D1: Viticulture - from PS Hill Flashcards
What are the key vine species, their origin and their primary use?
Eurasian, predominantly for grape production:
- Vitis vinifera
North America varieties, predominantly for rootstock:
- Vitis labrusca
- Vitis riparia
- Vitis berlandieri
- Vitis rupestris
Name the main structural groups in a vine
4 main groups:
- main shoots/stems
- one year old wood
- permanent wood
- roots
Name the main structure of vine shoots
- stem with nodes
- buds
- leaves
- tendrils
- lateral shoots
- leaves
- inflorescences/grape bunches
List the primary purposes of the stem
- primary support structure
- transport of water and solutes
- carbohydrate store
Lignifying is the process by which _____ become _____
Lignifying is the process by which SHOOTS become CANES
NB, lignifying turns wood from green to brown
______ is the process by which shoots become canes
LIGNIFYING is the process by which shoots become canes
NB, lignifying turns wood from green to brown
What are the types of buds?
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
What are lateral shoots?
What is the impact of lateral shoots?
Name a grape variety which typically has them?
How are they typically managed?
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
_____ is a cluster of flowers that becomes grapes during the process of ________
An INFLORESCENCE is a cluster of flowers that becomes grapes during the process of FRUIT SET
Name the key parts of a grape and the attributes they can bring to wine
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
What structures are one year old wood pruned into?
cane: 8-20 buds
spur: 2-3 buds
What structures can permanent wood be shaped into?
Trunk - vertical
Cordons - horizontal
What are the key attributes of roots?
- Anchor vine
- uptake of water and nutrients
- hormone production
What are main methods of vine selection and propagation within a single variety?
Layering - no selection, adjacent vines are used to plug gaps in vineyard
Clonal selection - typically cutting
Mass selection- typically cutting
What are the main methods of selection and propagation of new grape varieties? Give an example of each
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
List the phases of vine growth, starting in winter
- Dormancy
- Budburst
- Shoot and leaf growth
- Flowering and fruit set (8 weeks after budburst)
- Grape Development
- Harvest
7/1. Leaf fall/ dormancy
What resources does a vine need to survive?
- Water
- Sunlight
- Warmth
- Nutrients
- Carbon Dioxide (rarely a factor for growers)
What average temperature gives rise to dormancy?
<10°C
What temperature kills most vines?
Vitis vinifera is killed below -25°C
What average temperature gives rise to new growth in the spring?
Budburst is triggered >10°C
Compare the impact of a continental climate over maritime on budburst
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
Compare the impact of soil water retention on temperature and vine growth
Free draining soils hold less water, and heat up quicker encouraging earlier ripening
How and why do growers delay budburst?
Late winter pruning can delay budburst, to help avoid spring frost damage
What does a vine need during its ‘shoot and leaf growth’ phase?
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
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
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.
______ 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
What is coulure?
A high failure rate for fruit set
______ 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
What is millerandage?
Millerandage is a term for a high proportion of seedless, smaller grapes.
What are the key stages of grape development?
- Berry formation
- Veraison
- Ripening
- Extra-ripening
What compounds accumulate during initial berry formation?
Tartaric acid Malic Acid Aroma compounds/ precursors Methoxypyrazines (herbaceous flavours) Bitter tannins
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)
What are anthocyanins?
Compounds that give black grapes their colour
What compounds give black grapes their colour?
Anthocyanins
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
What are terpenes?
Terpenes are aroma compound that gives floral and citrus aromas. e.g. the grapey aroma in Muscat
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
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)
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
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
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
Which wine growing areas are particularly reliant on irrigation?
Argentina, California, South Africa and Australia
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
What are the top 5 vine nutrients and their purpose?
- Nitrogen is required to form proteins and chlorophyll
- Potassium - regulates water
- Phosphorus - used in photosynthesis
- Calcium - used in cell structure and photosynthesis.
- Magnesium - in cholorphyll
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.
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
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.
_____ 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
What are the minerals particle types that can make up soil?
Sand (large), silt (medium), clay (fine)
_____ describes a soil with moderate proportions of _____, ______ and ______
LOAM describes a soil with moderate proportions of SAND, SILT and CLAY
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
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)
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
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)
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
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
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
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
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
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
Who developed the concept of biodynamic viticulture?
Rudolf Steiner and Maria Thun