D1: Viticulture - from PS Hill Flashcards
1
Q
What are the key vine species, their origin and their primary use?
A
Eurasian, predominantly for grape production:
- Vitis vinifera
North America varieties, predominantly for rootstock:
- Vitis labrusca
- Vitis riparia
- Vitis berlandieri
- Vitis rupestris
2
Q
Name the main structural groups in a vine
A
4 main groups:
- main shoots/stems
- one year old wood
- permanent wood
- roots
3
Q
Name the main structure of vine shoots
A
- stem with nodes
- buds
- leaves
- tendrils
- lateral shoots
- leaves
- inflorescences/grape bunches
4
Q
List the primary purposes of the stem
A
- primary support structure
- transport of water and solutes
- carbohydrate store
5
Q
Lignifying is the process by which _____ become _____
A
Lignifying is the process by which SHOOTS become CANES
NB, lignifying turns wood from green to brown
6
Q
______ is the process by which shoots become canes
A
LIGNIFYING is the process by which shoots become canes
NB, lignifying turns wood from green to brown
7
Q
What are the types of buds?
A
Compound buds (or latent buds) form in one season and break open the next. They are supported by secondary and tertiary buds in case of frost/damage
Prompt buds form and break open in the same season and produce lateral shoots
8
Q
What are lateral shoots?
What is the impact of lateral shoots?
Name a grape variety which typically has them?
How are they typically managed?
A
Lateral shoots are from buds that formed that season.
They can give rise to too much shade/vegetation, and potentially a secondary crop with later ripening.
Pinot Noir
They are often summer pruned to focus ripening on primary shoot structures
9
Q
_____ is a cluster of flowers that becomes grapes during the process of ________
A
An INFLORESCENCE is a cluster of flowers that becomes grapes during the process of FRUIT SET
10
Q
Name the key parts of a grape and the attributes they can bring to wine
A
Pulp - bulk of the juice (water, sugar), some aroma compounds and aroma precursors
Seed - tannins
Skin - aroma compounds, aroma precursors, tannins, colour
Bloom - naturally occurring yeasts
Stem - tannin
11
Q
What structures are one year old wood pruned into?
A
cane: 8-20 buds
spur: 2-3 buds
12
Q
What structures can permanent wood be shaped into?
A
Trunk - vertical
Cordons - horizontal
13
Q
What are the key attributes of roots?
A
- Anchor vine
- uptake of water and nutrients
- hormone production
14
Q
What are main methods of vine selection and propagation within a single variety?
A
Layering - no selection, adjacent vines are used to plug gaps in vineyard
Clonal selection - typically cutting
Mass selection- typically cutting
15
Q
What are the main methods of selection and propagation of new grape varieties? Give an example of each
A
Cross fertilisation - pollen from one vine is transferred to stamen of a different vine.
e.g. Pinotage from Pinot Noir and Cinsault
Cab. Sav. from Sauvignon Blanc and Cab. Franc
Müller-Thurgau from Riesling and Madeleine Royale
Hybridisation - pollen from one species is transferred to stamen of a different species. e.g. Vidal Blanc from Ugni Blanc (vinifera) and Seibel
16
Q
List the phases of vine growth, starting in winter
A
- Dormancy
- Budburst
- Shoot and leaf growth
- Flowering and fruit set (8 weeks after budburst)
- Grape Development
- Harvest
7/1. Leaf fall/ dormancy
17
Q
What resources does a vine need to survive?
A
- Water
- Sunlight
- Warmth
- Nutrients
- Carbon Dioxide (rarely a factor for growers)
18
Q
What average temperature gives rise to dormancy?
A
<10°C
19
Q
What temperature kills most vines?
A
Vitis vinifera is killed below -25°C
20
Q
What average temperature gives rise to new growth in the spring?
A
Budburst is triggered >10°C
21
Q
Compare the impact of a continental climate over maritime on budburst
A
Sharper changes in temperature in continental systems, typically give rise to uniform budburst and ultimately ripening. There is a lower risk of frost damage from a cold spell after budburst
22
Q
Compare the impact of soil water retention on temperature and vine growth
A
Free draining soils hold less water, and heat up quicker encouraging earlier ripening
23
Q
How and why do growers delay budburst?
