WSU Extension

Hortsense

Common Diseases : Botrytis blight (Gray mold)
(revision date: 4/30/2013)


Biology
Water-soaked lesions appear and quickly become covered with a gray-brown mass of fungus and spores. Infection often occurs at injury sites. After initial infection, gray mold can spread into the adjacent healthy tissues. This fungus infects leaves, rhizomes, stems, flowers, and seedlings of many plants. The disease is strongly favored by mild, moist conditions and can survive on infected plant debris.
Management Options

Non-Chemical Management
  • Space plants to allow good air circulation and better light penetration.
  • Remove and destroy infected plant parts, if feasible. Also remove infected plant debris.
  • Avoid overhead irrigation. Manage irrigation to keep foliage and stems dry.
Select non-chemical management options as your first choice!

Chemical Management

Properly timed fungicide applications may be necessary in some situations. Read and follow label directions and precautions making certain that the product that you purchase is registered for the target host.

Images
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Caption: Botrytis on alder seedling
Photo by: R.S. Byther
Caption: Botrytis on aster
Photo by: R.S. Byther
Caption: Botrytis on ageratum
Photo by: R.S. Byther
Caption: Botrytis blight damage on geranium flower
Photo by: R.S. Byther
Caption: Botrytis blight damage on geranium leaf
Photo by: R.S. Byther
Caption: Botrytis on lilac
Photo by: R.S. Byther
Caption: Botrytis on lilac
Photo by: R.S. Byther
Caption: Botrytis on lily
Photo by: R.S. Byther
Caption: Narcissus smoulder
Photo by: R.S. Byther
Caption: Narcissus smoulder
Photo by: R.S. Byther
Caption: Botrytis on peony
Photo by: R.S. Byther
Caption: Botrytis on petunia
Photo by: R.S. Byther
Caption: Spore masses of redwood Botrytis blight
Photo by: R.S. Byther
Caption: Tulip fire damage on flowers
Photo by: R.S. Byther
Caption: Tulip fire damage: black sclerotia
Photo by: R.S. Byther
Caption: Tulip fire damage on leaves
Photo by: R.S. Byther
Caption: Botrytis gray mold on strawberry
Photo by: R.S. Byther