effect of these earthly and celestial rhythms will not be felt as the soil and the vines will not have been sensitized to them. Cellar work is also said to benefit from the biodynamic calendar, with, it is claimed, bottling best under Lion if the wine is designed to age (the heat/fruit ‘force’ will be most concentrated in the wine at this point, so bottling then will capture or seal it). Where vine pests need to be controlled in biodynamic farming, a number of the pests are collected, burnt, and their ashes scattered around the affected area to discourage future infestations. Biodynamic viticulture alone will not a great wine make: good viticultural and winemaking practices such as canopy management and cellar hygiene are also essential. Biodynamic winemaking standards are similar to those used for organic wine, but impose stricter guidelines regarding enrichment, nutrient additions, the use of energy-intensive practices (eg pasteurization), micro-oxygenation, and recyclable packaging. In 2013 over 700 vineyards worldwide comprising more than 10,000 ha/24,710 acres were certified biodynamic, either by the German-based Demeter International organization which de facto controls the Biodynamic (with a capital B) agricultural trademark, or by the wine-only and French-based Syndicat International des Vignerons en Culture Bio-dynamique (Biodyvin), or by Australia’s government, which, uniquely, has its own biodynamic rulebook. Biodynamic vineyards range in size from a handful of hectares to several hundred. Vineyards whose biodynamic conversion proved catalytic either locally or further afield, in addition to those mentioned above, include Nicolas Joly in Savennières (1985), Jean-Pierre Fleury in Champagne (1989), James Millton in New Zealand (1989), Ch Romanin in Provence (1990), Guy Bossard in Muscadet (1992), Michel Grisard in Savoie (1994), the Fetzer and Frey families in California (mid 1990s), Cazes in Roussillon (1998), Nikolaihof in Austria (1998), Álvaro Espinoza in Chile (1999), Cooper Mountain in Oregon (1999), Reyneke in South Africa (2000), Valgiano in Tuscany (2001), Comte Abbatucci in Corsica (2002), Stéphane Tissot in the Jura (2004), Domaine Vacheron in Sancerre (2004), Ch Pontet-Canet in Bordeaux (2005), Dr Bürklin-Wolf in Germany (2005), Cullen in Western Australia (2005), Noemía in Argentina (2006), and Southbrook in Canada (2008). Despite scepticism in some quarters, biodynamic growers are becoming less reticent about their biodynamic practices, and increasing numbers of organic growers now claim to use some (usually the less esoteric) elements of biodynamics.
Biological Viticulture
a loose term since all viticulture involves biology, but for more details of the general philosophy implied. In France, many organic wines are sold as vins biologiques.
Climate
Long-term weather pattern of an area, and an extremely important variable in the winemaking equation. For more details, see macroclimate in particular, but also climate classification, climate change, continentality, cool-climate viticulture, latitude, mediterranean climate, rainfall, sunlight, temperate, temperature, temperature variability, and, importantly, climate and wine quality.
Continental
Climate is one with a high degree of continentality, defined for any place as the difference between the average mean temperature of its hottest month and that of its coldest month. Climates with a wide annual range are called continental; those with a narrow range, maritime. The former tend to be in the interiors of the larger continents; the latter, near oceans or other large water bodies. The most continental viticultural climates are those of central and eastern Europe, together with inland northern America (see russia and canada, for example). The European west coastal and most Mediterranean viticultural regions rank as intermediate, while the most maritime viticultural climate of all is that of madeira. All viticultural regions of the southern hemisphere, even those well inland, are classed (in this sense) as maritime. That is because the total land mass of the southern hemisphere is small relative to that of the oceans, which thus dominate temperatures. The rapid autumn temperature drop in continental climates means that ripening can be precarious. vintage variation therefore tends to be marked, and the effects of high yields on ripening and wine quality are probably more evident than in maritime climates when autumn temperatures drop slowly, and ripening is relatively assured. Cool maritime climates such as those of england and wales, on the other hand, can result in viticultural problems due to insufficient warmth during flowering and fruit set. European experience shows that ideal continental seasons can lead to superb wines when combined with appropriate cropping levels. Against that, maritime climates that are warm and sunny enough during flowering and setting can probably produce good quality more reliably, and thus have practical advantages for commercial viticulture.
Maritime Climate
The opposite of a continental climate, has a relatively narrow annual range of temperatures. Places with a maritime climate tend to be near oceans or other large bodies of water. Compared with nearby inland regions, spring temperatures tend to be lower, autumn temperatures higher, because effectively water masses gain and lose heat more slowly than land masses. There is also less difference between daily maximum and minimum in summer.
Mediterranean Climate
A climate type characterized by warm, dry, sunny summers and mostly mild, wet winters. It occurs throughout the Mediterranean basin, on the west coast of the United States, in Chile, southern and south western Australia, and the Cape Province of South Africa. The autumn and spring seasons range from mostly dry on the hot, equatorial fringes bordering deserts, to wet at the poleward fringes, where Mediterranean climates merge into those with a more or less uniform rainfall distribution as in central and western Europe. Mediterranean climates have some distinct advantages for viticulture over uniform or summer-rainfall climates, provided that supplementary irrigation can be given as needed. Sunshine is mostly more reliable and generous. There is less risk of rainfall in the growing season and of excessive rainfall during ripening and harvest. As a result of these rainfall patterns, the risk of fungal diseases is generally lower. And to the extent that many Mediterranean climates have the disadvantages of low humidity and high temperatures during the ripening period, precise vineyard site selection can help to minimize these disadvantages, by seeking out cooler coastal or high-elevation sites, for example. Further favouring Mediterranean climates is the fact that some of the main advances in both vineyard management and winemaking technology have particular application there. drip irrigation in a summer-dry climate allows a degree of control over soil water availability and vine vigour, and permits the use of mesoclimates and soils (see soil and wine quality) that were too dry for viticulture before. Improved canopy management has at least as great an application as in other climates.
Cool- climate viticulture
And warm-climate viticulture, are indefinite terms, depending on the speaker’s or writer’s viewpoint, but are probably applied most usefully to the coolest and warmest thirds of the climatic or geographic range used successfully for growing wine grapes. Intermediate climate viticulture (see below) lies between, while true hot-climate viticulture produces mainly table grapes and drying grapes, and cannot, in general, produce high-quality wine grapes of any kind. The term cold-climate viticulture is sometimes used to refer to those wine regions that experience winter freeze and where winter injury of vines can dominate viticultural practices. Major areas of cool-climate viticulture would certainly include the northern half of France (the loire, champagne, chablis, burgundy, and beaujolais,); england, luxembourg, germany, switzerland, denmark, and austria; in the US, the Lower Columbia Valley of washington and oregon, and the coolest coastal strip of northern California (carneros, anderson valley); the most southern vineyards of chile and some elevated vineyards of south africa; the South Island and southern North Island of new zealand; and in Australia, the whole of tasmania, small areas of the higher Adelaide hills in south australia, and southern victoria, and elevated land associated with the Great Dividing Range in the south east. Gladstones’s data (table 183) show all these to have regional average mean temperatures for the growing season (April to October inclusive in the northern hemisphere, October to April in the southern hemisphere) of below 16.0 °C/60.8 °F. Jackson and Schuster (1987) and Casteel (1992) deal specifically with this type of viticulture. The distinguishing characteristic of cool viticultural climates is that they will regularly ripen only early-maturing grape varieties such as chasselas, müller-thurgau, gewürztraminer, chardonnay, pinot noir, and gamay; and only in especially warm mesoclimates can varieties such as riesling, which ripens early to mid season, be ripened. ripening also tends to take place under cool to mild conditions. The combination leads to wines which, at their best, are fresh, delicate, and aromatic. Most are white or only pale red, because full development of anthocyanin pigments and tannins in the grape skins needs greater warmth. Other, warmer viticultural climates will be examined here for the sake of comparison. Intermediate climate viticulture is that with growing seasons long and warm enough for regular ripening of mid-season grape varieties such as cabernet franc, merlot, syrah (or Shiraz), and sangiovese, and late-mid-season varieties such as cabernet sauvignon and nebbiolo, to make mainly medium- to full-bodied red table wines. Typical regions are bordeaux and the northern rhône Valley in France; the rioja Alta in Spain; much of northern italy and tuscany; the intermediate and warmer coastal valleys of California, such as napa and sonoma; the north and east coasts of the North Island of New Zealand; Margaret River and the south coast of western australia; the Barossa Valley and hills, Padthaway, and Coonawarra in south australia; and much of central and southern victoria. Average mean growing season temperatures are in the range 16.0 to 18.5 °C (60.8 to 65.2 °F). Warm viticultural climates, if sunny enough, will ripen early and mid-season grape varieties to high sugar contents and make the best sweet, fortified wines. They will also ripen late-maturing grape varieties such as mourvèdre (Mataro), carignan, grenache, trebbiano, and clairette for making table wines. Examples are the south of France; the douro Valley of Portugal and the island of Madeira; the Adelaide district and McLaren Vale in south australia, the murray darling regions of South Australia and Victoria, and the Hunter Valley and Mudgee in new south wales in Australia. Corresponding average mean growing season temperatures are in the range 18.5 to 21 °C. Typical hot-climate viticultural regions are those producing table and drying grapes in greece and turkey, and the San Joaquin Valley of California. Growing season average mean temperatures are mostly 22 °C or higher. Subtropical and tropical viticulture for table grapes and wine, using mainly non-vinifera grape varieties, also falls into this temperature category. Relationships of temperature, particularly during ripening, to wine qualities are discussed under climate and wine quality.