A
Late winter pruning can delay budburst, to help avoid spring frost damage
24
Q
What does a vine need during its ‘shoot and leaf growth’ phase?
A
You do not want early growth limited. Ensure leaves form to photosynthesise. You can always prune leaves, you can’t add them!
Warmth - temp >10°C
Access to carbohydrates - e.g. late winter pruning can reduce these and slow growth. Large harvest in the prior year can reduce storage
Access to nutrients and water
25
What does a vine need to maximise flowering and fruit set?
Warm temperatures in the previous year result in a high inflorescence count in compound buds
Current year needs a minimum temperature of 17°C, and optimal germination is over 25°C, with dry, calm days so that pollen is not washed away from the stigma, and can grow fertilisation tubes
26
Name and describe the process by which grapes form from flowers?
Fruit set
Pollen grains land on the stigma and from there grow a tube into the ovary to deliver sperm cells that fertilise the vines eggs. Fertilised eggs form seeds with grapes, and the walls of the ovary enlarge to form the pulp and the skin.
27
______ is a condition in which fruit set has failed for a high proportion of flowers.
Describe its causes and name a susceptible variety
COULURE is a condition in which fruit set has failed for a high proportion of flowers
It is cause by vine stress (lack of water, or too cold), or too vigorous vegetative growth competing for resources (too much fertiliser)
Grenache, Cabernet Sauvignon, Merlot, Malbec
28
What is coulure?
A high failure rate for fruit set
29
______ is a condition in which there is a high proportion of seedless grapes.
Describe its causes and name a susceptible variety
MILLERANDAGE is a condition in which there is a high proportion of seedless grapes.
It is caused by cold, wet weather at pollination and fruit set disrupting the growth of pollen tubes.
Chardonnay, Merlot
30
What is millerandage?
Millerandage is a term for a high proportion of seedless, smaller grapes.
31
What are the key stages of grape development?
1. Berry formation
2. Veraison
3. Ripening
4. Extra-ripening
32
What compounds accumulate during initial berry formation?
```
Tartaric acid
Malic Acid
Aroma compounds/ precursors
Methoxypyrazines (herbaceous flavours)
Bitter tannins
```
33
What are methoxypyrazines?
Herbaceous flavoured compounds formed in some grape varieties. The levels usually drop in ripening (Cabernet Franc and Gamay both lose vegetal flavours when ripe)
34
What are anthocyanins?
Compounds that give black grapes their colour
35
What compounds give black grapes their colour?
Anthocyanins
36
What compound levels change during berry ripening?
- Malic acid levels may drop as plants use it as an energy source as sugar is diverted to grapes
- Anthocyanins accumulate in black grapes
- Sugar accumulates
- Water accumulates, diluting acid
- Methoxypyrazine levels fall
- tannins can polymerase and reduce bitterness
37
What are terpenes?
Terpenes are aroma compound that gives floral and citrus aromas. e.g. the grapey aroma in Muscat
38
What is a good temperature range for ripening and why?
15°C to 21°C (depends on variety)
Too low and malic acid levels remain high; methoxypyrazine levels remain high. Grapes will be more herbacious and acidic
Too high and lots of acid is lost. Grapes ripen too quickly and do not develop as many aroma compounds. Grapes will be sweeter and blander
39
What happens during extra-ripening of grapes?
Grapes lose water and shrivel. Ripe aromas can develop (potentially good or bad depending on the variety and style of wine)
40
How can growers maximise latitude at or above 50°?
At high latitude, plant vines at a lower altitude, and aspect towards the sun to maximise sun exposure.
Proximity to water can dampen temperature swings, protecting from frost in winter, e.g. finger lakes
Use early ripening grapes - e.g. Chardonnay and Pinot Noir
Free draining soils warm up more quickly and promote early budburst to maximise the growing season
41
How can growers minimise latitude at or below 30°?
Steep slopes may have reduced water and soil quality, slowing growth in warmer climates
Plant at high altitude, and/or on a slope away from the sun (e.g. south facing in southern hemisphere). Each 100m of altitude, drops average temperate by 0.6°C
Proximity to water can dampen temperature swings - limiting overheating in summer
Use late ripening grapes in warmer climates (e.g. Cabernet Sauvignon)
Clay rich soils hold water and delay budburst as they remain cool
42
What is the minimum annual rainfall for a vine? Give examples of how soil type can increase/decrease these minimums in Hawkes Bay and Jerez respectively
500mm in cool climates, 750mm in warm
However, Hawkes bay has to irrigate despite receiving 800mm due to highly drained soil. Jerez copes on 650mm due to albariza, a clay soil with excellent water retention
43
Which wine growing areas are particularly reliant on irrigation?
