Midwest Grape Production Guide

Bulletin 919-05

Cultivar Selection

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 mid-winter and are ranked as follows: tender, 0°F to -10°F; slightly hardy, -5°F to -15°F; moderately hardy, -10°F to -20°F; hardy, -15°F to -25°F; and very hardy, -25°F to -35°F.

Figure 10. Norton (Cynthiana) is an American-type cultivar widely grown in the lower Midwest.

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. (See Figure 10 and Table 1.)

Table Grape Cultivars

Vinifera table grape cultivars, such as Thompson Seedless or Flame Seedless, do not have sufficient cold hardiness to be grown in the Midwest. Although Concord and many other seeded grapes such as Buffalo, Alden, Steuben, Seneca, Golden Muscat, Edelweiss, Swenson Red, Yates, and others are grown and consumed fresh, berries without seeds are most in demand for table use, and these will be listed separately (Table 2) due to their uniqueness. (See Figure 11.)

Figure 11. Marquis (L) and Jupiter (R) are new promising high-quality seedless table grape cultivars.

Since fruit appearance and berry size greatly influence marketability, special cultural practices, such as application of gibberellic acid sprays, girdling, and thinning, must be used to produce table grapes commercially. Each cultivar demands a special mix of these practices for optimum marketability.

A recent publication—Growing Table Grapes in a Temperate Climate, Michigan State University Extension Bulletin E2774—describes the cultural practices and special management needed to successfully produce table grapes in the Midwest.

Hybrid Cultivars

The French-American hybrids have been widely planted in the Midwest since the mid-1940s. This group includes new cultivars or interspecific hybrids produced by crossing European or Vinifera grapes with one of the American species. Many were introduced from French breeding programs, and the cultivar name often includes the name of the breeder—for example, Vidal (Vidal 256).

In addition to the hybrids developed in France, many newer hybrids have been developed by breeders in the United States. These new cultivars are being widely planted in the Midwest. Hybrids are generally used in wine production and possess more winter hardiness and disease resistance than most of the V. vinifera parents. The most widely planted hybrids have a wine flavor close to European grapes. (See Figure 12 and Table 3.)

Figure 12. Chambourcin (L) and Traminette (R) are grown successfully in the Midwest.

European Cultivars

European-type (Vitis vinifera) cultivars are most widely produced in warmer regions of the world such as California, Mediterranean countries (e.g., France, Italy, Spain, North Africa), and Australia. Examples of widely grown vinifera cultivars are Thompson Seedless, Riesling, Chardonnay, Cabernet Sauvignon, Cabernet franc, and Merlot. (See Figure 13.)

Although cultivars vary slightly, fruit buds of most vinifera are injured at temperatures of -10°F, and vines are often killed if the temperature reaches -15°F or lower.

Since the Midwest experiences these temperatures during many winters, V. vinifera should be grown only on the very best sites, and special cultural practices should be used to lessen vine injury. Even if special practices are used and all precautions are taken, vine injury and death can occur during exceptionally cold winters. (For example, in February 1994, temperatures dropped to between -20°F and -30°F over much of the Midwest.)

A description of several vinifera cultivars grown on the best sites in the Midwest is presented in Table 4.

FIGURE 13. Vinifera cultivars such as Cabernet franc (L) and Riesling (R) are grown successfully only in the best sites in the Midwest or in proximity to the Great Lakes. (Photos courtesy of Dr. Tom Zabadal.)

Special Cultural Practices Necessary for Vinifera Cultivars

1. Rootstocks: Vinifera cultivars are all susceptible to grape phylloxera (root form), which is endemic on wild grapes in the Midwest. Phylloxera feeds on the roots, weakening the vines, reducing yield and berry quality, and rendering the vine more susceptible to winter injury. Rootstocks resistant to phylloxera must be used and the selection based on the cultivar’s vigor and soil conditions. (See Table 5.)
2. Protection of Graft Union: Hilling or mounding soil over the graft union and several inches up the trunk each fall can help protect the graft union even if cold injury or death occurs in the top of the vine (Figure 14). A new trunk can be initiated from this protected area, and production is lost for only one year.

Recent work in Michigan demonstrated that a heavy application of straw was nearly as effective as soil. The soil or mulch must be removed in the spring to avoid rooting of the scion and losing the phylloxera resistance and growth influence of the rootstock. Un-hilled vines in areas with no snow cover were killed in 1994, while hilled vines survived to produce a new trunk.

FIGURE 14. Hilling-up of European grape cultivars is a common practice in the Midwest. Hydraulic grape hoe (L) during hilling in the fall; hilled-up vines (R) protect graft unions and trunks from cold injury during winter.



3. Crop Management: Many vinifera cultivars have the potential to crop heavily and if crop load is not controlled, the vine carbohydrate reserves are not restored. Vines with inadequate reserves of carbohydrates stored in the canes, cordons, trunk, and roots are more susceptible to injury from cold and will be injured at milder temperatures than vines with adequate carbohydrate reserves. Vines carrying an excessive crop also are delayed in hardening off in the fall.
4. Leaf Quality: Most vinifera are susceptible to disease such as mildews that reduce leaf photosynthesis and impair carbohydrate production. Thus, a more thorough spray program should be used to prevent leaf diseases.
5. Multiple Trunks: Since winter injury is probable, it is advisable to have multiple trunks (two to four) of different ages for vinifera. Often one trunk will be injured and develop crown gall, while another may escape (Figure 15).

FIGURE 15. Having multiple trunks is beneficial should winter injury occur. One trunk has been injured and has developed crown gall at the base, while the other trunk is still alive.