Plant guide:🍇 Grapes
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Fungal

Black Rot on Grape Vines

Commonly affects: Vitis vinifera, V. labrusca (Grape)

Small tan spots with dark borders appear on leaves, while infected berries shrivel into hard, black, mummified fruit that often remains attached to the cluster.

Potential Causes

  1. 1Guignardia bidwellii fungus, overwintering in mummified fruit and canes
  2. 2Warm, wet spring weather favouring initial infection
  3. 3Leftover mummified berries from previous seasons acting as a spore source

Solution Steps

  1. 1Remove and destroy mummified berries and infected canes at the end of the season, since they carry the fungus into next year
  2. 2Apply a protective fungicide starting at bud break through fruit development
  3. 3Improve airflow through proper pruning and canopy management
  4. 4Remove infected leaves and fruit clusters promptly during the season

Prevention Tip

Removing every mummified berry from the vine and ground at season's end is the single most effective step in breaking black rot's disease cycle.

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