Argentina, California, South Africa and Australia
44
What are optimum rain levels at key points during the season for grape development?
High rain in early spring to encourage early vegetative growth
Reduced water in late spring and early summer to allow germination and fruit set, and limit competition for carbohydrates as vegetative growth is reduced
Limited rainfall in late ripening to stop dilution and splitting
45
What are the top 5 vine nutrients and their purpose?
1. Nitrogen is required to form proteins and chlorophyll
2. Potassium - regulates water
3. Phosphorus - used in photosynthesis
4. Calcium - used in cell structure and photosynthesis.
5. Magnesium - in cholorphyll
46
What is the impact of too much/ little nitrogen?
High levels result in too much vigour - secondary impacts of shading grapes and hindered fruit set and ripening, and encourage fungal disease.
Low levels cause leaf yellowing and reduced vigour. Yeast may be impacted during fermentation.
47
What is the impact of too much/ little potassium?
High levels - can impact magnesium uptake, reducing yields. It may raise also raise the pH in the grape/must as potassium accumulates
Low levels impact sugar accumulation and limit growth
48
What is the impact of too much/ little phosphorus?
High levels are not common
Low levels detrimentally impact root systems, impacting water and nutrient uptake.
49
_____ is the yellowing of vines in high pH soils (e.g. ____ or ____ soils) that limit uptake of ______
CHLOROSIS is the yellowing of vines in high pH soils (e.g. CHALKY or LIMESTONE soils) that limit uptake of IRON
This is common in CHALKY soil
50
What are the minerals particle types that can make up soil?
Sand (large), silt (medium), clay (fine)
51
_____ describes a soil with moderate proportions of _____, ______ and ______
LOAM describes a soil with moderate proportions of SAND, SILT and CLAY
52
What does GDD stand for? How is it determined?
Growing degree days
Average temperature in excess of 10°C in a given month
x
No. of days in month
Calculated for each month in a season
53
Name at least three climate classifications
- Growing Degree Days
- Huglin index (widely used in Europe)
- Mean temperature of warmest month (MJT - used in hot climates where the stress of the warmest month is important)
- Growing Season Temperature (GST)
- Köppens classification (maritime, Mediterranean, continental)
54
What GST bands are used by WSET to categorise climates?
Cool <16.5°C
Moderate 16.5°C - 18.5°C
Warm - 18.5°C - 21°C
Hot >21°C
55
What are the negative implications of climate change on vines and ultimately wine?
Careful - very area specific!
Earlier ripening reduces the accumulation of aromas and tannins
Higher sugar levels increase alcohol
Reduced malic acid increases pH
Specific flavour profiles may change (e.g. black pepper in Syrah may not develop)
Increased water stress
Erratic weather events can reduce yields (e.g. storms, hail)
56
What are the positive implications of climate change on vines and ultimately wine?
Careful - very area specific!
Opens up new areas for cultivation
Reduced impact of fungal diseases
57
List key advantages and disadvantages of monoculture crops
Advantages:
- increased mechanisation
- reduced competition for resources
- ability to tailor husbandry to specific varietal requirements (e.g. irrigation)
Disadvantages:
- crop is more prone to disease
- depletion of nutrients
- reliance on chemicals can increase environmental damage
58
List key advantages and disadvantages of sustainable agriculture
Advantages:
- more thoughtful approach leads to potentially better outcomes through a wider consideration of viticulture impact
- reduced interventions (spraying, poisons)
- cost savings
Disadvantages:
- no clear global definition, national standards are typically set
- standards can be set too low nationally
59
List key advantages and disadvantages of organic viticulture
Advantages:
- healthier balanced soil
- reduced chemical treatments
- saving cost of synthetic chemicals
Disadvantages:
- potential yield reduction
- more volatile yields, especially in bad years
- reliance on copper sprays
- increase in cost and time
60
What are the key features of organic viticulture?