Elevation
The height above mean sea level of a location such as a vineyard, often mistakenly referred to as altitude. Local elevation of vineyards above valley floors or flat land determines their air drainage and temperature relations, including liability to frost. The elevation of a vineyard can have important effects on its climate and therefore on its viticultural potential. Other things being equal, temperature falls by about 0.6 °C (1.1 °F) per 100 m (330 ft) greater height. Planting vineyards at higher elevations is commonly considered a means of avoiding the impact of increasing temperatures related to climate change. For example, torres in Cataluña is developing vineyards in the nearby Pyrenees, while Prager has been planting much higher land than previous generations in the Wachau. The lower temperatures at higher elevations retard both vine budbreak and, in particular, ripening. Small differences in elevation can have surprisingly big effects on wine quality and, indeed, on the ability of individual grape varieties to ripen at all. Becker refers to a major Rhine Valley study illustrating this. Lower temperatures can be further compounded by the generally greater rainfall and cloudiness at higher elevations. With the increased market emphasis on table wines since the 1960s, ever higher vineyard sites have been sought, especially in the world’s warmer wine regions. Examples include the Adelaide Hills in south australia, the Central Ranges of new south wales, Tupungato and other high-elevation plantings in argentina, the foothills of the Andes in chile, as well as the newer hillside vineyards of California, Sicily, and Greece. Some of these vineyards have been planted not just in search of cooler temperatures, but to escape the deeper, more fertile soils of the valley floors and to achieve vine balance in shallower, hillside soils. Elevated vineyards also experience more ultraviolet radiation, which is likely to increase quality because of stimulation of phenolic synthesis. Most of the world’s highest established vineyards are in Latin America but they are being challenged by new plantings in the Himalayas. Three of the world’s highest commercial vineyards are Swiss-born Donald Hess’s plantings in the northern province of Salta, Argentina. Colomé, near Molinos, is at 2,200–2,300 m (7,218–7,546 ft); El Arenal, Payogasta, is at 2,400–2,500 m (7,874–8,200 ft); Altura Máxima, also near Payogasta, is at 3,111 m (10,207 ft). bolivia has vines up to 2,850 m in the Cotagaita Valley. In the Himalayas in Asia, there are small commercial vineyards up to 2,900 m in the south west of china. A small vineyard planted in 2012 at 2,089 m (6,855 ft) in Big Bear in southern California’s ski country is claimed to be North America’s highest. The highest European vineyards are probably those of abona in the Canary Islands, which are at elevations up to 1,600 m/5,280 ft, although there are vines up to 1,150 m/3,770 ft and 1,250 m/4,100 ft in switzerland and aosta respectively.
Aspect
The direction in which a slope faces, an important characteristic of vineyard sites, especially in cool climates.
Latitude
Angular distance north or south of the equator, measured in degrees and minutes. The main northern hemisphere viticultural regions extend between 32 and 51 degrees north, and most of those in the southern hemisphere between 28 and 42 degrees south. Viticulture is spreading polewards and is likely to continue to do so due to climate change. Whereas ten years ago 52 degrees north in england (and Ireland) was around the northern limit, vines are now planted in norway and sweden, up to 59 degrees north. The southern extension is just over 46 degrees south in Central Otago, new zealand and it seems highly unlikely that the vine could thrive further south than this in South America. Some vines are also cultivated for wine production in tropical highlands or irrigated desert conditions as close to the equator as eight or nine degrees. Comparisons between hemispheres based purely on latitude are misleading. Northern hemisphere vineyards are on average warmer during the growing season at given latitudes, a fact partly related to their greater continentality. But even over the whole year, the northern hemisphere is on average warmer than the southern hemisphere at similar latitudes, partly because of the greater land mass and its disposition around the North Pole, and partly (in the case of western Europe) because of warming by the Gulf Stream. Similarly, comparisons between vineyard regions based on latitude can be misleading since temperature, which is influenced more by distance from the sea and elevation than by latitude, has a greater impact on vine physiology, phenology, and wine style. When wine regions with equal average mean temperatures during the growing season, or equal temperature summations, are compared, grapes tend to ripen more fully when grown at high latitudes, i.e. further from the equator. Alternatively, later maturing grape varieties can be ripened. The reasons for this phenomenon of great significance for wine quality remain unproven, but two main mechanisms have been proposed. There is speculation that because summers at higher latitudes have longer days, this may be an advantage for grape production and even wine style, but arguments for this are conjectural. It can be noted that high-latitude viticultural climates tend to have higher relative humidities and less day-to-day temperature variability during the growing season than those at low latitudes (apart from where the latter are coastal). Both factors have likely implications for ripening and for grape and wine quality. See climate and wine quality, humidity, temperature variability, and map under world production.
Topography
a term describing the land surface features of any area, which can have considerable implications for local climate and therefore for viticulture. The classic reference work by Geiger gives the most comprehensive general account of topographic effects on local climate. Topographic elements having the most influence on the climate are local elevation; slope; the relative isolation of hills; aspect; and proximity to water masses such as oceans, lakes, and rivers.
Topography- Local Elevation
Other things being equal, temperature falls by about 0.6 °C/1.1 °F per 100 m/330 ft greater elevation. This is known as the lapse rate.
Topography- Slope
At night, air is chilled by direct contact with a land surface which is rapidly losing heat by radiation. The chilled air, being denser, flows down slopes to the flat land or valleys below, and is replaced by warmer air from above the land surface. The turbulent surface air over slopes at moderate elevations is therefore usually warmer at night, and in the early morning, than that settled over the adjacent flats and valley floors. This band on a hill slope is known as its ‘thermal zone’, and especially in cool climates is valued for viticulture because of its enhanced ripening potential and length of frost-free period. The steeper the slope, the more pronounced is its thermal zone.
Topography- Relative isolation of hills
Thermal zones are strongest on isolated and projecting hills or mountains, because these have little or no external source of surface-chilled air. Cooled air from their own surfaces that slips away can be replaced only by totally unchilled air from above. The implications of this are discussed under climate and wine quality; see also terroir. Examples of viticulturally famous isolated hills include the hill of Corton at aloxe-corton in Burgundy; the Kaiserstuhl in baden; and, on a larger scale, the Montagne de Reims in champagne.
Topography- Aspect
Slopes which face the sun through much of the day (southerly aspects in the northern hemisphere, and northerly aspects in the southern hemisphere) are the warmest, and those facing away from the sun are the coolest. The influence of aspect is modified by other climate parameters. For example, the degree of daytime warming is increased by more sunshine and by protection from wind. Differences in soil temperature are important not only for nutrition of the vine, but also for growth and fruiting through export of the growth substance cytokinin to the vine tops. The climatic contrasts among aspects are greatest at high latitudes and in cooler vineyard regions, and also early and late in the vine-growing season. The steeper the slope, the more aspect will affect its climate. Easterly aspects of slopes facing the equator have the advantage that they are warmed earliest in the day, when soil and air temperatures are lowest. Notable examples of this are found in the côte d’or of Burgundy, and in the rhine Valley of Germany and Alsace. West-facing slopes can, however, induce higher daytime air temperatures because absorption of sunlight and warmer air temperatures are complementary. This is important in very cool climates.
