Big Vines And Cold Injury Shape Vineyard Management In Virginia
All growers face challenges presented by the environment in which they farm. These challenges shape the agricultural operations within a region. Winegrape production in Virginia is no different. The principal challenges are rainfall during the growing season (approximately 45 inches annually) and the potential for cold injury (both during vine dormancy and spring shoot development).
Keeping the vines alive is dependent on both site and variety selection in this harsh environment. Sites on convex land forms with high elevation relative to the surrounding area are optimum in this environment. The convex landforms promote drainage of cold air and moisture away from the vineyard to surrounding low lying areas. Virginia growers select varieties for moderate cold hardiness and loose cluster architecture with thick berry skins. ‘Cabernet Franc,’ ‘Petit Verdot,’ and ‘Petit Manseng’ are great varieties to grow in Virginia.
A surplus of water is made available to the vines in fertile, fine-textured deep soils. This water, coupled with warm growing seasons, leads to vigorous vegetative growth, often in excess trellis space and of how much is necessary to produce and ripen the crop. The excessive vegetative growth, coupled with humid conditions, creates conditions in which foliar fungal pests can thrive. Dense shaded canopies that often develop with vigorous vines mush be remediated to open canopies.
While all grapevine training systems share common objectives, the means by which these objectives are met will differ by environment.
Intercept More Sunlight
Most frequently vines are trained to vertical shoot positioning (VSP). Keep canopies open rather than congested through shoot thinning, shoot positioning, leaf pulling, and hedging, even though they represent many labor hours of canopy management every growing season. Open canopies allow leaves to intercept direct sunlight, promote air circulation around leaves to accelerate drying, and increase spray coverage.
A minority of vineyard acreage in Virginia utilizes divided canopy training systems such as Lyre, Geneva Double Curtain, and Smart-Dyson training systems. There are multiple advantages of these divided training systems.
For vigorous sites, a grower can use the excess vegetative growth to produce and ripen fruit rather than removing this growth with remedial canopy management. Additionally, the divided training systems help limit canopy congestion. Single or divided canopies are often hedged at least one time through the growing season.