Site Selection (Three Factors)
Environmental: Use data to
determine average temperature, rainfall and sunlight, soil fertility and
drainage. Helps decide Varietal, Training, Plant Density and
Business: Access to utility infrastructure (power, water, etc), labor force and whether it can be machine harvested.
Grape Variety: Must suit climactic conditions, the must be a demand for the grapes, and in the EU there are legal restrictions.
Vine Management - Why Is It Necessary?
Left alone, vines will produce grapes sweet enough to attract brids, but not ripe enough for winemaking, and focus more on plant growth than fruit ripening. Viticulturists use plant density, pruning and trellising to control ripeness and quality.
A vine management system consisting of a permanent structure of stakes and wires.With no trellising, vines go unsupported.
The vine's permanent wood and canes are trained to follow the trellising system. It manages the direction and growth of the following years shoots. Shoot positioning affects the amount of sunlight that is intercepted by the leaves and exposure to sunlight, wind and rain of the shoots.
The removal of unwanted leaves, canes and permanent wood, either during winter of the growing season.
Winter Pruning: Purposed and Two Types
Purpose: To determine the number
and location of the buds, which will form shoots for the production of
fruit in the coming harvest.
Replacement Cane Pruning: One, or more, canes are retained, while the remaining are trained horizontally across the trellis. Also called guyot, single or double depending on number of canes retained.
Spur Pruning: Many two-to-three bud spurs are retained, distributed along a permanent cordon of old wood. This allows for mechanical pruning and significant cost savings, and is frost-resistant.
Trimming the canopy to restrict vegetative growth, direct sugar production to the grape, and can involve leaf stripping so the grapes are exposed to sunshine.
Bush Training System
A vertical stump of permanent wood is pruned to retain a number of spurs at the head of the vine. The shoots sprawl across the ground. Practical in hot, dry, sunny climates (Southern Rhone, Barossa Valley), not in cool areas because grapes are shaded and wouldn't ripen. Not suitable for mechanical harvesting. Sometimes referred to as Gobelet
Vertical Shoot Positioning (VSP)
Most common training system in the world, and may be used with replacement-cane or cordon-spur pruning. Single canopy of shoots are trained upwards, tied to trellis, and may extend to both sides or trunk or only one, then trained horizontally. Low trained for heat retention, high trained to avoid frost. Keeps vines separate, aerated, exposed, good for high density planting.
Big vine training systems are planted to low densities and ensure that all light is utilized. Lots of permanent wood. Can use VSP with a vertically split canopy, others train shoots downwards or have multiple canopies. Usually spur pruned, can be mechanically harvested. Developed to restrict vine vigor in high-nutrient areas.
Measuring Vine Vigor
Vine vigor is measured by the number and size of shoots and leaves it grows in a season. This is driven by nutrients, water, sunlight, and heat. Planting density, cover crops, number of buds per vine and rootstocks all can manage vigor.
Ripeness is achieved when a grape has the level of sugar nad physiological ripeness for the style of wine, far above what would occur in nature. Winter Pruning helps achieve this by defining number and location of buds. Cool sites need fewer buds, because it is hard to ripen many grapes.
Yields are measured in terms of weight (Kg per hectare) or volume (Hectolitres per Hectare). Producers may have contractual or regulatory obligations to meet Yield requirements. Green harvesting limits yields.
Removing immature grapes shortly after Veraison. Risky, because the vine may compensate for the loss by increasing the size of the remaining grapes, diluting their flavors.
Microscopic worms that attack vine roots and may transmit viruses. Root damage reduces yields and leaves the vines susceptible to infection, and water and nutrient stress. Treatment is hard, so prevention by soil sanitisation is recommended, as is planting nematode-resisting rootstock.
Birds and Mammals
They eat grapes, and cause damage that allows rot. Birds, deer, boar, etc. Netting, fencing and bird scares are solutions.
Insects and Arachnids
Caterpillars, moths, beetles, mites, aphids, etc, all feed on plant matter, damaging shoots and leaves, limiting photosynthesis, damaging ripening fruit, and even tainting wine flavor.