Topography- Proximity to oceans, lakes and rivers
Water absorbs and stores large quantities of heat, with relatively little change in temperature because of the depth to which the heat penetrates, together with the high specific heat of water compared with rocks or dry soil. Its resulting temperature inertia greatly modifies the temperature regimes of adjacent land. Cool air from over the water is drawn to replace heated air rising over the land in the afternoons, while at night a reverse convection results from chilled air descending from the cold land surface and rising over the now relatively warm water. In some vineyard areas, these breezes may, in fact, be very strong winds if they are funnelled by mountains, as in the Salinas Valley in monterey, California. This daily alternating pattern of air circulation makes the climate adjacent to water bodies significantly more constant than it would otherwise be, in terms of both temperature and humidity. Both factors are important in climate and wine quality. There is also a reduced incidence of spring frosts and winter freeze injury in regions liable to these. Examples of this lake effect are found in new york state, in the vineyards of Ontario in canada, and around russia’s Black Sea coast. The effects of rivers and lakes are normally confined to their immediate valleys, but maritime influences can extend considerable distances inland from coasts in the form of land and sea breezes. Notable examples of the latter occur in the bordeaux region of France; the napa Valley and sonoma and other near-coastal regions of California; and the hunter valley and swan valley of Australia’s east and west coasts respectively.
Air drainage
Important topographical and hence climatological consideration in vineyard site selection. Cold air flows, or ‘drains’, downhill and so a continuous slope or hillside is much less prone to frost and winter freeze than a hollow. In regions at risk from these phenomena, zones which accumulate cold air should be avoided as vineyard sites. In general, a vineyard site near the top of a free-standing hill is ideal since no cold air is imported from above.
Berry
Botanical term for a class of fleshy fruit lacking a stony layer, so that all of the fruit wall is fleshy or pulpy. The grape berry, popularly known as the grape, is a prime example. It consists of two carpels, denoted by its two locules (internal spaces) in each of which are borne two ovules which may develop into seeds, giving in most cases a maximum of four seeds per berry.
Berry Size
Is considered by many to be a factor in wine quality. It is often said that smaller berries contribute to better wine quality, especially for red wines, since anthocyanins, phenolics, and flavour compounds are mostly contained in the skins. Smaller berries’ higher surface-to-volume ratio results in a higher concentration of these skin compounds in the juice and hence in the wine. However, there are few scientific studies that confirm this and some consider a link between berry size and wine quality to be a myth. Good-quality wine grape varieties typically have small berries, at least compared with both lower-quality varieties and table grapes. The average weight of a premium wine grape at full ripeness is 1 to 2 g, whereas others weigh 3 to 10 g/0.35 oz. These values doubtless represent the selection of vine varieties for their end use, which has continued for centuries. This fact in itself would seem to support the idea that small berries are a prerequisite for premium wine production. It is not the case, however, that any vineyard management practice which leads to smaller berries will necessarily improve wine quality. Certainly, water stress causes small berries, although some of the effects on wine quality may be the result of water stress on vine physiology rather than the direct result of small berries. The other simple means of reducing berry size is pruning to many buds in winter, but this is contrary to the principles of balanced pruning. Such pruning is likely to reduce wine quality since the vine may struggle to ripen grapes with insufficient leaf area for efficient photosynthesis. Controlled studies in California (with Cabernet Sauvignon) and Australia (with Shiraz and Pinot Noir) have shown that smaller berries do not necessarily make better wine. These studies concluded that it is the vineyard factors which make berries small, water stress in particular, which contribute directly to wine quality, not the small berries in themselves.
Acids
Members of a group of chemical compounds which are responsible for the sharp or sour taste of all drinks and foods, including wine. The most important acids contained in grapes are tartaric acid and, in slightly lower concentrations, malic acid. Malic acid occurs in many different plants and fruits, but vines are among the very few plants with large concentrations of tartaric acid in their fruit. The principal acid component in most plants is citric acid but vinifera vines are also unusual among plants in accumulating only very small amounts of citric acid. Grapes contain a large number of acids other than their major constituents, tartaric and malic acids. Present in low concentrations are several of the fatty acids, of which the most common is acetic acid, arising from the metabolic processes of fruit ripening. Some other acids involved in the growth of vines accumulate in the berry in very small amounts and some of these persist into the wine. Other acids found in wines, while possibly present in traces in grapes, are formed mainly during fermentation. Among those present in the largest concentrations are lactic acid, succinic acid, and carbonic acid. Various acids are also occasionally added during winemaking. (See ascorbic acid, sorbic acid, and sulfurous acid, which is sulfur dioxide.) Acids are important in wine not just because, in moderation, they make it taste refreshing, but also because they prevent the growth of harmful bacteria and spoilage yeasts such as brettanomyces and can keep it microbiologically stable. Most bacteria, and all of those of greatest danger to man, are incapable of living in distinctly acid solutions such as wines. Two groups of bacteria are major exceptions to this rule, however, the acetobacter and the various lactic acid bacteria. A wine’s concentration of acids is called its acidity, which can be measured in various ways. Acidity is closely, if inversely, related to ph.
Tartaric Acid
The most important of the acids found in grapes and wine. Of all the natural organic acids found in plants, this is one of the rarer. The grape is the only fruit of significance that is a tartrate accumulator, and yet it is of critical importance to the winemaker because of the major part it plays in the taste of the wine. Furthermore, because tartaric acid exists in wine partially as the intact acid and partially as the acid tartrate, or bitartrate ion, it is the principal component of the mixture of acids and salts that constitutes wine’s all-important buffer system and maintains the stability of its acidity and colour. Tartaric acid is of further interest because its potassium acid salt, potassium tartrate or cream of tartar, while being moderately soluble in grape juice, is only partially soluble in alcoholic solutions such as wine. Most winemakers therefore try to ensure that no excess tartrates remain in the wine when it is bottled lest these crystals frighten less sophisticated consumers by their resemblance to glass shards. See tartrates for more on this important by-product of the winemaking process. Grapes and the resultant wines vary considerably in their concentrations of tartaric acid. Among the thousands of cultivated vine varieties, some are noted for their high concentrations of tartaric acid, while others are remarkably bland. In general, wine grapes have higher concentrations of acids than table grapes. Among wine grape varieties, however, there is considerable variation in concentrations of the two principal acids: tartaric acid and malic acid. Palomino, the sherry grape, for example, is particularly high in tartaric acid, while the Pinot Noir of Burgundy and Malbec, or Côt, are relatively low in tartaric. The relative amounts of these two acids that are present in grapes, which varies with vintage, do not necessarily govern the relative amounts in wines, however. Precipitation of potassium acid tartrate, as outlined above, limits total tartaric acid concentration, while malic acid is frequently decomposed by malolactic conversion. Wines that have not undergone this conversion generally have slightly more tartaric acid than malic acid, while those which have undergone this ‘softening’ process usually have many more times tartaric than malic acid; they are also more stable. Weather and soil, as well as grape variety, affect the amounts of different acids in the grape and wine. Cooler climates in general favour higher concentrations of acids and lower levels of potassium in the grape skins. Malic acid is much more effectively decomposed by excessive heat during the grape ripening period than is tartaric acid. Soils deficient in potassium, or potash, may result in grapes of high acid concentration and low ph because low potassium levels allow greater concentrations of acid tartrate ion to stay in solution. Another curious difference is that tartrate levels are very high in grape flowers. Tartaric acid is not respired during ripening, meaning that its amount per berry stays relatively constant during berry ripening. More than half of the tartrate in ripe berries can be present as a salt. The proportion of free to salt form varies with variety and the concentration of metal cations in the juice; potassium is by far the most abundant.
Magic Acid
One of the two principal organic acids of grapes and wines. Its name comes from malum, Latin for apple, the fruit in which it was first identified by early scientists. Present in nearly all fruits and berries, malic acid is now known to be one of the compounds involved in the complicated cycles of reactions by which plants and animals obtain the energy necessary for life. One of these cycles of reactions is known as the citric acid, Krebs, or tricarboxylic acid cycle and its elucidation was one of the outstanding triumphs of biochemistry. Another, which comes into play during the final stages of ripening in many fruits, including grapes, causes the decomposition of malic acid. When all of the malic acid has been used up in this latter series of reactions, the fruit becomes overripe, or senescent. The malic acid decomposing reaction is much more rapid in hot summer temperatures, probably because of the more rapid respiration of malate in the berry. This is, at least in part, one reason for the lower total acid concentrations in grapes grown in warmer regions. It accumulates in young grape berries reaching high levels at about veraison—sometimes as high as 20 g/l—but, as ripening progresses, the level of malate declines to concentrations of between 1 and 9 g/l when the grapes are ripe. This large range in ripe grapes is an important source of variation in quality and style. Tartaric acid, the other main grape acid, does not participate in several of the reaction pathways in which malic acid is an essential component, which is why the hotter the summer, the lower the likely proportion of malic acid in the grapes. Malic acid’s different chemical structure allows it to participate in many more of the enzymatic reactions involved in living systems than tartaric acid because it can be pumped across plant membranes serving as a transportable energy source. Because the concentrations of tartaric acid are relatively and desirably stable, attention is given to the tartrate/malate (T/M) ratio, which varies from about 1 to 6 and is characteristic for each grape variety. High malate varieties, with a low ratio, are desirable for hot districts and examples are sylvaner, colombard, barbera, and carignan. Malic acid is lost not just through the citric acid cycle, and through other reaction cycles during grape ripening, but also in many cases as a result of malolactic conversion. Temperatures of 18–22 °C/64–72 °F encourage the lactic acid bacteria involved in malolactic conversion. The winemaker can exercise some control over this loss of malic acid if necessary, however, since the growth and activity of these organisms can be slowed or inhibited by moderate concentrations of sulfur dioxide. In addition, since the lactic acid bacteria responsible for malolactic conversion require many micronutrients (vitamins, growth factors, nitrogenous compounds), early and thorough separation of the new wine from its lees can inhibit bacterial activity and preserve malic acid. Malic acid is available commercially for use in acidifying foods and beverages and in numerous industrial processes. At one time it was isolated from fruits and other plant tissues but is more usually synthesized from another organic acid today.
