Ch 2 the Vine Growth Cycle Flashcards
What does a vine need to survive?
- Water
- Sunlight
- Warmth
- CO2
- Nutrients
When does winter dormancy occur in each hemisphere? And at what temperatures?
- start with leaf fall in autumn and ends with budburst in spring
N: November - March
S: May - September
Below 10C (50F) are too cold for vine to grow
What temperature will kill V. Vinifera?
Below -25C (-13F)
What temperatures can severely damage vines?
Below -20C (-4F)
When does budburst occur in each hemisphere? What happens during budburst?
N: March- April
S: September - October
** Buds well and open, green shoots start to emerge
What kicks off budburst?
- air temperatures above 10C/50F
- soil temperature - stony, dry, free draining soils (sand, galets, gravel) warm more quickly and can kick off budburst in colder climates or when earlier start is needed for ripening (like CS)
- Grape variety - temp required depends on grape variety (Merlot opens at cooler temps, Ugni Blanc at higher)
- early budding: Merlot, PN, Chard, Grenache (Burg, Bordeaux, Rhone)
- late budding: SB, CS, Syrah
- Human factors: winter pruning can postpone budburst
What kicks off budburst?
- air temperatures above 10C/50F
- soil temperature - stony, dry, free draining soils (sand, galets, gravel) warm more quickly and can kick off budburst in colder climates or when earlier start is needed for ripening (like CS)
- Grape variety - temp required depends on grape variety (Merlot opens at cooler temps, Ugni Blanc at higher)
- Merlot, PN, Chard, Grenache are early budding (Burg, Bordeaux, Rhone(
What is a hazard/risk affecting budburst? Give examples and elaborate.
Spring frosts are a problem during this time.
- In maritime climates where winter/spring temps are less marked, a warmer winter day can start budburst and any subsequent frost can harm burst buds, lowering yields (increasing issue in Bordeaux w Merlot w climate change)
- Early budding varieties also more prone to spring frosts - i.e. Merlot in Bordeaux, PN + Chard in Burg
- Winter pruning later in dormant period can delay budrbust - good protection against spring frost
When does shoot and leaf growth take place in each hemisphere?
N: March - July
S: Sept - January
What does vigour refer to? What does it depend on?
Vegetative vine growth - the growth of shoots, leaves and lateral shoots; which has implications on yield and ripening of grapes
Depends on
- Natural resources available to vine (temp, water, nutrients)
- Planting material (grape variety, clone, rootstock)
- Presence of any disease (virus lowers vigour)
What does a vine need during shoot and leaf growth? Why?
- Stored carbs - support initial shoot growth
- stored carbs can be low due to water stress, excessive leaf removal, mildew infections, excessively high yields in previous season - Nutrients - nitrogen, potassium, phosphorous
- Water - water stress can limit photosynthesis and shoot growth
When does flowering and fruit set take place in each hemisphere?
N: May- June
S: November - December
What happens during flowering and fruit set?
1 .Prompt buds burst producing lateral shoots
2. Compound buds remain dormant - need sunlight, temps above 77F, water and nutrients to maximize bud fruitfulness next season ** conditions in one season impact yields in next ***
What does flowering refer to?
The opening of the individual flowers within an inflorescence
What does fruit set refer to?
The transition from flower to grape after the pollen tube fertilizes the ovule and grape berry forms from ovules.
What are important conditions for flowering and why?
Warm conditions - minimum 17C/63F - earlier and successful flowering
Low temperatures cause flowering to last longer, causing uneven ripening
What percentage of flowers become grapes?
Anywhere between 0-60%, typically 30%
Describe the optimal conditions for fruit set. What conditions negatively impact fruit set and why?
Optimal temps of 26-32C/79-90F - so warm summer days
Rainy, windy, cold temps can result in irregular fruit set and reduce yields
Hot, dry, windy conditions can cause water stress and also reduce yields
Define coulure.
What causes coulure?
Coulure is the condition of the grape bunch in which fruit set has failed for a high proportion of flowers; this can reduce yields.
Caused by an imbalance in carb levels which can be caused by - low levels of photosynthesis due to 1. cloudy conditions 2. water stress SOLUTION: IRRIGATION, CANOPY MANAGEMENT - vigorous shoot growth diverting carbs, due to 1. fertile soils 2. heavy use of fertilisers 3. vigorous rootstocks *** SOLUTION: CANOPY MANAGEMENT
Which grapes are naturally more susceptible to coulure?
Grenache
Cabernet Sauvignon
Merlot
Malbec
** OJO Bordeaux varieties
Define millerandage.
What causes millerandage?
The grape bunch produces a high proportion of seedless grapes, which are smaller; this reduces volume and wine quality
Cold, wet windy weather at fruit set will cause millerandage (cold, wet summer).
When does grape development take place?
N: June- October
S: December - April
What are the four stages of grape development?
- Early grape growth
- Véraison
- Ripening
- Extra ripening
Describe early grape growth.
What factors impact this stage?
This is when green grapes start to grow in size and tartaric and malic acids accumulate. Methoxypyrazines and other aroma compounds develop. Tannins accumulate. Sugar levels are low.
too much water and nitrogen at this stage promote shoot growth rather than grape development; mild water stress is preferred to ensure grapes ripen on time before autumn weather/harvest.
Mild water stress will also speed up early growth; causing smaller grapes/reduced volume but with higher concentration of tannins/flavors/colors
**SOLUTION: CAREFUL IRRIGIATION/MONITOR WATER LEVELS
