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Flashcards in The Vine Growth Cycle Deck (35)
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1

Grape vines stay dormant when the average air temperature stays below ______

10°C / 50°F

2

V. Vinifera plants are susceptible to cold temperatures. At what temperature do most V. vinifera plants begin to die?

-25°C /-13°F

3

Budburst happens in which type of bud?

Compound buds

4

What is a major concern for growers right after budbreak?

Spring frost

5

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

6

True or False,

Late winter pruning can delay budbreak

True!

7

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.

Water Stress

8

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

9

what conditions are needed for successful fruit set?

Warm temperatures between 79°- 90°F

10

Name the more adverse condition during fruit set

Rain
Overcast
Windy

Cold temperatures

11

What are the two common forms of irregular fruit set?

Coulure and Millerandage

12

Define Coulure

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.

13

Give some examples of grape varieties that are more susceptible to Coulure

Grenache, Cab Sauv, Merlot, Malbec

14

Define Millerandage

A condition of the grape bunch in which there is a high proportion of seedless grapes.

15

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.

16

What causes Millerandage?

Cold, wet and windy weather at pollination and fruit set.

17

What things begin to accumulate in the berry before veraison starts?

Tartaric and Malic acids
Aroma compounds and precursors
Tannins
Water

18

Why would having too much water and nitrogen delay ripening?

Water and Nitrogen promote shoot growth instead

19

What causes the red coloring in the grape skins?

Anthocyanins

20

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

21

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

22

How are the sugars for the grapes produced?

Photosynthesis in the leaves of the vine.

23

What is the ideal range for photosynthesis?

64 - 91°F

24

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

25

Name the two types of acid naturally found in grapes?

Malic and Tartaric

26

Which acid will fall off as the growing season goes on?

Malic acid

27

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

28

What part of the vine moves sugar from the leaves into the grape?

the Phloem

29

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

30

Sugars accumulate faster in warm dry conditions, but what is a potential side effect of rapid sugar accumulation?

Even though the grape may reach physiological ripeness, it may not have fully ripe phenolics