Selection of the proper cultivars to plant is a major step toward successful viticulture. Before planting, commercial growers should give serious thought to the market outlet and the requirements of the processor or consumer who will purchase the crop.
Cultivars that are in greatest demand or sell for the highest price also are often the most difficult to produce.
Key Factors:
Choosing a grape cultivar is based primarily on two major factors market outlook and viticultural characteristics. Some important considerations are listed here, and these factors should be studied prior to planting. These considerations are listed in the order of importance:
- Vine Hardiness: Tolerance to low winter temperatures and/or spring frosts is often the limiting factor in cultivar selection in the Midwest.
- Fruit Characteristics: For a new grape cultivar to have real commercial value, it must first produce fruit that results in wine, juice, or eating quality that is superior or equal to the quality of available cultivars.
- Season of Ripening: Selected cultivars should be able to ripen their fruit and wood (hardening off) prior to the first killing frost in a given site. Late cultivars, for example, require a long growing season.
- Tolerance of Diseases and Insects: Resistance to the most common and destructive diseases and insect pests generally is not available in the present commercial cultivars. New cultivars that exhibit at least limited tolerance to some diseases or insects are highly desirable. Susceptible cultivars require more expensive cultural practices and in many cases should be avoided.
- Vine Characteristics: In addition to fruit quality, vine characteristics and productivity also must be superior to those of the cultivar being replaced. It is difficult to obtain a new cultivar with both fruit and vine characteristics superior to one already established, but this is the objective of the grape breeders. If the new cultivar has not been thoroughly evaluated by experiment stations or established with growers in similar climates and soil conditions, a trial planting should precede any extensive commercial planting.
Three basic types of grapes are grown in the Midwest American, Hybrids, and European. The characteristics of cultivars in each type that have proven adaptability or have shown promise and potential in university and industry tests in the Midwest are presented in the tables on the following pages.
Although many factors influence winter hardiness, as previously described, generally the temperature ranges assigned to the hardiness classes are based on maximum cold hardiness in midwinter and are ranked as follows: tender, 0F to -10F; slightly hardy, -5F to -15F; moderately hardy, - 10F to -20F; hardy, -15F to -25F; and very hardy, -25F to -35F.
American Cultivars:
The American type (e.g., Vitis labrusca, Vitis aestivalis, Vitis riparia) has the widest distribution throughout the northern half of the United States. Major producing areas include the Great Lakes region, the Pacific Northwest, the Midwest, and eastern states from Delaware to New England.
Examples of important cultivars include Concord, Catawba, Delaware, Niagara, and Norton. Most American-type grapes are slip-skinned that is, the flesh separates readily from the skin. Generally, they are processed into juices, jams, jellies, wine, or sherry. Well-managed vineyards have high yields of six to 12 tons per acre. American-type cultivars are generally hardy and widely adapted in the Midwest.
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