WG-MR-1-TABLE GRAPESby Sanne Kure-Jensen
Most table grape varieties grown in the eastern United States are descended from Vitis labrusca. They ripen over an 8-10 week period in late summer to fall. Bruce Reisch of Cornell University recommended commercial grape growers, like all growers, consider their market before planting to ensure there will be buyers for their fruit.
Mars, Marquis and Vanessa varities work well for PYO operations. Mars is a blue seedless grape that grows well in warm areas. Its berry skin is tough, but it separates easily. Clusters are medium-sized and prolific. Limit clusters and fruit production on young vines to aid establishment. This grape offers excellent disease resistance. Mars is a mid-season grape and moderately cold hardy.
Marquis is a yellow-green seedless grape offering large clusters with excellent flavor. Vines are moderately hardy (zone 5) and offer medium vigor and excellent productivity. This is an early to mid-season grape. Do not use giberrellic acid treatment with Marquis grapes. Cane girdling and cluster thinning may increase berry size and improve appearance, but are not required to produce an attractive cluster.
Vanessa is a red seedless grape with medium-sized, sweet fruit in medium-sized clusters. These grapes have good storage potential. Vanessa is an early-season grape. This grape has good to excellent cold hardiness and moderate vigor. Cornell researchers say the fruit texture is the “best of the red seedless types.”
Canadice is a red seedless grape with small berries in medium-sized dense clusters. This grape is more winter-hardy than most seedless grapes, with occasional trunk injury in some sites. It is an early-ripening grape.
Lakemont is a mild-flavored small seedless grape with compact clusters. It is a mid-season grape and less hardy than other grape varieties.
Himrod is a yellow-green, seedless grape that produces large clusters. It is an early-season grape producing sweet berries with honey-like flavor. Cornell considers this variety its most successful seedless table grape from its grape breeding program.
The largest annual expenses for grapes are pruning, tying and weed control. When soils are too fertile, grapes will need summer pruning and limited leaf removal, not just winter dormant pruning.
Consider disease tolerance when selecting grape varieties to match site conditions. Disease resistant varieties will be easier and less expensive to manage.
Winter cold tolerance is genetic and variety specific. Careful vineyard management may extend the range of marginal varieties. Factors affecting cold hardiness include vine health status, previous season’s crop load and degree of vine acclimation to cold preceding exposure to heavy frost. Cultural practices and weather anomalies can change a vine’s cold tolerance.
Harvest, Storage & Handling
Harvest early in the day after dew has dried. Bring grapes to cool storage promptly for best quality and storage potential. Typical berry storage life is 7-10 days. Store fruit close to 32 degrees Fahrenheit, without letting grapes freeze. Coolers should have high relative humidity (90 percent or more). Keep temperature constant to avoid condensation on cold fruit.
Table grapes require a lot of handling. Growers or farm staff should remove any discolored or spoiled fruit in the bunch. Customers want “perfect” bunches, but many grape varieties that thrive in the Northeast are fragile and cannot handle rough or excessive packing and transportation.
Packaging & Sales
Customers typically want small containers of grapes. Some farmers offer grapes in a 1-pint box (box holds about two-thrids of a pound). This packaging makes handling easy and minimizes shattering and loss. Successful table grape growers use PYO farm stands and local farmers markets to sell table grapes. Samples often lead to sales increases of 50 percent or more.