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Grape Growing

Viticultural Techniques

  • Vines are usually pruned during dormancy, but some growers wait until the sap begins to rise in the early spring. Pruning determines the number of buds on the vine and, thus, influences the potential yield of the vineyard site. Pruning is also done to ensure a regular yield from the vine, since the vine will produce fewer bunches, but each bunch will weigh more than it would if left unpruned.

    There are essentially two types of pruning; spur pruning and cane pruning. In spur pruning, each cane, or wooded shoots from the previous year, is cut short to two buds, while in cane pruning they are left much longer, six to twelve buds each.

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  • Grape vines are trained to grow in a particular fashion in order to make vineyard work easier. The simplest form of training is bush training, in which vines are staked and grow independent of a trellising system. The vine is spur pruned, with the canes all coming off the center of the vine or head. As the shoots grow, they are sometimes tied together to give the vine shape, or gobelet. This system is used in warm countries because it provides the grapes with needed shade and because there is less risk of rot and mildew. Bush training is less expensive to install because no wires or supports are needed, but can be costly to maintain because vines trained in this method must be worked and picked by hand.

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  • Cordon training is a type of spur pruning. Spurs are spread out along a horizontal cane or cordon and are trained vertically on wires. This is called vertical shoot positioning or VSP. This type of training allows for the use of machines in vineyard maintenance and harvest and is widely used in California and other New World areas. Cordon training is also used for Pinot Noir in the Champagne region.

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  • Guyot training is a head trained, cane pruned system, where one to four canes are tied to a support wire. The buds along these canes send out the shoots, which are then trained on wires. Vines trained in this way provide grapes with more sunlight. This system is most often used in cooler regions where shading the grapes can prevent ripening, and the vines are exposed to the dangers of mildew and rot.

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  • During dormancy, some growers apply pre-emergent herbicides. Some growers chose to instead allow grass or other cover crops to grow. Cover crops prevent erosion, help add to the biodiversity of the soil, and prevent soil compaction, because tractors are not used. Tractors can damage the soil by impeding the flow of air and water. In some regions cover crops are not practical because they absorb too much water and too many nutrients that the vines need.

    Organic and biodynamic growers will work the soil to remove weeds at this period of growth, often using a horse instead of a tractor.

    Prior to flowering, any earth mounded up around the base of the vine to protect it during the winter is dispersed. At this point, growers who use beneficial bugs to fend off other harmful bugs, will release them into the vineyard. Organic and biodynamic growers who use copper and sulfur sprays to combat rot will begin to spray at this time.

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  • After flowering, the vine and fruit continue to grow and develop. During this stage of growth, the main objective of the grower is to protect the crop from pests and disease, including rot and mildew. Growers who practice sustainable agriculture will spray for rot and mildew only as needed, and not on a predetermined schedule. Growers who employ traditional fungicide practices will spray on a regular schedule from June up to three weeks before harvest.

    Each grower determines the treatments that are necessary for each vineyard and these will continue throughout the summer. Growers in warm, dry climates are able to operate with fewer chemicals, since the climate is not conducive to rot and mildew.

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  • In addition to fungal diseases such as rot and mildew, viral diseases like leafroll and fan-leaf and bacterial infections such as Pierce’s Disease (PD) can cause problems in the vineyard. Viral diseases can decrease yield but will not kill vines, but PD is almost always fatal.

    In addition to disease there are a host of pests, some that can be treated and some that cannot. Among the most difficult to treat are phylloxera and nematodes. These are small aphids that infect the roots of the vines, cause damage, and eventually kill the vine. These pests originated in North America, where the indigenous species of vine developed tolerance to them. The fine wine grapes of Europe had not and were thus killed when the pest was introduced into European vineyards during 19th century horticultural experimentation.

    Besides phylloxera and nematodes, grape moths and spider mites are common pests that can severely damage vines, but they are much more easily treated. Other pests, such as birds, rabbits and deer consume the fruit and can be difficult to deter.

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  • In addition to these mostly standard practices several other treatments can be used. Irrigation is frequently used in many New World winegrowing regions, although it is illegal in much of the Old World. In areas where rain falls throughout the year, such as Europe, irrigation is not normally necessary and could be easily abused to achieve higher yields. In many parts of California, Australia and South America, grape growing would not be possible without irrigation because the rainfall is insufficient and mostly falls only in the winter.

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  • Some growers use mulch organic matter (organic matter, such as manure or straw) to enrich and nourish the microorganisms in the soil. This can sometimes lead to problems with rot and mildew in wet or humid areas. Today, plastic sheeting is another way of mulching. Plastic strips prevent water from evaporating and limits the absorption of unwanted rain. Plastic also warms the soil which helps roots develop.

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  • Canopy management refers to a variety of practices intended to lessen the foliage or canopy and allow more air circulation and light to reach the grapes.

    There are several different effects of canopy management, which can increase photosynthesis when applied correctly. Shaded leaves in the interior of the canopy use more sugar than they create, but with increased photosynthesis, more sugar is created. At the same time, vine respiration increases as more leaves are exposed to the sun, lowering the acidity of the grapes. Yield per vine increases as it is exposed to more sunshine because more clusters develop, cluster weight is higher, and photosynthetic activity is increased.

    In general, there is an optimal ratio of leaf canopy to fruit clusters for each grape variety. When this ratio is maintained, grapes are produced with optimal ripeness, balance, acidity and physiological maturity.

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  • Green harvesting goes hand in hand with canopy management because when the leaves receive more sunlight, the vine grows more fruit. Some growers “green harvest,” also called "vendage vert" or “drop fruit” to lessen the overall fruit load and potentially improve the quality of the remaining grapes. Some growers prefer to regulate fruit load with winter pruning because they believe green harvesting can create imbalance in the vine's overall production.

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  • Strategies that a grower chooses can be characterized in several different ways. So-called “traditional viticulture” nourishes a vine through the use of fertilizers and takes preventative action against rot and disease by spraying on a regular schedule. Growers who practice sustainable agriculture or "lutte raisonnée" are generally opposed to massive chemical treatments and do not spray on a scheduled basis but rather wait to see if treatments are necessary. Each treatment is limited to the smallest possible amount. Integrated pest management or lutte integreé takes this approach further, and uses non-chemical means such as predator bugs wherever possible to fight against pests. Organic viticulture opposes the use of synthetic fertilizers, pesticides and herbicides. The rules for organic production vary in each wine producing country.

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  • Organic growers view the soil as a living world and act to best preserve this life. Such growers do not use inorganic sprays that do not decompose in the vineyard soil. The same is true of biodynamic growers. Biodynamic growers take organic viticulture one step further by integrating wine production into the motion of the universe as a whole. Accordingly, biodynamic growers time their movements according to the stars and make every effort to respect the mysterious forces of nature. Organic rules are legally defined and administered nation by nation, while biodynamic growers depend on certifying bodies such as Demeter and Biodivin.

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