Flashcards in The Vine Growth Cycle Deck (35)
Grape vines stay dormant when the average air temperature stays below ______
10°C / 50°F
V. Vinifera plants are susceptible to cold temperatures. At what temperature do most V. vinifera plants begin to die?
Budburst happens in which type of bud?
What is a major concern for growers right after budbreak?
How does soil type effect budbreak?
high soil temperature around the roots can encourage bud break.
Dry, free draining soils tend to warm up quicker than water storing soils
True or False,
Late winter pruning can delay budbreak
List some of the reasons a vine could have low vigour after bud break
low carbohydrate levels caused by excessive leaf removal, water stress, mildew infections, or high crop loads from the previous growing season.
What are some of the side affects from stunted shoot growth
Small, weak shoots
reduction in leaf number / Small leafs
improper flowering / grape bunches that do not fully ripen
what conditions are needed for successful fruit set?
Warm temperatures between 79°- 90°F
Name the more adverse condition during fruit set
What are the two common forms of irregular fruit set?
Coulure and Millerandage
Coulure is a condition of the grape bunch in which fruit set has failed for a high proportion of flowers.
It is caused by an imbalance in carbohydrate levels.
Give some examples of grape varieties that are more susceptible to Coulure
Grenache, Cab Sauv, Merlot, Malbec
A condition of the grape bunch in which there is a high proportion of seedless grapes.
What are some of the negative side affects of millerandage?
Potential loss in volume of wine produced due to smaller grapes
Some of the seedless grapes will stay small, green and unripe.
What causes Millerandage?
Cold, wet and windy weather at pollination and fruit set.
What things begin to accumulate in the berry before veraison starts?
Tartaric and Malic acids
Aroma compounds and precursors
Why would having too much water and nitrogen delay ripening?
Water and Nitrogen promote shoot growth instead
What causes the red coloring in the grape skins?
What happens to the grape during veraison?
Grape growth slows down for a few days
The cell walls become more stratchy and supple
the green-colored chloropyll in the skin cells break down
What happens internally during the ripening phase?
The cells expand rapidly
Sugar and water accumulate
Acid levels fall
Tannins, color and a number of aroma precursors and aroma compounds develop
How are the sugars for the grapes produced?
Photosynthesis in the leaves of the vine.
What is the ideal range for photosynthesis?
64 - 91°F
What two prolonged weather conditions can hinder sugar production/photosynthesis?
Cold weather and constant cloud cover
Very hot and dry conditions that lead to extreme water stress
Name the two types of acid naturally found in grapes?
Malic and Tartaric
Which acid will fall off as the growing season goes on?
Why do levels of Malic Acid decrease as the season goes on?
Malic acid can be used for respiration during the ripening phase instead of sugar
What part of the vine moves sugar from the leaves into the grape?
Can the grapes themselves transpire?
Yes, even though the grapes do not have stomata, a small amount of water can transpire through the grape skin