The Vine Growth Cycle

Question 1

Vine growth cycle

Answer 1

Dormancy
Budburst
Shoot and leaf growth
Flowering and fruit set
Grape development
Harvest
Leaf fall

Question 2

Dormancy

Answer 2

Below 50F
Survives on carbohydrate stores in roots, trunk, branches
Too cold (-4F can damage, -13*F can kill)
Winter pruning

Question 3

Budburst

Answer 3

Avg air and soil temps above 50*F
Continentality can aid in successful budburst- rapidly changing temps = uniformity. Less continental regions can have uneven budburst

Question 4

Shoot and leaf growth

Answer 4

Supported by stored carbs initially then by photosynthesis from matured leaves
Most of the energy of the vine goes towards vigor until flowering

Question 5

Flowering and fruit set

Answer 5

Warm temperatures-min 63*F
Sun

Question 6

Coulure

Answer 6

Fruit set fails in a high proportion of flowers
Unsuccessful ovule fertilization
Reduces yields
Caused by imbalance of carbohydrates- caused by low photosynthesis from cold cloudy conditions or high water stress or vigorous shoot growth diverting energy from inflorescence (fertile soils, applications of fertilizer, vigorous rootstock)
Grenache, Cab Sauv, Merlot, Malbec susceptible

Question 7

Millerandage

Answer 7

High proportion of seedless grapes
Ripen normally but are smaller and reduce volume yields
Can result from cold, wet, windy weather at fruit set
Chard, Merlot susceptible

Question 8

Grape development

Answer 8

Sunlight
Warmth
Mild Water stress

Question 9

Early Grape Growth

Answer 9

Tartaric and Malic acids accumulate
Aroma compounds and precursors develop- Methoxypyrazines
Tannins accumulate- sunshine on grapes promotes accumulation
Sugar levels low
Water flow to grapes high - transport via xylem
Too much water and nitrogen prolong grape development favoring shoot growth- can delay overall ripening
Mild water stress can expedite but reduces grape size/volume yield

Question 10

Xylem

Answer 10

Transport tissue that transfers water and some nutrients from roots to parts of vine

Question 11

Veraison

Answer 11

Green colored chlorophyll in skin cells is broken down
Skin becomes stretchy and supple
Black grapes synthesize anthocyanins

Question 12

Ripening

Answer 12

Cells expand rapidly
Sugar and water accumulate via phloem (faster in warmer areas due to transpiration)
Acid falls due to dilution- malic acid metabolized in respiration
Tannin, color, aroma precursors and compounds develop influenced by heat and light

Question 13

Length of ripening factors

Answer 13

Grape varieties- early vs late
Climatic conditions- sugar ripens quicker in warmer areas warm dry conditions but hot can shut vine down
Vineyard mgmt- high yields, excessive shading can slow
Time of harvest- desired style, logistics or natural factors like rain/disease

Question 14

Extra ripening

Answer 14

No more sugar or water transported to grape but transpiration continues so sugar’s concentrate