- compost provides nutrients
- cover crops reduce erosion and provide green manure
- uses natural fertilisers
- reduced monoculture - plant hedges, etc
61
What are the key features of biodynamic viticulture?
- align activities with philosophical and cosmological concepts. e.g. take grafts when the moon in ascending
- use of homeopathic remedies and certain preparations to fertilise soil and treat pests, e.g. preparation 500 is manure based, 501 is silica based
62
Who developed the concept of biodynamic viticulture?
Rudolf Steiner and Maria Thun
63
What are the key features of precision viticulture?
- use detailed data to vary interventions/husbandry by plot and row
- data may include soil composition or growth rates
- interventions that can be tailored include: choice of rootstock/grape, canopy management, irrigation, harvest timing
64
List key advantages and disadvantages of precision viticulture
advantages:
- maximise understanding of yields and/or grape quality
Disadvantage:
- cost of data collection, training and analysis
65
What attributes might you look for in selecting a site for high volume wine?
- flat for mechanisation
- consistent weather for predictable yields and quality
- source of water
- warm conditions to reduce fungal diseases
- price of the land
- proximity of labour/transport/winery
66
What attributes might you look for in selecting a site for premium wine, in a cool climate?
Focus on quality grape production. e.g. aspect/altitude that maximises ripening potential
Understanding whether the quality of grapes and wine that can be produced will support a profitable business
67
List at least 5 ways you might prepare soil for planting in a new site
- remove large rocks
- subsoiling to remove impervious plough pan layers
- remove old roots
- use of systemic herbicides
- application of manure/compost
- pH adjusting (e.g. add lime)
- landscaping - e.g. terracing
68
List at least 5 ways grape varieties can be selected to match the climate
- budding timing: early to maximise growing season (Chardonnay), late to avoid frost (Riesling)
- Annual life-cycle: early ripening for cool climates (Chardonnay, Pinot Noir), late for warm (Mourvedre)
- Drought tolerance: Grenache
- Disease resistance: Cabernet Sauvignon is less susceptible to grey rot
- Winter hardiness: Vidal, Riesling and Cabernet Franc are tolerant of cold
- Vigour: high vigour varieties (Sauv. Blanc) can be planted in less fertile areas, or additional canopy management is required
69
List at least 5 non-climatic factors that influence the choice of grape to plant
- style of wine, e.g. tannic wine needs tannic grape
- yield: high yield for mass production. e.g. Grenache
- Management cost: e.g. Pinot Noir needs more attention due to disease susceptibility
- Law: choice may be restricted
- availability of cuttings
- Market demand
70
What rootstock is tolerant of phylloxera?
All main North American varieties
71
What rootstock is tolerant of root-knot nematodes?
Ramsey or Dog Ridge (both Vitis Champini)
72
What rootstock is tolerant of drought?
110R or 140R. Both hybrids of V. rupestris and V. berlandieri
73
What rootstock is tolerant of acidic soil?
99R or 110R. . Both hybrids of V. rupestris and V. berlandieri
74
Name a low vigour rootstock, and where/why it is helpful?
420A or 3309C - can advance ripening in cool climates
75
Name a high vigour rootstock, and where/why it is helpful?
140R can boost growth in infertile soils
76
How many years before a vine produces suitable grapes?
PDO wines in the EU are 4 years by law
2-3 years if not required by law
77
How many years until a vine stops producing suitable grapes?
10-40 years for maximum yields
Vines over 50 years are typically only retained for making premium wines due to low yields
78
What factors make up soil health?
structure (sand/silt/clay mix) - drainage/water holding capacity, ability for roots to penetrate
organic matter - hummus
living organisms - these break down organic matter into inorganic
nutrients
79
What are the two categories of fertilisers?
Organic (e.g. compost)
Inorganic - manufactured
80
What are organic fertilisers and how do they get into a plant?
Fresh or composted plant or animal waste, that is broken down by organisms in the soil to release inorganic nutrients for uptake by roots
81
What are mineral fertilisers?
inorganic nutrients that can be taken up directly by vines
82
______ is a method of weed control that ploughs weed roots back into the soil
Cultivation
83
What are the advantages/ disadvantages of cultivation?
Advantages:
- chemical free (organic and biodynamic friendly)
- fertilises soil
Disadvantages:
- changes the soil structure
- buries seeds so weeds can grow back
- requires heavy machinery
- can increase vigour if all competition is removed
84
What are the main types of herbicide?
