Grapevines can yield up to 50 years of grape production, but they require careful planting and maintenance. These vines have specific growing needs and fall prey to a range of pests and diseases. Anthracnose, or black rot, attacks shoots, fruit and leaves of the vine, restricts fruit production and kills new growth. The Iowa State University Extension calls this the most dangerous grapevine threat in their state. Diagnose anthracnose early and treat the vines for in order to save your fruit harvest.
Diagnose anthracnose for correct treatment. Look for sunken, dark spots on the canes, foliage and grapes of the vines. The centers of the spots may be white, gray or missing completely. Young leaves are most susceptible to anthracnose, which causes these leaves to twist and become deformed.
Cut out infected foliage, canes and fruit to minimize spreading. Rake all litter from below the infected grapevines, and dispose of the liter and pruned foliage. Put 2 inches of organic mulch around each grapevine to minimize soil splashing and prevent further infection.
Put the grapevines on a biweekly fungicide schedule. Use fungicides that target anthracnose for best results. Discontinue the applications when the grapes reach mature coloration, for a safe harvest.
Spray the grapevines again in spring, before they break dormancy, with liquid lime sulfur spray. This application aids in preventing anthracnose.
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