7. Canopy Management Flashcards
what are the aims of canopy management?
- maximize effectiveness of light interception by vine canopy
- reduce shade within canopy
- ensure uniformity of microclimate for grapes so they ripen uniformly
- promote balance between vegetative and reproductive functions of vine
- arrange canopy for ease of mechanization/hand harvesting
- promote air circulation to prevent disease
- vine balance
what is vine balance?
suitable balance between vine vigor and it’s yield. not over cropped and not under cropped. there is a link between yield of vine and quality of the fruit
what is a vegetative cycle?
If a vine is under-cropped, there is not much fruit to ripen, therefore the vine focuses more on green growth versus fruit growth and ripening. This leads to a dense canopy and lower quality fruit. Reduced fruitfulness in the season leads to less fruit in the next season, and so on
what is under-cropping?
when the yield of fruit is too low for the vigor of the vine. leads to vegetative cycle
what is over-cropping?
When the yield is too high for the vigor of the vine. leads to weak vines for future yields.
what determines vine vigor?
-growing environment: soil fertility, climate, natural vigor of vine, choice of rootstock, disease, wine style, vine age
When are decisions made that influence the number of shoots and potential yields?
Winter pruning is the key time period
explain how vine balance is relative
the yield at which a vine is balanced will depends on the natural resources of the vineyard, planting material, age of vine, presence of disease, and wine style
what influences optimum vine density?
vigor of the vine (which is influenced by natural resources and planting materials), type of trellising , access needed between vines.
what determines within-row spacing?
- vine vigor
- low vigor vines, VSP trained, can be planted closer together within the row to maximize vineyard land
- high vigor vines need more space, or risk overlapping canopies which increase shade and reduce ripeness and quality.
Why are vines in dry regions, without irrigation, planted at low density?
so roots may spread out without competition from other vines in search for as much water as possible.
why is between-row spacing important?
so one row does not shade the next
-vigorous vines that are high-trained and trellised need greater spacing between rows.
row orientation depends on what?
climate and logistical factors, winds, sunlight exposure, slope (for mechanization)
vine training and trellising depends on what three things?
- vigor of the vine
- site topography
- need for mechanization
what effects vine vigor?
natural resources (temp, water, nutrients), planting material (grape clone, variety, rootstock), presence of disease (can lower yields), human interventions (limiting irrigation, low vigor rootstocks)
why’s topography important regarding trellising?
many trellising systems cannot be used on steep slopes or windy sites.
Why is considering mechanization important for trellising?
certain trellising systems are better suited for mechanization - VSP
What is head training?
-relatively little permanent wood. Can be spur-pruned or replacement cane pruned
what is cordon training?
these vines typically hav a trunk and one or more permanent horizontal arms of permanent wood (cordons). Usually spur-pruned. Takes longer to establish than head training.
what are the two types of vine training?
head training and cordon training
what are the two types of winter pruning?
Spur pruning and replacement cane pruning
describe spur pruning
spurs are short sections of one year old wood (shoots from last growing season) that have been cut back to only 2-3 buds. Spurs can either be distributed along a cordon (cordon training) or around the top of the trunk (head training). Easier to carry out than replacement cane and can often be mechanized.
describe replacement cane pruning
canes are longer sections of one year old wood and can have 8-20 buds. they are typically laid down horizontally and need tying to a trellis for support and positioning. More complex than spur pruning and required skilled labor to select suitable canes and train them.
How does the number of buds left on a vine influence the balance of the vine?
the number of buds left depends on the vigor, more buds left for higher vigor vines. this influences the number and size of shoots in the growing season, and amount of fruit.
Why would a vineyard be untrellised?
If unable to be mechanized due to steep slope, vineyards are in hot, sunny, and/or dry conditions which restrict vigor.
-simple, inexpensive, but cannot mechanize
Vertical shoot positioning trellis systems are best suited for which vines?
low to moderate vigor
Advantages of VSP trellising?
- simple
- can be used on both head trained, replacement cane-prune vines AND cordon-trained, spur-pruned vines
Why would a grower use a more complex system than VSP for trellising vines?
If a vine is vigorous and ripens high yields of fruit, VSP would create dense canopy
Why prune in summer?
- enhances grape ripening
- reducing chance of fungal disease
- makes vineyard easier to manage
types of summer pruning?
disbudding shoot removal shoot positioning pinching shoot trimming leaf removal crop thinning/green harvest
describe disbudding
removal of buds to manage vine balance and yields, and to remove buds that are poorly positioned. disbudding late in the spring can be used to adjust the number of buds and bring vine into balance. also to remove buds of non-fruit bearing shoots.
describe shoot removal
removal of lateral shoots that are infertile or poorly positioned. helps maintain open canopy
describe shoot positioning
shoots tucked into trellis to organize canopy and help mechanization
describe pinching
removes the shoot tips at flowering to improve fruit set
describe shoot trimming
cutting shoots to limit growth and reduce canopy thickness. enhances fruit ripening by reducing competition for carbs.. lowers disease pressure by providing better air circulation
describe leaf removal
removing leaves to reduce shading of fruit and enhance ripening, will also lower disease pressure through better air circulation and spray penetration.
*excess removal can increase chance of sunburn in hot climates
What determines the number of buds left on the vine during pruning?
The vigor of the vine. More buds are left for more vigorous vines.
