2. Vine Growth Cycle Flashcards
When is vine dormancy in then northern hemisphere, and what does the vine need during this time?
November-March
- vine needs temps below 50ºF
- adverse: temps too cold or too warm
When is budburst in the northern hemisphere, and what does the vine need during this time?
March-April
- Vine needs average air and soil temp above 50ºF
- Adverse: Frost and cold soil
When is shoot and leaf growth in the northern hemisphere, and what does the vine need during this time?
March-July
- Vine needs stored carbohydrates, warmth, sunlight, water, nutrients
- adverse: low carb levels, water stress
When is flowering and fruit set in the northern hemisphere, and what does the vine need during this time?
May-June
- Vine needs warm temps, minimum 63ºF, sunlight, warmth, water, and nutrients for bud fruitfulness in the next growing season.
- adverse: rainy, cloudy, windy, cold
When is grape development in the northern hemisphere, and what does the vine need during this time?
June-October
- Vine needs sunlight, warmth, mild water stress
- Adverse: too much water and nutrients, excessive shading, very cold or very hot temps day and night.
What is respiration?
the process by which energy is released from food substances, in this case, sugar.
What signals the beginning and end of winter dormancy?
Winter dormancy typically starts with leaf fall in the autumn and ends with budburst in the spring
Without leaves for photosynthesis, how does a vine sustain itself over the winter?
Stored carbohydrates from the previous growing season in the roots, trunk, and branches.
What is needed for buds to burst?
average air and soil temps above 50 degrees F
What can advance or delay budburst?
Air Temp
Soil Temp
Grape Variety
Human Factors
(Air Temp) How are buds affected in Continental climates vs Maritime climates?
Regions the have a marked difference in temperature between the various seasons (continental climates) can be advantageous for successful budburst. Rapidly increasing temperatures in the spring mean that bdburst can be relatively uniform which has positive implications for the homogeneity of ripeness (even)
Regions with less contrast between winter and spring temperatures (maritime), butburst can be less synchronized. Mild winter days can cause early budburst, and cold days and frosts that follow can potentially harm new buds, leading to lower yields.
Describe how different soils can affect soil temperature and how does that relate to budburst?
Higher soil temps around the roots encourage earlier budburst. Dry, free-draining soils such as sand, tend to warm up more quickly than water-storing soil such as clay. This can be advantageous in cool climates where an early start to the growing season improves the chance of ripening.
What is Coulure?
A condition of the grape bunch in which fruit set has failed for a high proportion of the flowers. This occurs when ovule fertilization is unsuccessful and therefore no grape develops. Some couture is normal, but excessive couture can reduce yields dramatically.
What causes coulure?
Imbalance in carbohydrate levels. This may result from low rates of photosynthesis, which may be caused by cold, cloudy conditions, or hot, arid conditions with higher water stress.
It can also result from vigorous shoot growth diverting carbohydrates from the inflorescence - very fertile soils, heavy application of fertilizers, rigorous rootstocks can all cause strong shoot growth and therefore lead to coulure.
What is Millerandage?
A condition of the grape bunch in where there is a high proportion of seedless grapes.
