How to Cure Black Rot in Grapes

Black rot is a grape disease caused by the fungus Guignardia bidwellii. Initial symptoms of the disease include small brown circles on foliage. Eventually the foliage wilts, grapes turn brown, shrivel and turn hard. These hard, raisinlike structures are called mummies and the fungus overwinters on them. Curing black rot in grapes involves a two-pronged approach: cultural and chemical. Contact your county cooperative extension office for currently recommended fungicides for your region.

Things You'll Need

• Pruning shears
• Fungicide spray

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Instructions

1. • 1

     Remove all mummies and infected canes when you prune the dormant grape vines. Even just a few left on the vine can cause infection in new growth.

   • 2

     Clean the area beneath the grapevine. Destroy fallen mummies and clear away weeds.

   • 3

     Spray fungicide immediately before the grapevine blooms and continue until four weeks after blooming. Apply at the rate listed on the fungicide label and use the spray schedule suggested.