Pre-emergence: persist in soil
Contact: sprayed on established weeks and kill parts they make contact with
Systemic: taken up by plants and kills the whole plant
85
What are the advantages/ disadvantages of herbicide?
Advantages:
- cheap labour and machinery
- effective
- don't damage soil structure
Disadvantages:
- environmental/ operator/ consumer risk
- resistance can arise
- increase vigour too much if all competition is eliminated
- not allowed in organic/biodynamic
86
What are the advantages/ disadvantages of cover crops?
Advantages:
- organic/biodynamic suitable
- manage vine vigour by competing for water/nutrients
- surface for machinery
Disadvantages:
- risk of too much competition
- hard to mow
- can be slippery on slopes when wet
87
What are the advantages/ disadvantages of mulching?
Advantages:
- organic/biodynamic suitable
- reduces water evaporation in hot climates
- long term release of nutrients
Disadvantages:
- bulky to transport
- needs a lot to be effective
- can increase vigour too much
88
How can a vineyard reduce water usage?
- efficient drip system
- drought tolerant varieties, e.g. Grenache
- drought tolerant rootstock, e.g. 140R
- mulch cover
- increase water retention with additional humus
- promote deep root growth
89
What types of irrigation are there?
Drip
Flood
Channel
Sprinkler
90
What are the advantages of drip irrigation?
- efficient
- highly tailored
- can supply liquid fertiliser
- used on any terrain
91
What are the disadvantages of drip irrigation?
- high capital cost
- needs clean water to keep holes clear
- need maintenance to keep clear
- unlike sprinklers, cannot protect against frost
92
How is water managed across the growing season?
Lots of water at budburst to encourage initial leaf growth
Water deficit may benefit veraison
Careful management at other times
Might want reduced water at harvest time to prevent swelling
93
What are the aims of canopy management?
- Effective light absorption by canopy
- Reduce shade on grapes
- Uniform microclimates for grapes
- Balance between vegetative and reproductive functions in the vine
- Ease of harvesting
- Promote air circulation
94
What impact does sunlight have on different compounds in a ripening grape?
- increases sugar through photosynthesis
- increases tannins
- increases polymerisation of tannins
- decreases malic acid
- increases some aroma compounds
- decreases methoxypyrazines
95
What happens if a grape gets sunburn?
Too high temperatures damage grapes causing browning
96
What are the implications on the following season from a too low yield in a year?
The following year can be too vigorous, reducing bud fruitfulness and encouraging vigorous growth
97
What are the implications on the following season from a too high yield in a year?
Trunks and roots can be exhausted of carbohydrate, weakening vine growth the following year
98
What is a high planting density and a low planting density?
low - 100s of vines per hectare
high - 10,000 vines per hectare
99
How is vine density determined when planting?
Vigour of the variety: low vigour can be more closely planted that high vigour
Trellising techniques
Local laws may put limits in place
100
What is considered when choosing a canopy training method?
- Vine vigour
- Site topography
- Mechanisation requirements
101
What is vine training?
Shaping of permanent wood
102
What are the common types of vine training?
Head training - just a trunk
Cordon training - arms on a trunk
```
Both can be high (avoid frost, easier harvesting)
or low (benefit from heat retained by soil)
```
103
What are the common types of pruning?
Spur pruning - 2-3 buds
Replacement cane pruning 8-20 buds
104
Why are some vineyards untrellised?
Called bush vines - simple and inexpensive. Normally practiced in sunny regions to keep grapes shaded, and in dry regions as vigour is limited (other too much canopy grows)
105
What is the most common trellising system?
VSP: Vertical Shoot Positioning - best for low/moderate vigour
106
What trellising is used for vigorous vines?
GDC - Geneva Double Curtain
Lyre
Scott-Henry
107
What is the Scott-Henry technique?
Double level VSP (vertical shoot positioning) for high vigour vines
108
What is GDC?
The Geneva Double Curtain training, splits the canopy horizontally
109
List at least 5 summer pruning techniques
Disbudding
Shoot removal
Pinching, during fruit set
Leaf removal
Crop thinning/green harvesting
110
Why carry out summer pruning?