Thrives in warm, humid conditions. Attacks green parts of the vine, especially young leaves. Leaf damage impedes ripening, and damage to berries reduces yield.
Likes warm, shady conditions and develops on green parts of the vine. It can affect bud development and shoot growth. Affects bud development and shoot growth, can cause grapes to split and gives wine a moldy, bitter taint.
Likes damp and humid conditions. Can damage parts of the vine but causes the greatest problems by attacking immature berries. Taints flavor, reduces yields, and causes color loss in black fruit.
Traditionally, treated by spraying with sulfur-based (downy) or copper-based (powdery) sprays, but now chemicals are often used. Spraying is done by tractor, helicopter, or airplane. All spraying must stop before the harvest. It can also be reduced by canopy management.
Desired Gray Rot, caused by the fungus Botrytis Cinerea. It attacks when the grapes are ripe, encouraged by humid misty mornings and warm, sunny days. The fungus punctures the grape skin, allowing the water to evaporate. Acids and sugars are concentrated, and other flavors develop. These grapes go into the world's best sweet wines.
Fanleaf Virus & Leafroll Virus
Does not kill the vine, but dramatically reduces yields, are highly contagious and persistent. Spread via cuttings or nematodes. Only way to eradicate is to dig up vines and sanitize earth, and should not be replanted.
A fatal bacterial disease spread by small insects called Sharpshooters. No cure exists and vines die within five years. Isolation is the only preventative measure.
Integrated Pest Managemnt
An Alternative Viticulture Practice that uses chemicals only when absolutely necessary. Vineyards are monitored and chemicals deployed only when required. Predator populations control pests.
An Alternative Viticulture Practice no synthetic chemicals are used, but fungal control is very hard.
An Alternative Viticulture Practice where no synthetic chemicals, homeopathic remedies ward off vineyard pests and disease, and vineyard practices are tied to the planets and stars.
Fast, full-time harvesting. Vines are shaken and then fallen grapes are collected. The harvest is culled at a sorting table, as the harvester collects everything on the ground. Best for flat or gently-sloping vineyards. Cannot be used for wine styles that require whole bunches, like Beaujolais or Champagne.
Slower, more labor-intensive, but permits grape selection. Essential for botrytised grapes. Stalks are retained. In steep regions like the Mosel, the Douro and the Northern Rhone, there is no choice.
The Vineyard Cyclet: Terms and Dates
Budburst: March/April or Sept/Oct
Shoot & Leaf Growth: March-August or Sept-March
Flowering and Fruit Set: May/June or Nov/Dec
Veraison and Berry Ripening: July-Sept or Jan-March
Harvest: September/October or March/April
Winter Dormancy: Dec-March or July-September
In the spring, when the avg temp is 10C, buds swell and burst, growing into new shoots. Spring frosts can kill new buds. Earth is taken away from the graft union. Spraying for fungal diseases and pests begins.
Shoot & Leaf Growth
In late spring through summer, shoots grow until the vine flowers. Vine needs water and nutrients. Shoots are trained to the trellis to ensure canopy remains open. Spraying as necessary.
Flowering and Fruit Set
During flowering, vines need 15C temperatures. plus plenty of sunlight and little to no rain, or pollination will be inhibited. Fruit set occurs when a flower starts to develop into a grape. Unpollinated flowers drop off. Spraying continues.
Veraison and Berry Ripening
Veraison is the point that grapes begin to ripen, signaled by a change in the color of the grapes. Until then, all grapes are green, and black varieties turn red and purple, while green ones turn golden and translucent. Birds begin to eat them. Grapes swell with water, sugar levels rise and acid levels drop. Physiological ripening also happens. Requires warmth and sun, and mild stress helps. Summer pruning ensures an open canopy, and green harvesting controls yield and quality. Spraying continues.
Cold weather ends growing season. Shoots become woody, vine stores carbohydrate reserves in roots. Leaves fall off and the vine becomes dormant. Earth may be piled on the graft to protect it. Winter pruning takes place.