7.1 The Aims of Canopy Management Flashcards
What are the 6 aims of canopy management?
- maximise the effectiveness of light interception by the vine canopy
- reduce the shade within the canopy
- ensure that the microclimate for the grapes is as uniform as possible so that grapes ripen evenly
- promote balance between the vegetative and reproductive functions of the vine
- arrange the vine canopy to ease mechanisation and/or manual labour
- promote air circulation through the canopy to reduce incidence of disease.
Why is it beneficial to maximise the leaf surface area that is exposed to sunlight?
- Increases the vine’s photosynthetic capacity (compared to a vine with a dense, shaded canopy)
- Increased ability to ripen larger yields
Why can dense canopies be problematic?
- Poor air circulation
- Dry out more slowly after rainfall or morning dew
- Provide suitable conditions for fungal diseases to develop
- When spraying fungicides, it is more difficult to ensure the spray reaches all areas of the canopy
What are the 7 positive effects canopy management has on grape quality?
- increased sugar levels
- increased tannin levels (greater polymerisation, leading to less bitterness)
- enhanced anthocyanin (colour) development in black grapes
- decreased malic acid – warmer grape temperatures lead to more malic acid being broken down in cellular respiration
- increased levels of some favourable aroma precursors and aroma compounds
- decreased methoxypyrazines (herbaceous characters)
- reduced risk of fungal disease
Describe unripe black grape characteristics.
- unpleasantly high levels of acidity
- harsh tannins
- unripe fruit character
(reduced wine quality)
Describe ripe black grape characteristics.
- good depth of colour
- ripe fruit aromas
- balancing acidity
- ripe tannins
What is the optimal crop load?
Allows grape grower to grow the maximum yield of grapes that have the required composition for the desired wine style and quality
Describe a balanced cycle of canopy management.
- After véraison, sugars and other compounds needed for growth are mainly allocated to the fruit and shoot growth is depressed.
- Because shoot growth is reduced, the canopy is less likely to become dense and shady, and light exposure in the canopy is improved, leading to high quality fruit.
- It also results in enhanced bud fruitfulness the next year, and the balanced cycle continues.
Describe a vegetative cycle of canopy management.
- If the yield of fruit is too low for the vigour of the vine, shoot growth continues through the vine cycle because there is not much fruit to ripen.
- The growing shoots and leaves compete with the grapes for sugar and other compounds needed for growth and can negatively affect grape formation and ripening.
- This leads to a dense, shady canopy, and hence lower quality fruit due to lack of sunlight interception.
- This may also result in low yields the next year due to reduced bud fruitfulness.
- Low yields in the next season may lead to under-cropping in that year and hence the vine enters what is known as ‘a vegetative cycle’.
What is under-cropping?
If the yield of fruit is too low for the vigour of the vine
What is over-cropping?
If the yield of fruit is too high for the vigour of the vine
What is the ideal amount of fruit on the vine to create the correct balance in a warm climate with ample resources? Explain why.
- Vines can grow vigorously, producing lots of shoots and leaves.
- With many leaves, the vines have a high capacity to photosynthesise and produce sugars and other compounds needed for growth.
- These vines can successfully ripen a large crop load.
What is the ideal amount of fruit on the vine to create the correct balance in a climate with limited resources?
- Vines will not grow, so many shoots and leaves will be low in vigour and therefore not be able to ripen the same crop levels.
What 5 factors determines the ideal amount of fruit to achieve a perfect balance?
- Climate
- Resources (Water, soil)
- Grape variety
- Choice of rootstock
- Wine Style
Name a variety with high vigour that will grow larger and ripen a larger crop load. Name a low vigour variety.
- High vigour: Cabernet Sauvignon
- Low vigour: Merlot