Reduce competition between vegetation and grapes
Increase sun/circulation for grapes
Remove grapes ripening out of sync
111
What are the physiological changes in a vine during water stress?
Leaf stomata close to reduce transpiration and limit water loss, which also reduces gas exchange.
Photosynthesis is reduced as CO2 levels fall.
Vegetation growth and grape ripening reduce.
Prolonged periods result in leaf loss and death of the vine.
112
How can water stress be managed?
Irrigation systems, where laws allow
Drought resistant rootstock (e.g. 110R and 140R)
Drought tolerant grape variety (e.g. Garnacha/Grenache)
113
What does an excess of water cause?
Vegetative growth results in shaded grapes, reducing ripeness.
Increased risk of fungal disease.
Waterlogged roots can impact growth and kill the vine, and lead to compacted soil
114
How can an excess of water be managed?
Primarily in vineyard selection and design: plant on slopes; plant in free draining soil; construct drainage systems
115
What are the two worst times in the season for heavy rain?
During pollination and fruit set - it can result in millerandage and coulure
At harvest grapes can swell and split - diluting must, and potentially causing grey rot and oxidation
116
How can heavy rain at harvest be managed?
Trade off from bringing the harvest forward, or risking damage to the crop from rain.
117
What climate types and/or geographical locations are most at risk from vine death in freezing temperatures?
Strong continental climates: e.g. Canada, Washington State, parts of China
118
How can vine death from freezing be managed?
Hillside planting over valley floors
Plant near bodies of water to benefit from temperature moderation
'Hilling up' soil around the vine graft
Burying the vine over winter
Prune multiple trunks to increase chances of survival
119
When is frost the biggest risk to a vine?
During budburst, frost can kill the buds and young shoots, leaving growers reliant on secondary buds. These have lower yields and delayed ripening.
120
How can frost risk be minimised?
Avoid planting in frost pockets
Late winter pruning can delay budburst
Plant late budding varieties (e.g. Reisling)
Train vines high
Bare soil between vines absorbs more heat in daytime to reflect back overnight
121
When frost is imminent, how can the risk be minimised?
Water sprinklers can release latent heat in water, but must be kept on until temperatures rise. There is a risk of sunburn through the ice on a clear day.
Wind machines / helicopters - work if there is an inversion layer. This is typically radiation frost
Burners (smudge pots) - although these are polluting
122
How can the risk of hail be minimised?
Mainly netting, although this can shade grapes
Multiple plots spreads risk - hail is often localised
123
How can the risk of fire be minimised?
Have water on site, use sprinklers. Have fire breaks in crops. Depends on the size of the fire!
124
What can be done about smoke taint?
Smoke taint is thought to be concentrated in the skin:
- Minimise skin impact in fermentation
- Whole bunch pressing
- Lower fermentation temperature
- Reduce maceration
125
What animal pests can attack vines and what is the primary defence against each?
Phylloxera - resistant rootstock
Nematodes - resistant rootstock
Grape moths - chemicals (insecticide, or pheromones)
Spider mites - pesticides
Birds - netting
Mammals - fencing
126
List at least 4 fungal diseases
Powdery mildew
Downy mildew
Grey rot
Eutypa Dieback
Phomopsis
ESCA
127
What diseases are the most prevalent vine diseases, which attack young, green parts of the vine
Powdery mildew and downy mildew
128
How can powdery mildew be treated?
Prune an open canopy to minimise shade
Early spraying of sulphur
Systemic fungicides
129
How can downy mildew be treated?
Bordeaux mixture - copper sulphate and lime
130
What fungus attacks fruit and which species are particularly vulnerable?
Grey rot
Species with tight bunches or thin skins: Semillon, Sauvignon Blanc, Pinot Noir
131
How can grey rot be treated?
Prune an open canopy
Fungicides
Competing bacteria (Bacillus subtilise)
132
________ infects pruning wounds and results in rotten wood
Eutypa dieback (also called Dead arm)
133
How can eutypa dieback be treated?
Prune late and apply fungicide to wounds
Cut back dead wood 5cm past infection. Burn the wood
Cut away plant and regrow from a sucker
134
What are the 2 main vine bacterial diseases?
Pierce's disease
Grapevine yellows
135
How are bacterial infections spread?
They need a vector
Pierce's disease is the sharpshooter
Grapevine yellows is the leafhopper
136
What are the 2 main vine viruses?