Anthocyanins
Members of a complex group of natural phenolic glycosides responsible for the colour of black and red grapes. They are also responsible for the colour of red wines, both as wine components and as precursors of pigmented tannins and other derived pigments which are formed through reactions of anthocyanins with other wine components. Anthocyanins are common in the plant world and are responsible for the red to blue colours of leaves, fruits, and flowers. The word comes from anthos, Greek for ‘flower’, together with the Greek-derived ‘cyan’ blue. The particular anthocyanins found in grapes are limited in number, with mixtures of pigment molecules varying from species to species and from grape variety to grape variety. Indeed, chemical determination of the particular mixture of pigments present in an unidentified grape berry can aid vine identification. Pure vinifera varieties have mostly anthocyanin pigments with only one molecule of glucose (monoglucosides), while many of the american vines used in breeding rootstocks and american hybrids also have significant amounts of anthocyanins with two molecules of glucose (diglucosides; a fact which greatly aided detection of non-V. vinifera wine in France in the mid 20th century). Anthocyanins have another important characteristic. They are capable of changing form, depending upon the ph, or degree of acidity, of the medium in which they are dissolved, the different forms being red, blue, and colourless. In general, the more acid the grape juice or wine, the greater the degree of ionization of the anthocyanins (giving a higher proportion of the red flavylium cation), and the brighter red the colour; as the acidity decreases, the proportion of colourless and blue forms increases. In mildly acidic conditions, anthocyanins are also bleached by sulfur dioxide. At wine pH values, grape anthocyanins should be mostly in colourless forms unless the pigments are stabilized by co-pigmentation or through conversion to derived pigments including pigmented tannins. The anthocyanin pigments are formed in the grapevine by a sequence of metabolic steps and are first visible when the berry begins to expand. The onset of this stage in the vine’s metabolism is called veraison and is characterized by rapid growth and accumulation of sugar in the berry together with the first flush of colour in the berries. The concentration of the pigments in the grape skin increases as the level of sugar increases in the grapes during ripening. The increase is intensified if sunlight falls on the berries, that is, if the berries are in an open canopy microclimate. Anthocyanin production during ripening is very temperature-dependent and is also strongly influenced by the macroclimate. During veraison the anthocyanin pigments are formed and sequestered in the berry skins’ outer cell layers in all but a few dark-berried grape varieties which have a portion of the pigment present in the pulp of the berry as well as in the skin (see teinturiers). One important operation during the fermentation of most red wines, therefore, is to transfer the anthocyanin pigments from the skin cells to the wine. Colour transfer is achieved by keeping the skins adequately mixed with the fermenting wine. One might reasonably expect that the pigments in the new wine would be identical to those found in the grape skin. This may be the case for a few hours, but once the anthocyanins are mixed with the other phenolics as well as the many products of fermentation, they begin a series of reactions leading to a great diversity of derived pigments and colourless molecules. Derived pigments are classically assimilated to pigmented tannins arising from the addition of tannins to anthocyanins, either directly or through condensation reactions with aldehydes. However, they also include rather small molecules formed by the reaction of anthocyanins with other wine constituents such as acetaldehyde or pyruvic acid, or hydroxycinnamic acid derivatives. Moreover, most of these reaction products are themselves unstable and the list of derived pigments found in wine keeps expanding, covering a wide range of colours. Within a few years, only traces of the relatively simple monomeric anthocyanins remain. With wine ageing, polymers containing anthocyanin molecules may become larger and form aggregates so that some of them exceed their solubility in the wine and are precipitated as sediment.
Flavour Precursors
Include glycosides, or sugar derivatives, of compounds that would otherwise be flavour-active. These flavourless compounds occur naturally in grapes (and many other fruits) as products of the normal metabolic activity of the fruit, and they are both numerous and more abundant than the free flavour compounds. Their importance to wine comes from their ability to release and so augment the level of flavour compounds, some positive, some less so. In the case of glycosides, this release is by hydrolysis. This may be a prolonged process during ageing, for example, or one accelerated through the use of enzymes in the winemaking process. Both chemical and sensory studies at the australian wine research institute have demonstrated that flavour precursors are important in development of varietal flavours and bouquet in wines. Because many flavour precursors are glycosides, quantification of this class of compound through measures of glycosyl-glucose in grapes has been suggested as an indicator of grape quality although research is underway to find quicker analytical techniques. A new category of grape flavour precursor, involving the coupling (or conjugation) of a volatile thiol compound to the amino acid cysteine, was discovered by Professor Denis Dubourdieu’s research group at bordeaux University in 1998. The action of yeasts during alcoholic fermentation serves to free some of the highly potent thiol compounds from their S-cysteine conjugated precursor form.
Monoterpenes
Have ten carbon atoms and are members of the group of natural products called terpenoids. Monoterpenes are major contributors to the characteristic flavour properties of muscat grapes and wines, and contribute to the floral aromas of many non-Muscat wines such as riesling. Individual monoterpenes that are found in grapes and contribute to the attractive flavour properties of wines include the alcohols geraniol, nerol, linalool, and citronellol, although more than 40 have now been reported. Monoterpenes were among the first grape and wine flavour compounds to be elucidated, and the first to be discovered in glycosylated form as flavour precursors.
Phenolics
Very large group of highly reactive chemical compounds of which phenol (C6H5OH) is the basic building block. These include many natural colour pigments such as the anthocyanins of fruit and dark-skinned grapes, most natural vegetable tannins such as occur in grapes, and many flavour compounds. The terms polyphenolics or polyphenols are often used as synonyms of phenolics but should be restricted to plant secondary metabolites featuring more than one phenolic ring and derived from specific metabolic pathways, as Quideau et al. explain.
Phenolics- In Grapes
These compounds occur in great profusion in grapes. They are particularly rich in stems, seeds, and skins but also occur in juice and pulp. The concentration of phenolics in grape skins increases if the berries are exposed to sunlight, in particular to ultraviolet radiation, because the phenolic compounds act as a natural sunscreen. Phenolic compounds strongly absorb ultraviolet light, a fact used in their laboratory analysis. Manipulating fruit exposure in the vineyard is therefore a way to affect the phenolic content of berries and wine made from them. See canopy management. Many hundreds of compounds belong to the phenolic category, and they can initially be classified as either non-flavonoid or flavonoid. The former include compounds derived from cinnamic and benzoic acids (one of the most abundant in grape juice is caftaric acid, the tartrate ester of caffeic acid) and stilbenes such as resveratrol. Flavonoids encompass catechins and their polymers, called proanthocyanidins or condensed tannins, which are an essential part of the taste and flavour of grapes and other fruits, and pigments, including flavonols and anthocyanins. With a few exceptions, such as the phenolic amino acid tyrosine that is a constituent of proteins, phenolics belong to the general group known as secondary metabolites, meaning that they are not involved in the primary metabolism of the plant. They are highly water-soluble and are secreted into the berry vacuole, many as glycosides, and some are flavour precursors or precursors of off-flavours.
