A hot, dry climate, well-drained soil and plenty of water is needed to grow grapes. Extended periods of cold weather (below 0 ℉) will kill vines, yet a period of winter dormancy is needed. Special care should be taken for grapes grown in areas where winter freezes are common.
References: Ohio State University, Texas A&M AgriLife Extension.
TYPES, VARIETIES & CUTS
Per the U.S. Department of Agriculture (USDA) there are four types of grapes: American, European, Juice, and Muscadine. These four types cover the array of table, wine, juice, and raisin grapes grown.
American grapes can tolerate cooler climates and will grow well in the Midwest. European grapes are most typically used for wine making but they can also be used as table, juice, or raisin grapes. These grapes lack cold-hardiness and are better suited to a warmer climate.
Any variety of sweet grapes can be made into grape juice although the most common grape used is Concord. Muscadine grapes, which grow wild in North Carolina and much of the Southeast, are thought to be the first native American grape. Grapes for juice are picked individually and not by the bunch because in many of the varieties, each grape in the cluster ripens at a different time. This can be true for Muscadine grapes as well, which grow in loose clusters with berries falling to the ground when ripe.
Some varieties are not recommended for certain regions. For instance, grape varieties such as Jupiter, Saturn, and Sunbelt can be susceptible to Pierce’s disease (see below for further information) and should not be grown in areas where the disease has been a significant threat.
References: Iowa State University, University of Arkansas Division of Agriculture, USDA.
PESTS & DISEASE
Pierce’s disease is spread through insects infected by Xylella fastidiosa (bacteria) when they feed on grapevines. Some varieties are tolerant of the disease (for instance, Muscadine) but susceptible varieties will experience vine death as there is no method of treatment. Black rot is spread by dried berries left on the vine or on the ground over winter. Tan spots with tiny black specks appear one to two weeks after infection. To prevent black rot, remove all dried berries from vines before winter. Anthracnose causes round holes in leaves and can be controlled by the same fungicides used to control black rot.
Phylloxera is an insect that kills roots of grapevines by laying eggs on rootlets (Muscadines are resistant/tolerant). Grape berry moth larvae feed on blossoms and berries. Insecticides should not be applied until after the grapes have reached the size of small peas or beneficial pollinators will be destroyed. Once the larvae proceeds to the second stage (moth) they are increasingly difficult to control. To prevent hibernation of moth pupae, leaf litter should be cleaned up or buried before winter. Grape leafhoppers feed on the underside of leaves resulting in a stippling look to the affected leaf. Leafhoppers are quite small; they can do serious damage before their presence is known.
References: Texas A&M AgriLife Extension, University of Kentucky, USDA.