Leafroll virus
Fanleaf virus
137
How are viral infections spread?
Either with a vector, or grafting infected material
Fanleaf vector is the dagger nematode
Leafroll vector is the mealy bug
138
_____ causes vines to grow twisted and stunted
FANLEAF VIRUS causes vines to grow twisted and stunted
139
How would you identify leafroll virus in a vineyard?
Slow growth, yields halved and leaves change colour in the autumn (red or yellow)
140
How would you identify fanleaf virus in a vineyard?
Stunted, twisted vines
141
What factors influence harvest timing?
Climate
Sugar levels - minimum alcohol levels may need to be reached
Forecast rain
Aroma and tannin ripeness (usually determined by taste)
Wine style - e.g. later for botrytis, or off dry styles.
142
What is the typical sugar level in a grape harvested for still wine?
19° and 25° Brix, which will convert into 11–15% abv wine
143
What supplementary processes can increase the quality of grapes when machine harvesting is used?
Hand selecting undesirable fruit before harvesting
Use a bow-rod machine
Use an optical sorting machine
Sort on arrival
144
What are the advantages of machine harvesting?
Faster and cheaper
Consistent availability
Harvesting at night is an option
Can be more flexibly on harvest dates
145
What are the disadvantages of machine harvesting?
May rupture grapes
Only supported by large crops - major investment
Needs mono crop
Needs flat slope
146
What are the advantages of hand harvesting?
Highly selective grape selection
Flexible for topography
Grapes can be harvested whole, or in whole bunches
147
What are the disadvantages of hand harvesting?
Cost
Need a work force
Have to harvest during the day
148
Which wines require grapes to be hand harvested?
Whole-bunch pressed wines: e.g. bottle fermented sparkling wines
Carbonic or semi-carbonic wines: e.g. Beaujolais
Botrytis affected grapes
149
Set out the typical viticulture requirements for the best Priorat vineyards
Hot enough to plant on north facing slopes to avoid sun
Free draining soils, and no permitted irrigation, limits vine vigour. So vines can be bush trained for shade.
Low density planting to avoid competition for water and nutrients (up to ~3,000 vines per hectare)
Garnacha and Carieñena are drought resistant and late ripening
Drought tolerant rootstock may be used (e.g. 140R)
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Set out the typical viticulture requirements for the best Pauillac vineyards
Variable maritime climates - so different grapes are planted that can be blended, as these spread risk of a deep crop loss.
Poor, free draining soils limit vigour, so planting using VSP as simple and maximises grape exposure to the sun.
Rain and mist risk means canopies are pruned clear of grapes, which increases sun for ripening and reduces fungal disease
Vines are planted at high densities to maximise yield as land is so expensive
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Set out the typical viticulture requirements for the best Finger Lake vineyards
Despite the proximity of water, climates are cool, so Reisling is common as it is late budding to protect against frost, and is winter hardy
Growers may hill up the soil in winter
Soils are nutrient rich and rain is plentiful. Scott-Henry trellising improves light interception, gives circulation to protect against fungal disease, and makes the most of the large vine
Summer pruning can help ripening
Vine densities are low to give vigorous vines space. Wide spacing for mechanical harvesting
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Set out the typical viticulture requirements for Californian Central Valley vineyards to produce high-volume wine?
The climate is warm, and irrigation permitted, so vines grow vigorously. Low density planting reduces upfront costs of vines (1,500 vines per hectare) and vines grow quite large
Varieties are high-yielding
Spur pruning is quicker and lower skilled, reducing cost
Shoots are hung over a single wine to reduce trellis cost, and provide shade from intense sun
Machine harvesting reduces cost and enables night time harvesting to save on refrigeration
Early harvest avoids spoilage risk and reduces rot
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What can calcium deficiency cause?
Detrimental impact on fruit set
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What can magnesium deficiency cause?
Impact chlorophyll reducing photosynthesis. Reduced grape yields and poor ripening
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Why is a large, well-developed root system beneficial to viticulture?
If a root system is large in comparison to the canopy, the more it puts a stress on the vine and produces higher quality grapes.
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Compare a Mediterranean climate to a maritime climate
A Mediterranean climate is warmer, with an extended autumn. It is more suited to late budding, late ripening varieties like Mourvèdre
