Vine Growth Cycle Flashcards
What time of the year do vines go in to dormancy?
Northern Hemisphere: November - March
Southern Hemisphere: May - September
Why does dormancy occur?
Average air temperatures below 10°C (50°F) are too cold for the vine to grow and therefore in winter the vine is dormant.
How does the vine support itself during dormancy?
Until it has grown new leaves, the vine supports its growth by using stores of carbohydrates, mostly starch, accumulated during the previous growing season in the roots, trunk and branches.
What low temperatures are damaging to wines?
- Temperatures below −15°C (5°F).
- Temperatures below −25°C (−13°F) will kill most vines.
- Problematic during Winter in Canada, New York State and China
Which important vineyard activity is done during dormancy?
Winter Pruning
What is another word for budburst?
Budbreak
What is budburst?
When vine buds swell and open, and green shoots start to emerge.
What are four factors that determine when budburst occurs?
- Air Temperature
- Soil Temperature
- Grape Variety
- Human Factors (e.g. late winter pruning)
What are the temperature requirements for a bud to burst?
Average of 10°C / 50°F
Why can regions with continental climates be advantageous for successful budburst?
Rapidly increasing temperatures in the spring mean that budburst can be relatively uniform.
This has positive implications for the uniformity of later stages in the growing season, leading to a crop of grapes with even ripeness.
Why can regions with maritime climates be disadvantageous for budburst?
Budburst can be less synchronised and uneven.
Problems can occur when a few unusually mild winter days cause early budburst; any cold days and frosts that follow can potentially harm the newly burst buds, leading to lower yields.
How can soil temperatures encourage earlier budburst?
Higher soil temperatures around the roots encourage earlier budburst.
What types of soils are beneficial in cooler climates?
Dry, free-draining soils (e.g sandy soils) tend to warm up more quickly than water-storing soils (e.g. clay-rich soil). This is advantageous in cool climates where an early start to the growing season improves the chance of ripening.
What is meant by an ‘early budding’ grape variety?
Grape varieties that require relatively low temperatures at budburst.
Name three late budding grape varieties.
Cabernet Sauvignon
Sauvignon Blanc
Syrah
Name four early budding grape varieties.
Chardonnay
Pinot Noir
Grenache
Merlot
Is budding time linked to ripening time?
No, e.g. Grenache buds early and ripens late.
What human factors can influence budburst?
Carrying out winter pruning later can delay budburst. This is useful in areas prone to spring frost.
When is budburst in the Northern Hemisphere?
March - April
When is Budburst in the Southern Hemisphere?
September - October
When do shoots and leaves grow, in the Northern Hemisphere?
March to July
When do shoots and leaves grow, in the Southern Hemisphere?
September to January
What is Shoot and Leaf Growth?
When the shoots continue to grow, and leaves and inflorescences (a cluster of flowers on a stem) mature.
At what stage does the fastest rate of shoot and leaf growth occur?
The fastest rate of growth generally occurs between budburst and flowering.
What initially supports shoot growth?
Carbohydrates stored in the roots, trunk and branches of the vine support the initial shoot growth.
What supports shoot growth later in the growing season?
As leaves develop and mature, they provide energy for further growth via photosynthesis, and therefore need adequate warmth and sunlight for this to take place.
What four factors might contribute to low carbohydrate levels?
Excessive leaf removal
Water stress
Mildew infections
High crop loads in the previous growing season
What main problem can occur during shoot and leaf growth?
Water Stress
- can limit photosynthesis and shoot growth
- can limit nutrient uptake through the roots
What does stunted shoot growth lead to?
- Small, weak shoots
- A reduction in leaf number or smaller leaves
- Inflorescences that do not flower properly
- Grape bunches that do not ripen fully
- Poor quality
- Lower yields
What does a vine need during the shoot and leaf growth stage?
Stored Carbohydrates
Warmth
Sunlight
Nutrients
Water
Nutrients: Phosphorus, Potassium, Nitrogen
When is Flowering and Fruit Set in the Northern Hemisphere?
May - June
When is Flowering and Fruit Set in the Southern Hemisphere?
November-December
What happens to buds during Flowering and Fruit Set?
- New buds develop at the base of the leaf stalks (petioles) on the new growing shoots
- Prompt buds will burst within the growing season producing new shoots called lateral shoots
- Compound buds will remain dormant until the following spring and provide the shoots for next year.
(flowering and fruit set)
What buds form and when do they burst?
- Prompt buds will burst within the growing season producing new shoots called lateral shoots
- Compound buds will remain dormant until the following spring and provide the shoots for next year
(flowering and fruit set)
What four factors can limit bud fruitfulness (the number of inflorescences that will develop from a bud) in the next growing season?
- Shading of compound buds
- Temperatures that are too low (under 25°C / 77°F)
- Water stress
- Nutrient deficiency
(flowering and fruit set)
Why is the flowering and fruit set period important for the next year’s yield?
- Shading of compound buds, temperatures that are too low (under 25°C / 77°F), water stress and nutrient deficiency can all limit bud fruitfulness (the number of inflorescences that will develop from a bud) in the next growing
- Each inflorescence will become a bunch of grapes next year