Ch 7 Canopy management Flashcards
Define canopy management
The organisation of the shoots, leaves and fruit of the vine in order to maximise grape yield and quality.
What are the key aims of canopy management?
- Maximize effectiveness of light interception by the vine canopy
- Reduce the shade within the canopy (depending on the climate)
- Ensure that microclimate for grapes is as uniform as possible so grapes ripen evenly
- Balance between vegetative and reproductive functions of vine (bearing fruit vs vigour)
- Arrange vine canopy to ease mechanisation and/or manual labor
- Increase air circulation to reduce probability of disease
Explain how a vine’s exposure to sunlight affects yields in current and future growing seasons.
Shade and sunlight affect vine’s organs in different ways.
In the shade, a bud will produce more vegetative structures like tendrils rather than inflorescences– this is the vine’s way of saying it needs to grow in order to reach sunlight. This reduces bud fruitfulness, and therefore yields.
When exposed to sunlight, a bud will instead produce more inflorescences, increasing bud fruitfulness and yields in the next growing season.
A vine canopy that is well exposed to sunlight will increase bud fruitfulness and hence has positive implications for grape yields in the next growing season
Through canopy management, grape growers can increase the leaf surface area that is exposed to sunlight. This increases photosynthetic capacity meaning the vine can ripen larger yields in the current growing season.
Describe the implications canopy management and a grape/leave’s exposure to sunlight have on the style and quality of the wine.
Promoting exposure to sunlight leads to:
- Greater photosynthesis –> increased sugar levels
- More tannins and greater polymerisation of those tannins, hence less bitterness
- Enhanced anthocyanin (color) development in black grapes
- Decreased malic acid - warmer grape temps promote breakdown of malic acid thru cellular respiration; in cool climates, acidity levels in wine could be too high
- More favorable aroma precursors/compounds - ie terpenes (fruity, floral aromas such as grapey in Muscat)
- Decreased methoxypyrazines (herbaceous aromas in Cab Sauv, Sauv B, Cab F)
Describe additional ways that canopy management can affect yields.
In sunny, hot climates, canopy management can be used to minimize sun exposure and provide grapes with a certain amount of shade. This will reduce incidences of sunburn, which can reduce quality and yields.
Canopy management can also influence yields and quality by reducing fungal disease pressure. Dense, shaded canopies make it harder for water to evaporate after rain or morning dew, providing suitable conditions for fungal disease development. Also dense canopies make it difficult to evenly spray fungicides. A well ventilated canopy prevents these issues and reduces chance of yields being affected by fungal disease.
Describe the state of a vine in balance.
pre véraison –> sugars and nutrients focused on shoot and root growth and storage
post véraison –> sugars and nutrients allocated to fruit and ripening, shoot growth is depressed;
light in canopy is improved bc canopy not becoming more dense anymore. This leads to high quality fruit and also increased bud fruitfulness the following year, so vine balance is preserved.
Describe scenarios in which a vine is not in balance.
Under-cropping - vine vigour exceeds fruit yield. Shoot growth continues because there is not enough fruit to ripen. This process competes with grape formation and ripening, can negatively affect these processes. Canopy will be more dense and shady, affecting quality of fruit and bud fruitfullness (hence yields) next season. Low yields in next season leads to under-cropping that year, cycle continues – vegetative cycle
Over-cropping - yield of fruit exceeds vine vigour. Vine will seek sugars from carbs stored in trunk, cordons and roots. Vine needs these carb sources in the winter, so vine is weakened in future years
What factors influence the amount of fruit on a vine and its corresponding balance?
- growing environment –> warm, water, fertile= vines can grow vigorously, lots of shoots and leaves; can ripen large yields; limited resources, poor water or soils = can’t grow as many shoots and leaves, low vigor, unable to ripen same crop levels
- grape varieties/clones –> some more vigorous than others (CS more vigour, will ripen larger yield than Merlot)
- rootstock
- diseases - viruses can lower vine vigour
- age of vines - 10-40 is optimum vigour
- wine style being produced - rosé wine grapes can sustain larger yields bc tannin ripeness not as imp
- canopy management - winter pruning (coming season), summer pruning (correcting during growing season to enhance vine balance and ripeness)
Explain yield and factors that influence yield
Yield is the measure of the amount of fruit produced (kg per vine or kg per hectare, tons per acre)
Yield at which vine is balanced depends on:
- natural resources of vineyard
- planting material (plus age of vine and presence of disease)
- wine style
Legal factors- EU legislation specifies max yield per set area
List the main canopy management techniques
- vine training
- winter pruning
- vine trellising
- plant vigour management (irrigation, cover cropping, etc)
- summer pruning –> disbudding, shoot removal, shoot positioning, pinching, shoot trimming, leaf removal, crop thinning/green harvesting
** key consideration when establishing vineyard, esp as it relates to vine density
Define vine density.
Vine density is the number of vines that are planted per hectare of vineyard. Range from as low as a few hundred vines per hectare to over 10,000 per hectare.
Considerations when deciding within-row and between-row spacing.
- Needs to be considered during vineyard establishment as it will influence within-row spacing and between-row spacing of the vines.
Between-row spacing is important because vine rows should not shade each other. Also width of any machinery needs to be considered.
** Low-density, widely spaced, trellised vineyards are usually cheaper to establish and maintain than high-density, tightly spaced vineyards - requiring less planting material and permitting easier mechanisation.
What factors influence optimum vine density? Describe scenarios
- vigour of vine (itself influenced by planting material and environment/natural resources)
- type of trellising system
- access needed between vines
- low-vigor, VSP trellised vine can be planted close together within row as individual vines are relatively small (too much within-row spacing doesn’t maximize vineyard land, $ implications in expensive sites)
- High-vigor need more within-row space- avoid overlapping canopies and shading, which reduces ripeness and quality
- Dry-regions, no irrigation - planted at low density to avoid competition for water
What considerations need to be taken regarding row orientation?
- North-south orientation provides most even sunlight exposure through the canopy
- West side receives warmer afternoon sun, so bunches on west side of canopy might need more shading
- Prevailing winds - 90 degree angle to direction of wind for protection
- Parallel to longest side of vineyard is most efficient
- On slopes need to be planted up and down slope or machinery slips
The optiumum method of vine training must be decided at vineyard establishment. What determines the most appropriate training and trellising method?
- Vigour of vine –> determined by natural resources (environment water, temp, nutrients), planting material (rootstock, clone, variety), disease; humans can impact natural resources like using deficit irrigation or low-vigor rootstocks to limit water
- Topography of sites - steep slopes, windy sites not good for trellising systems (ex Northern Rhone and Mosel vines trained on individual stakes)
- Need for mechanisation - VSP better for mechanisation, all fruit grouped in same area for each vine; bush vines, individually staked vines less uniform and not suited for mechanisation
Explain VSP trellising systems.
- most common type, one of most simple
- best suited to vines w low to moderate vigour
- vines shoots are trained vertically and held in place onto trellis, forming single narrow canopy
- can be used on head-trained, replacement cane-pruned OR cordon-trained, spur-pruned vines
- if on replacement cane-pruned, called Guyot (single or double guyot)
Discuss complex training systems
- suitable for high vigour vines that need more management to split canopy and reduce shade and maximise light exposure
- horizontal split: Geneva Double Curtain, Lyre
- vertical split: Smart-Dyson or Scott-Henry
ADV:
- best use of vineyard space and resources
- can produce high quality fruit and large yields
DIS
- more difficult to manage and mechanize