Phenolics- In Wines
Phenolic acids (especially cinnamic acids) are the major phenolics in grape pulp and juice, and thus in white wines made without skin contact. Anthocyanins are localized only in the skins, except in red-fleshed teinturiers, so that red winemaking requires a maceration phase to extract them into the juice. Flavonols, which are constituents of skins, stems, and leaves, as well as catechins and tannins, which are also present in seeds, are simultaneously extracted. Alcohol, produced by fermentation, greatly speeds up this extraction process. Additional phenolics (including gallotannins and ellagitannins as well as flavour compounds such as vanillin) may also be present in wine as a result of barrel ageing, the use of oak chips, or the addition of oenological tannins. Once extracted into the wine, the anthocyanins, catechins, and tannins are gradually converted to various types of derivatives, including pigmented tannins. These reactions are responsible for the colour and taste changes observed during wine ageing. Catechins and proanthocyanidin oligomers taste bitter, while larger tannins are responsible for the mouth-puckering astringency in young wines. As the wine ages, tannins and their derivatives form larger and larger particles through aggregation and complexation with other molecules such as proteins and polysaccharides. This may result in the development of haze and sediments and other technological problems (e.g. clogging of filtration membranes, adsorption on tank surfaces). A significant number of flavour precursors as well as flavour compounds also have the phenol structure. Examples of these are vanillin, the key aroma compound of the vanilla bean, and raspberry ketone, the impact compound of raspberries. An ester, methyl salicylate, familiar as oil of wintergreen, is also a phenolic compound. These and many others are either grape constituents or are produced as trace components during alcoholic fermentation and by glycoside hydrolysis during the subsequent processing and ageing phases.
Phenolics- In Tasting Terms
Phenolic is also sometimes used, imprecisely, as a pejorative tasting term, to describe (usually white) wines which display an excess of phenolics by tasting astringent or bitter.
Phenolics- As health benefits
It is in its high phenolics content that red wine is distinguished from white, and it is thought that it may well be the antioxidative properties of phenolics which reduce the incidence of heart disease among those who consume moderate amounts of red wine.
Pigmented Tannins
Also called polymeric pigments, are responsible for the colour of red wines, together with anthocyanins, which are the phenolic red pigments of dark-skinned grapes. Pigmented tannins comprise a great diversity of molecular species formed by the reactions of anthocyanins with non-pigmented catechins, proanthocyanidins (i.e. condensed tannins from grapes), and ellagitannins (i.e. hydrolysable tannins extracted from barrels or added as components of some oenological tannins), under the influence of acids and oxygen. Their formation begins in the course of maceration, and then progresses throughout the ageing of a red wine, so that the grape anthocyanins as individual molecular species make only a transitory and ever-diminishing contribution to the colour of a red wine. Although this process has been known for over thirty years, some of the structures postulated for pigmented tannins have only recently been shown to form in wine, owing to progress in the development of analytical techniques, whereas others have not yet been confirmed. Besides, several so far unsuspected reaction processes and products have been unravelled in the last few years. Formation of pigmented tannins occurs through both direct addition reactions between anthocyanins and tannins and reactions involving fermentation products such as acetaldehyde and pyruvic acid. The nature and amounts of the resulting products depend on the nature and proportions of the phenolics present and the relative kinetics of the various reactions. Physico-chemical parameters such as pH and temperature and the presence of oxygen, of yeast metabolites, and of co-factors, such as metal ions, also affect the type and/or kinetics of the reactions. Colour changes, from the purple nuance of young wines towards the red-brown tint of mature wine, are classically ascribed to the conversion of anthocyanins to pigmented tannins. However, pigmented tannins cover a wide range of colours, from orange to purple and blue. Besides, anthocyanin reactions also yield lower molecular weight orange pigments which are not pigmented tannins. Reactions of tannins under oxidative conditions also lead to brown-orange pigments that do not derive from anthocyanins. Most of these pigments show increased colour stability with respect to hydration and sulfite bleaching compared with anthocyanins but this property is neither characteristic of nor specific to pigmented tannins. Known pigments account for only a small proportion of wine colour, meaning that most pigmented tannins are of analytically intractable nature, due to their multiplicity and diversity of structure and the transient nature of individual molecular species as they equilibrate among each other. There is also conjecture about interactions of pigmented tannins with proteins and polysaccharides and the influence of such putative interactions on the properties of the pigmented tannins. Experience has also shown that the formation of pigmented tannins, as well as conferring stability on the colour of a red wine (for decades, in favourable circumstances) also modulates the astringency of the very high concentration of phenolics of the wine, improving its texture and other taste properties. The desirable effects of pigmented tannins on mouthfeel are well illustrated by a comparison of the taste properties of a red wine with those of a white wine made, like a red wine, with extensive maceration. Such highly tannic white wines (except for the few made deliberately in this way; see orange wine, qvevri, and skin-fermented whites for examples) are not just unattractive, but crude and coarse on the palate; furthermore, they do not improve with age but remain tannic and undrinkable. In contrast, the pigmented tannins of the red wine make it palatable and soft with good ageing characteristics, and this despite the fact that their presence increases further the phenolic and tannin polymer content of the red wine relative to that of its macerated white wine counterpart. Changes in astringency taking place during red wine ageing are usually attributed to an increase of tannin molecular weight as a result of the formation of co-polymers with anthocyanins since larger polyphenolic species have been claimed to be insoluble and thus non-astringent. However, recent studies have shown that tannin solubility does not decrease with molecular weight and that astringency in fact increases with the tannin size. Besides, tannin reactions in wine do not only yield larger polymers but also lead to lower molecular weight species. The latter reactions may contribute to the decrease of astringency observed during wine ageing. Nevertheless, the taste of pigmented tannins and the effect of incorporating anthocyanin units in a tannin structure on its astringency remain to be investigated.
Fructose
Is, with glucose, one of the two principal sugars of the grape and sweet wines. It is a six-carbon atom sugar, or a hexose. Common table sugar, sucrose, is made up of one molecule of fructose and one of glucose. The grapevine leaf in the presence of sunlight, water, and carbon dioxide makes sucrose by a complicated series of steps called collectively photosynthesis. The sucrose is transferred in the plant sap from the leaf to the grape berry. There the sucrose is split into fructose and glucose, the forms in which it is stored in the berry. The vine is unusual among fruiting plants in the extent to which it is capable of concentrating the two sugars fructose and glucose in its berries; sugars routinely represent 18–25% of grape juice weight, while 12% is the norm in apple and pear juice. Fructose accumulates in the grape berry along with glucose but at lower concentrations during the early stages. However, at ripeness, and especially when grapes are overripe, fructose levels often exceed glucose. The glucose–fructose ratio is thus an indicator of grape ripening (roughly 1:5 at veraison but less than 1 at full ripeness). This is important because fructose is remarkable in that it has between 1.3 and 1.8 times the sweetening power of either glucose or sucrose (which has led to its manufacture in large quantities for use in so-called diet foods). During fermentation of grape juice, both fructose and glucose are consumed. Furthermore, in the acid and enzymic environment of grape juice, any sucrose present is split into its constituent parts, fructose and glucose, and will consequently be fermented. With selected strains of wine yeasts, nearly all the fructose and glucose are converted to alcohol and carbon dioxide, leaving the wine with only traces of fermentable sugars.
Glucose
Is with fructose one of the two principal sugars of the grape and of sweet wines. Like fructose, it is a six-carbon-atom sugar, or a hexose. The two major sugars that accumulate in grapes occur in about equal amounts; at the beginning of ripening, glucose exceeds fructose (up to fivefold), but in wines made with overripe grapes there is less glucose than fructose at the end of fermentation. Glucose also serves a very important function as the major sugar used by the vine for forming glycosides. Common table sugar, sucrose, is made up of one molecule of glucose and one of fructose. See fructose for details of the unusual relationship between these sugars and the grape.
Sucrose
Cane sugar, the most common of the sugars, is ubiquitous in plants because it is the preferred compound for phloem translocation of energy and carbon around the plant. Sucrose consists of a glucose molecule joined to a fructose molecule. Breakdown (hydrolysis) of sucrose is achieved readily by the enzyme invertase, which ‘inverts’ it to these hexoses. Invertase in the vine occurs in cell wall spaces but not in those of the leaf, which is why sucrose is confined in vines mainly to leaves and phloem tubes. Invertase is abundant in grape berries both in the cell walls and in the vacuoles; hence the sugars that accumulate in berries are mainly glucose and fructose.
Sugar in Grapes
The raison d’être of viticulture. The central role of sugar in the utility of grapes for wine, table grapes, drying grapes, and other viticultural products cannot be over-emphasized. sugars produce sweetness and ferment to produce ethanol, both of which are valued by humans. However, of all sugary plant produce, none yields a commodity as highly valued or widely produced as grape wine. The free sugar that accumulates in grapes, glucose and fructose, is the result of translocation of sucrose photosynthesized in leaves and moved via phloem tubes into grape berries during ripening, where it is inverted (hydrolysed) by the enzyme invertase. The astonishing feature of grapes is that this accumulation occurs at the same time as water is accumulating in the berry, yet concentration is also increasing; in other words, sugar is increasing proportionately more than water. Other phloem-provided sucrose moves throughout the vine dispensing energy and the carbon skeletons for all organic molecules throughout the vine. Additionally, sugar is used for carbon storage, as starch in wood, and for the formation of glycosides in the storage of secondary metabolites in vacuoles of cells. While total sugar content is a key factor in determining optimum ripeness of grapes for wine, sugar–acid balance is equally important; hence the use of sugar–acid ratio as a guide to the date of harvest.
