Canopy Management Flashcards
Aims of Canopy Management
Maximize effectiveness of light interception by the canopy
Reduce shade in the canopy
Ensure the microclimate for the grapes is as uniform as possible so grapes ripen evenly
Promote balance between vegetative and reproductive functions of the vine
Arrange the canopy to ease mechanization or labor
Promote air circulation to reduce the risk of disease
Sunlight Exposure Impacts
Vine organs (buds, leaves, fruit) develop differently if in shade vs sun
Exposure to sun is associated with greater bud fruitfulness (number of inflorenscences developing in the latent bud)
Shadyness promotes more vegetative structures (tendrils) in the latent bud. This is due to in the wild vines must grow vegetatively until they reach the sun where birds can see them and then produce grapes.
Increases sugar levels in the grapes through more photosynthesis
Increases tannin levels and polymerization of tannins leading to less bitterness
Enhanced anthocyanin development in black grapes.
Decreased malic acid - warmer temps lead to more malic acid being broken down in cellular respiration
increased levels of aroma compounds and precursors (such as terpenes which are the fruity florals in Muscat)
Decrease methoxypyrazines
Canopy Management and Vine Balance
Key aim of canopy management is vine balance which is needed to ensure successful grape ripening and sustained production over future seasons
Vegetative Cycle: Shade depresses bud break, bunch initiation, fruit set, berry growth. Fruit weight per shoot is reduced. Shoot growth is stimulated due to less fruit growth. Canopy density increases due to more leaf area
Balanced Cycle: Light stimulates bud break, bunch initation, fruit set, berry growth. Fruit weight per shoot is increased. Shoot growth is depressed due to more fruit growth. Canopy density decreases due to less leaf area.
If the yield is too low (under cropping) for the vigor of the vine, shoot growth continues which then competes with the grape for sugar and leads to a heavy dense canopy.
If the yield is too high for the vigor (over cropping) the vine may take sugars stored in the trunk, cordons, roots. The vine needs these in the winter and next spring and so this may weaken the vine.
The amount of fruit needed for balance will depend on the environment (how much light, warmth, water, soil nutrients) and the vine itself. Some are more vigorous than others. Cab Sauv is more vigorous vs Merlot. Age and disease also impact.
Canopy management techniques
Vine Training
Winter pruning
Vine trellising
Plant vigor management: fertilization, irrigation, cover crop, etc
Summer pruning: debudding, shoot removal, shoot positioning, pinching, shoot trimming, leaf removal, crop thinning, / green harvesting
Vine Density
Number of vines planted per hectare. Range from a low of a few hundred vines per hectare to over 10,000
Will influence the within and beween row spacing and so needs to be considered during vineyard establishment.
Optimal density is influenced by the vine vigor (natural resources and plant material), type of trellising and access space needed b/n vines.
Low vigor VSP can be plante close together as vines are small. High vigor will need greater spacing. Too close can lead to overlapping canopies and shading. Dry regions w/o irrigation may also be low density despite being small so roots can spread out and not compete for water
Width of machinery also a consideration
Overall low density widely spaced are usually cheaper to establish and maintain than high density tightly spaced. Require less planting material, trellising, and are easier to mechanize
Row Orientation
Depends on climate and logistics
Generally north south provides the most even sun exposure
But as afternoon sun is usually warmer than morning, grape bunches on the west side may require more shading to protect frum sunburn.
Prevailing winds may also play a role with growers orienting vineyards at a 90 deg angle to the wind direction to provide protection.
Logistically orienting parallel to the longest side of the vineyard is often most efficient.
Vineyards on slopes over 10% need to be planted up and down the slope rather than across so machinery doesn’t slip
Vine Training, Pruning, and Trellising Considerations
The vigor of the vine:
Topography of the site. Some trellises cannot be used on steep slopes or windy sites. Hence No Rhone and Mosel may be individually staked
Need for mechanization: some are better suited to mechanization (VSP) than others (bush)
Vine Training:
The shape of the permanent wood of the vine; typically either head trained or cordon trained.
Either can be low trained (trunk is short) to benefit from heat retained by soil, protect from wind or high trained (long trunk) to avoid frost or make manual interventions easier.
Head Training: Little permanent wood; usually the trunk with a few short stubs growing from the top of the trunk. Can be spur or replacement cane pruned.
Cordon Trained: trunk and one or more horizontal arms (cordons) of permanent wood. Usually spur pruned. Takes longer to establish due to amount of permanent wood.
Vine Pruning
Removal of unwanted parts of the vine.
Takes place in winter and summer. Winter very important as determines the number and location of buds that will form shoots in the coming growing season and hence impacts potential yield.
Spur pruning: spurs are short sections on one year old wood (shoots from last year that have lignified) that have been cut back to only 2 - 3 buds. Can be distributed along a cordon or around the head of the trunk (head training). Easier than replacement cane and can often be mechanized.
Replacement Cane: Canes are longer sections of one year old wood that can have b/n 8 and 20 buds. Laid down horizontally and need tying to a trellis for support and positining. More complex and requires skilled labor force to select and train.
Trellising
Permanent structures of posts and wires that help support and position the vine’s shoots. Tendrils will naturally curl around but shoots will likely also be tied.
Untrellised: typically head trained spur pruned and called bush vines. Simple, easy, inexpensive to establish. Shoots may droop down providing some shade. Usually in hot sunny locations (La Mancha) Not suitable for mechanization. Best in dry conditions which restrict vigor. Too much vigor here can cause too much shading. Wet conditions would promote disease given the density.
Trellised Vineyards: very common. shoots can be spread out to maximize light interception, increase air flow, and aid mechanization. Expensive to establish and maintain.
VSP: most common and one of simplest. Shoots are trained vertically and held in place on the trellis forming a single narrow canopy. Can be used on head and replacement cane (Single or Double Guyot) and cordon trained. good for low to moderate vigor
Complex training systems: These are for more vigorous vines where VSP might be too dense and shady. Can be split horizontally (Geneva Double Curtain or Lyre) or horizontally (Smart-Dyson, Scott-Henry). Harder to manage and mechanize.
Summer Pruning
Variety of techniques to keep the canopy maintained. Many in spring but some in summer. Usually to aid grape ripening, reduce chances of fungal disease, or making vineyard easier to manage. Most not all can be mechanized.
Disbudding: Removal of buds done to manage vin balance and yield or remove poorly positioned. Leave high number in winter in case some are damaged. Debudding in late spring can bring vine into balance or comply with yield regulations.
Shoot removal: often laterals that are poorly positioned or infertile. too close together, low down on trunk.
Shoot positioning: tucked into trellis wires to organize and facilitte mechanization.
Pinching: removing shoot rips at flowering to improve fruit set.
Shoot trimming: cutting shoots to limit growth and reduce canopy thickness. reduces competition for carbohydrates and lowers disease pressure through better circulation and spray penetration
Leaf removal: to reduce shading of fruit and enhance ripening. lowers disease pressure through better circulation and spray penetration. too much can lead to sunburn.
Crop thinning or green harvesting: removal of bunches to increase ripeness of those left. timed near veraison can enhance ripeness. If ripening has been ununiform may remove the least ripe to improve unformity and quality.