Grape Juice Composition
The relative proportions of the compounds that make up grape juice are constantly changing as the berries ripen, so the time of harvest greatly affects composition. Most of the sugary solution that results when grapes are squeezed or crushed derives from the contents of the vacuoles of the cells of the pulp or flesh, although heavy crushing and pressing adds further solution from vacuoles of the skin and vascular strands, thereby mixing many different compounds into the must. Thus the composition of the juice that issues when berries are crushed changes with the pressure and time of crushing; the first, free-run juice has fewest suspended solids and skin extracts; further pressing yields juice with more phenolics and potassium salts, and hence lower total acidity. Fermentation of juice with skins present, as in red winemaking, yields still more flavour compounds and pigments that are enriched in the cells of the skin.
Frost
The ice crystals formed by freezing of water vapour on objects which have cooled below 0 °C/32 °F. Such frosts are known as white frosts, or hoar frosts. Black frosts cause freezing and extensive killing of plant tissue itself, without any necessary hoar formation. Frost is a major viticultural problem as it can damage and kill shoots and fruit, in spring and autumn. frost protection is expensive and not always effective; see also frost damage. Frost frequencies are, in many studies, imputed arbitrarily from weather records. Temperatures as recorded in the standard Stevenson screen used by meteorologists, at 1.25 m/4.1 ft above the ground, are always higher than at ground level. A screen temperature of 2.2 °C/36 °F is normally assumed to indicate a light ground frost, and one of 0 °C a heavy ground frost. Temperatures at vine height of −1 °C or lower after budbreak in spring will usually cause serious injury to the young shoots. Even ‘light’ frosts can often cause damage somewhere in the vineyard, because their incidence tends to be patchy, depending on topography. Geiger covers this aspect in detail. Two main types of frost are distinguished: radiation and advection. Radiation frost occurs typically on still, dry, cloudless nights. Without cloud, mist, or much water vapour to absorb and trap heat radiated from the ground and plant tissues, heat escapes freely to space and rapid surface cooling results. Air in immediate contact with these surfaces then becomes cooled. The coldest air, being densest, remains or collects close to the ground and in depressions. Lowest air temperatures in the early morning on flat land are at 5 to 15 cm/2–5 in above ground, rising with height to a relatively warm ‘inversion’ layer, commonly some 15 to 30 m/100 ft above, beyond which temperatures gradually fall again with elevation. This pool of cold, dense air close to the ground is stable unless dispersed by wind, or unless it can flow away by gravity to still lower regions. Advective frosts result from such flows of already chilled air from elsewhere. They can originate locally, following valleys or other natural courses of air drainage, or arrive from up to several hundreds or perhaps thousands of kilometres away.
Smudge Pot
Burner, usually fuelled with oil, lit in frost-prone parts of an orchard or vineyard on still nights when lethal frost seems imminent to create air convection currents which mix relatively warm upper air with the chilled air settled at ground level. They have lost favour because of the numbers of pots required, not to mention fuel, smoke, lost sleep, and the general inconvenience of operating them in the cold darkness of the early morning. Other approaches to frost protection are available.
Sprinklers
Are used for irrigation, and in some vineyards to control frost (the water freezes to form a protective coating of ice round the young vine buds). Sprinkler irrigation has largely been replaced by drip irrigation, which uses much less water, and does not leave wet leaves vulnerable to fungal diseases and possible salinity damage. It is important to avoid waterlogging, which can readily cause injury to the newly growing roots. It has also been used in hot regions of Australia for vineyard cooling, by operating the system intermittently during the hottest part of the day, but this is not economical and wastes water.
Hail
Frozen raindrops or ice bodies built up by accretion, typically falling in thunderstorms. To the normal ill effects of heavy summer rainfall is added direct physical damage to the vines and fruit. That to the vines ranges from ripping and stripping of the leaves to bruising and breaking of the young stems: effects which can carry over to the following season or even much longer. Damage to young bunches may destroy or at best reduce the crop, although compensatory growth of the remaining berries may minimize the effects on final yield. Hail damage while berries are ripening, on the other hand, is invariably a disaster. Smashed berries are prey to rot and ferment on the vine, rendering even undamaged parts of the bunches unusable. burgundy is particularly and apparently increasingly prone to hail damage, as is Mendoza in argentina. Hail is said to cost French agriculture more than half a billion euros a year. Hailstorms characteristically follow irregular but well-defined pathways through an area, sometimes devastating parts of a vineyard but leaving other parts untouched. Local topography may result in a tendency for the storms to follow preferred pathways, but largely their incidence is unpredictable. Various prevention techniques have been tried, including seeding the clouds with silver iodide or dry ice, from planes or cannon, to reduce the size of the hailstones so that some melt before they reach the ground, and using hail cannon that generate shock waves intended to disrupt the formation of hail. Covering the vines with netting is another laborious and expensive option which reduces the impact of hailstones but also reduces the amount of sunlight reaching the vines—desirable only in the hottest wine regions. The technologies can hardly be described as proven, but have found supporters among vine-growers understandably desperate to protect their hard-won crops. Insurance against hail is rarely cost-effective.
Powdery Mildew (Oidium)- Fungal Diseases
Native to North America, the Uncinula necator fungus has spread worldwide, and thrives even in humid yet dry conditions—rainfall is actually a detriment to the survival of its spores. The fungus, during its anamorph stage, is known as Oidium tuckerii. Powdery mildew affects all green parts of the plant, marking grapes, leaves, and shoots with its dusty white mildew growth. It prefers densely shaded canopies and overcast weather, and greatly inhibits bunch development and ripening. If infected prior to flowering, yields will be reduced; if infected after fruit set, berries will struggle to achieve veraison and reach full size. Fruit affected by powdery mildew is universally avoided in the winemaking process, as it creates off-flavors in the wine. Powdery mildew, first recorded in England in 1847, spread quickly throughout the Vitis vinifera vineyards of Europe but was soon controlled by applications of sulfur and other fungicides.
Downy Mildew (Peronospora)- Fungal Diseases
Another fungal disease that emigrated to Europe on North American vine cuttings, downy mildew spread rampantly through France and the rest of Europe in the early 1880s. Plasmopara viticola, the agent of downy mildew, attacks the green portions of the vine, causing leaves to drop off the vine and limiting the vine’s ability to photosynthesize. The infection is first visible as an oil spot on vine leaves. As spores germinate a white, cottony growth develops on the underside of the leaves. The fungus survives the winter on fallen leaves in the soil, and its spores reach the vine again with the help of rain splatter in the spring. Arid regions prohibit its growth. The blue-staining Bordeaux Mixture, a spray of copper sulfate, water and lime, was developed by 1885 to prevent outbreaks of downy mildew.
Eutypa Dieback- Fungal Diseases
Also called dead arm, the disease is caused by the Eutypa lata fungus. Spores are carried by rain and enter the vine through pruning wounds. Common in Mediterranean climates, the disease is difficult to control as it affects a wide number of plants. Infected vines experience stunted shoot growth as the fungus releases toxins, and eventually an infected cane may die—the dead arm. This disease has a drastic effect on yield, but does not devalue the quality of the crop. In fact, Australia’s d’Arenberg ascribes a beneficial effect on quality to the dead arm, and markets its icon Shiraz under the disease’s nickname. A separate fungus, Phomopsis viticola, manifests as a similar disease.
Esca (Black Measles)- Fungal Diseases
One of the earliest known fungal grapevine diseases, Esca thrives in warmer climates but exists worldwide, and there is no known control or cure. Unlike other fungal diseases, Esca is the result of a complex of fungi, rather than a single organism. On young vines, the disease will weaken growth, affect berry development and discolor leaves; in hot weather an affected young vine may suddenly die. In older vines, the disease affects the wood, causing the interior of the trunk and arms to soften and rot from the inside—a condition that led ancient Romans to use Esca-infected tree trunks for firewood, as its spongy interior quickly caught fire. Mature, Esca-infected vines will rarely live past 30 years of age. The disease is exacerbated by rainfall and can be spread by wind or on the pruning shears of careless vineyard workers.
Black Rot- Fungal Diseases
Native to North America, Black Rot spread to Europe with the importation of phylloxera-resistant rootstocks in the late 1800s. The disease is caused by the Guignardia bidwelli fungus, originating as a black spot on the vine’s shoots, leaves, and berries. Although yield reductions can be disastrous if unchecked, the disease can be controlled through fungicide sprays.
Bunch Rot- Fungal Diseases
Bunch rot is a grouping of similar diseases caused by a number of fungi species. In general, bunch rots reduce crop yields and may adversely affect the character of the wine, imbuing it with moldy off-flavors. One of the most common forms of bunch rot is Botrytis bunch rot. Known in its malevolent form as grey rot, the Botrytis cinerea fungus will break down the skin of berries and allow other yeasts and bacteria to rot the grapes. It spreads quickly throughout vineyards. However, if the fungus invades healthy white grapes under favorable conditions, it will instead result in the noble rot, a precondition for some of the world’s greatest sweet wines. Botrytis bunch rot requires warm weather and humidity of at least 90% to germinate.
Pierce’s Disease- Bacterial Diseases
Caused by the bacterium Xylella fastidiosa and most commonly transmitted by the glassy-winged sharpshooter—a leafhopping insect found near citrus orchards and oleander plants—Pierce’s Disease is a scourge, rendering vines incapable of producing chlorophyll and killing it within one to five years. The disease is common in the southern United States and Mexico but is steadily moving northward in California, with sightings of the glassy-winged sharpshooter and outbreaks of the disease provoking major alarm in both Sonoma and Napa counties. There is neither a cure nor a chemical control for the disease, and authorities in other countries are maintaining strict quarantines to prevent its incursion.
Crown Gall (Black Knot)- Bacterial Diseases
The Agrobacterium tumefaciens bacterium causes the Crown Gall disease in a wide variety of plant species. When affected, a vine develops tumors (galls) on its trunk, which girdle and essentially strangle the vine, withering or killing outright the portions of the vine above. The bacteria thrive in colder climates, and systemically live inside the grapevine. During winter freezes, when the vine’s trunk may be ruptured, the bacteria invade the outer trunk, rapidly multiplying and fomenting the onset of disease. The disease is spread through the propagation of bacteria-infected budwood.
Bacterial Blight- Bacterial Diseases
Caused by the Xanthomonas ampelina bacterium, Bacterial Blight often kills young grapevine shoots. They develop dark brown streaks in early spring, and eventually wither and die. Spread by rain and compromised pruning tools, the disease can be controlled by hot water treatments and copper sprays, such as the Bordeaux Mixture.
Leafroll Virus- Viral Diseases
Leafroll Virus, a condition caused by a complex of at least nine different viruses, may be responsible for as much as 60% of the world’s grape production losses. Although affected vines display radiant shades of red and gold in the autumn, such beautiful colors, combined with a characteristic downward curling of the leaves, signal the virus’s malevolent side: reduced yields and delayed ripening. Leafroll Virus, spread through propagation of infected vines or by an insect vector like the mealy bug, is currently incurable but it will not kill the vine; thus, infected vines are not always removed.
Fan leaf Degeneration- Viral Diseases
Fanleaf Degeneration, a nepovirus spread by soil nematodes feeding on infected roots, severely curtails yields and affected vineyards must be removed. A complex of similar diseases, Fanleaf Degeneration deforms shoot growth, and leads to poor fruit set and shot (seedless) berries. The leaves on an infected vine are malformed, resembling fans in appearance, and may form yellow bands around the veins. The productive lifespan of the vine and its winter durability are diminished.
Flavescence Dorée- Phytoplasma Diseases
A form of grapevine yellows, Flavescence Dorée first appeared in Armagnac in 1949. Leafhopper insects and propagation of infected vines spread the disease, which will initially delay budbreak and slow shoot growth, eventually causing bunches to fall off the vine and berries to shrivel. The disease will discolor leaves, cause pustules and cracks to form, and may kill young vines. No cure exists, although insecticides may be used to control leafhopper insect populations and retard its spread.
What are the four primary soil types?
- Sandy Soils.
- Clay Based Soils
- Silt Soils
- Loam Soils
Sandy Soils
- Elegant wines, high aromatics, pale colour, low tannin
- Well drained and retain heat
- Warm Climates: softer wines, lighter acid and tannin
- Cooler Climate: Retain heat this helps in cooler climates
- A side benefit to sandy soils are their resistance to pests which could encourage more organic production in the wine region (i.e. Phylloxera)
Regions with Sandy soils…
- Cannubi, Barolo
- Northern Medoc- close to beach
- Graves in Bordeaux
- Lodi, USA
Clay Soils
- Muscular wines with high extract and colour
- They tend to stay cool and retain water
- Several types
- One type Calcareous Clay is said to be even cooler
- Clay produces some of the boldest red and white wines in the world.
Organic Viticulture
A system of grape-growing broadly defined as shunning man-made (industrially synthesized) compounds such as fertilizers, fungicides, herbicides, and pesticides, as well as anything that has been genetically modified. Organic viticulture is a prerequisite for the production of organic wine. It contrasts with ‘conventional’, sometimes even called ‘industrialized’ or ‘chemical’ viticulture, in two main ways: by stressing management techniques such as canopy management which seek to prevent rather than cure pests and diseases, and by using naturally occurring substances. The key organic management strategy for perennial crops such as vines, for which no crop rotation is possible, involves stimulating and maintaining healthy populations of a diverse range of soil microorganisms. The primary route to achieving this in organic vineyards is through the application of organic fertilizer in the form of compost. Unlike soluble fertilizer, this improves the structure and biological properties of the soil, rather than directly feeding the vine itself, and allows the slow release of mineral nutrients, by encouraging what in organic-speak is called a ‘soil food web’ of living organisms such as earthworms, beneficial bacteria, protozoa, and fungi (see soil biota). Man-made soluble fertilizers provide nutrients but do not promote the intrinsic life in the soil. The principle of feeding the soil and not the plant also means that foliar feed fertilizers—those applied to the leaves of the vine—are prohibited under organic norms. Growers who switch from conventional to organic soil and fertility management claim that vine shoots need much less frequent trimming as vine vigour is reduced. This makes yields less erratic (organic growers claim to get lower annual yields, but more regular yields overall compared with their conventional counterparts) and reduces the risk of attack by fungal diseases. However, the second and especially third years of the three-year conversion period from conventional to organic (or biodynamic) management are critical. This period can produce uneconomically low yields and unsustainably high disease pressure, two not unrelated conditions arising because vines have been unable to begin accessing slow-release nutrients from the soil, its reserves of quick-release soluble fertilizers having been all but exhausted by then. Therefore to make conversion to organics a success, would-be organic growers must adopt the prevention-rather-than-cure approach by putting in place the mechanisms first to create, and then to protect, both the soil humus and soil microbiology without which vines and soil nutrients will be unable to interact. This usually means a combination of compost and cover crops. Compost creates the preconditions for soil humification, being rich both in microbiology and in the basic building block of life, carbon (organic wine-growers aim for finished compost with a carbon-nitrogen or C/N ratio of 15:1). Cover crops then protect this microbiologically rich resource from soil erosion and nutrient leeching. Humus-rich, cover-cropped soils are more likely to hold vital water and nutrients than impoverished ones, and to promote the growth of mycorrhizal fungi on vine roots, organisms which allow vine roots to penetrate deeper into the soil and facilitate the uptake of micronutrients (see vine nutrition), both of which are said by some to make wines taste more terroir-specific and thus more complex. A small but increasing number of organic and biodynamic wine-growers (see biodynamic viticulture) have moved to minimal or no till systems by which inter-rows are almost permanently covered by perennial sward, arguing that the tidiness of a vineyard’s appearance has no direct bearing on wine quality. Such minimal cultivation preserves topsoil structure; it also means that the vineyard becomes a beneficial carbon-sink rather than the cause of the release of carbon and dust into the atmosphere, both of which may contribute to climate change and, in the case of dust, encourage certain vine mites. Perennial swards can also provide mulch to prevent weed growth directly under the vines if the inter-row vegetation is cut using the so-called mow and throw technique, leaving the mowings on the ground. For disease prevention, organic growers are reliant on naturally occurring substances. For instance, elemental sulfur and the salt copper sulfate (see bordeaux mixture) are used to control powdery mildew and downy mildew respectively. Both these treatments and others commonly used in organic vineyards (e.g. soap, plant oils and teas, seaweed, and powders based on bentonite, silicates, milk, and wild herbs) are contact or barrier sprays which, unlike chemically produced systemic sprays, do not enter either the vine’s sap or the grape pulp and so are less likely to produce residues in the wine. Organic growers, especially those in damp, humid climates, are often criticized for relying too heavily on copper-based treatments, leading to copper toxicity in the soil. Organic growers argue that copper residues are more easily mobilized where organic management fosters increased levels of soil microbiology, and that organic norms significantly restrict the amount of copper used compared with the amount allowed in conventional vineyards (to one-third in Europe, for example). Furthermore, these restrictions have either encouraged organic growers, especially those in marginal European climates, to switch from V. vinifera to disease-resistant interspecific crosses, or have inspired organic growers in both hemispheres to find genuinely sustainable alternatives to copper and sulfur for mildew control. The most notable of these is aerated compost tea, a low-tech, low-cost, rain-fast way of colonizing vines with beneficial aerobic bacteria, fungi, and other microorganisms that inhibit, consume, or outcompete disease-bearing pathogens. Another increasingly relevant example of this type of approach is the application of strains of the Trichoderma fungus to either vine trunks or pruning wounds to protect vines from esca. Other aspects of the organic prophylactic approach to farming in general, and to grey rot in particular, include employing canopy management techniques to open up the canopy and reduce the risk of rot. This can result in higher labour costs compared with those of conventional farming. Organic growers who pass these costs on in the price of the wine argue that from a holistic standpoint, organic viticulture eliminates costs to the wider community such as cleaning up by local authorities of groundwater polluted by anti-rot sprays—an increasingly sensitive issue. Organic growers also argue that this predisposition towards manual labour provides employment opportunities in communities suffering rural depopulation due in part to increased mechanization; and may account for why organic vineyards in France are now more likely than their non-organic counterparts to be picked by hand rather than by machine and to be estate-bottled.
Organic Viticulture- History
The origins of the organic agriculture movement are late-20th-century European. Like its predecessors the Enlightenment, the Romantic movement, and Darwinism, organics can be seen as attempting to redefine man’s relationship to his natural surroundings. By the end of the 1920s, when the green movement was closely intertwined with reactionary cultural and political phenomena such as National Socialism in Germany and Guild Socialism in Britain, organics had declared itself as opposing the industrialization of agriculture for both social and environmental reasons. Its main target was the mineral ‘NPK’ fertilizer devised in 1836 by Justus von Liebig and mass produced from 1913 using the Haber-Bosch process. These fertilizers transformed the agricultural landscape and economic and social structures. However, two World Wars, austerity, rural depopulation, rapidly rising metropolitan populations, and the ease with which nitrogen production was switched post-1945 from making munitions to fertilizer meant the infant organic movement provided only a fringe argument against the inexorable industrialization of agriculture. And whereas industrial food conglomerates found globalization both necessary and desirable, organic activists struggled to form international bonds, and hence risked accusations of parochialism. The formation in 1972 of the International Federation of Organic Agriculture Movements (IFOAM) to oversee the setting of the majority of the world’s organic standards and the certification bodies has helped change this perception. Nevertheless, although the first organic vineyards were established after the Second World War, it took until the late 1980s for wines produced from organically grown grapes to begin to shake off a reputation for earnest amateurism, inconsistency, and poor value. Critics argue that organic wine’s now steadily increasing market share, which began to grow in Europe in the early 1990s, was mainly due to eu subsidies, initially to help growers survive the three-year organic conversion process, but now provided to stimulate rural development and optimize the vineyard ecosystem. However, its advocates see the main selling point for organics in wine as reinforcing the key notion of terroir. This ‘working with rather than against nature’ handily chimed with increased public unease at the effects of industrialized farming on our food rather than in our wine, notably in the UK, where the food scandals of the mid-1990s and early 2000s involving BSE and foot-and-mouth disease provoked widespread public debate. Concern about the perceived threat that genetic modification might have on food and wine also stimulated greater interest in the alternatives. More particularly, though, growers themselves began adopting organics in greater numbers because they felt it would preserve and enhance their main equity, terroir, while giving the wines an organoleptic and marketing edge. More effective vineyard machinery for the control of weeds and disease, improved communication regarding which organic techniques work best, and consumer demand have also contributed to the steady growth in organic viticulture worldwide.
Organic Viticulture- Organic Certification and Terminology
To be described as ‘organic’, a vineyard and/or its wine (see organic wine) must have third-party certification, usually from a non-governmental organization or ‘certifier’ accredited by a ministry of agriculture or its equivalent and to criteria which are ISO 17065 (formerly ISO65) compliant. This verifies that the certifier’s standards conform to organic global baselines set by IFOAM (see above). Organic certification is granted after a three-year conversion period as wine grapes are a perennial crop (conversion takes two years for annuals such as cereals or carrots). Certification aims to protect both bona fide organic producers and consumers of organic products from anti-competitive activity or fraudulent claims. Certifiers can advise vineyard owners as to why their vineyard does not meet their standards, but cannot provide advice on which organic sprays might be best in any particular situation. Agreements in 2012 between the US, Canada, and the EU mean that organic production and labelling finally enjoy a strong degree of transnational if not yet global equivalence (previously an organic French vineyard exporting to the US needed both EU and American certification documents). Winegrowers who impose on themselves stricter standards than those of the organic baseline may join private organic associations such as France’s Nature et Progrès or Germany’s Ecovin. These bodies require, for example, wider buffer zones between conventional and organic plots, allow fewer fining agents, and require lower levels of free and total sulfur dioxide than those permitted for organic wine.
Organic Viticulture- Worldwide
In 1999, 0.5–0.75% of the world vineyard was certified organic or biodynamic or in conversion, the majority of which comprised small, heritage organic estates prioritizing local rather than international markets. As more blue-chip estates in France, notably in the Loire, Alsace, and Burgundy, began converting to organics and biodynamics in the 1990s, conventional wine’s potentially negative impact locally and on the wider environment started to be questioned. In California, Jimmy Fetzer’s creation of a Mediterranean-style vine garden melding biodynamic wine-growing with vegetables, olives, fruit, and both fluffy and feathered livestock, helped redefine organic wine as a colourfully positive lifestyle choice, finally providing the movement with sex appeal to go with its gravitas. By the end of the 2000s, Mediterranean France’s Languedoc, Roussillon, Rhône, and Provence vineyards had become the global organic hotbeds, helped by a beneficial climate and a slew of second-careerists snapping up competitively-priced de facto organic old-vine vineyards, often from retiring or bankrupt co-operative growers. France’s certified organic vineyard tripled in size between 2007 and 2011, and organic viticulture’s share of the global vineyard went from under 2% in 2007 to an estimated 4.3% in 2013. Europe has 90% of the global organic vineyard, with Spain, France, and Italy together having 75% of the global organic vineyard. Austria’s position as the world’s wine-growing nation with the highest proportion of organic vineyards is partly due to its pre-emptive investment in educating potential consumers about organics, thereby creating a ready market for organic food and wine. Percentages of certified organic and biodynamic vines as part of the national/regional vineyard are as follows: France (8.8% in 2014; 2% in 2005; 0.5% in 1995), Italy (>11% in 2013; 6.5% in 2010; 4.4% in 2000), Spain (8.4% in 2014;
Hail
Frozen raindrops or ice bodies built up by accretion, typically falling in thunderstorms. To the normal ill effects of heavy summer rainfall is added direct physical damage to the vines and fruit. That to the vines ranges from ripping and stripping of the leaves to bruising and breaking of the young stems: effects which can carry over to the following season or even much longer. Damage to young bunches may destroy or at best reduce the crop, although compensatory growth of the remaining berries may minimize the effects on final yield. Hail damage while berries are ripening, on the other hand, is invariably a disaster. Smashed berries are prey to rot and ferment on the vine, rendering even undamaged parts of the bunches unusable. burgundy is particularly and apparently increasingly prone to hail damage, as is Mendoza in argentina. Hail is said to cost French agriculture more than half a billion euros a year. Hailstorms characteristically follow irregular but well-defined pathways through an area, sometimes devastating parts of a vineyard but leaving other parts untouched. Local topography may result in a tendency for the storms to follow preferred pathways, but largely their incidence is unpredictable. Various prevention techniques have been tried, including seeding the clouds with silver iodide or dry ice, from planes or cannon, to reduce the size of the hailstones so that some melt before they reach the ground, and using hail cannon that generate shock waves intended to disrupt the formation of hail. Covering the vines with netting is another laborious and expensive option which reduces the impact of hailstones but also reduces the amount of sunlight reaching the vines—desirable only in the hottest wine regions. The technologies can hardly be described as proven, but have found supporters among vine-growers understandably desperate to protect their hard-won crops. Insurance against hail is rarely cost-effective.
