(Botrytis Flower Blight, Botrytis Flower Spot, Botrytis Leaf/Stem Blight, Botrytis Leaf Spot, Gray Mold)
Host: Botrytis blight is one of the most common diseases in greenhouse crops. Hosts include african violet, azalea, begonia, caladium, carnation, chrysanthemum, cineraria, coleus, exacum, fuchsia, geranium, gerber, lily, lisianthus, pansy, petunia, poinsettia, primula.
Symptoms: This disease causes water-soaked tan, brown, or gray spots or streaks to appear on the flower petals, bracts, leaves, buds and stems. Spots that appear translucent or grayish in color are most common. The spots or streaks range from small to large in size. Coarse tannish-gray or cottony mold can cover the affected part in damp weather. The flowers can be
deformed, one-sided or blasted.
Conditions Favoring Disease: Flowers are especially susceptible to Botrytis blight under cool, wet conditions and high humidity. A leaf wetness period of more than four hours aids infection.
How Pathogen Survives/Disperses: The fungus overwinters in diseased flower parts, leaves, buds and other plant parts and is dispersed by wind, air movement or water splash. Handling infected plants to space, irrigate, apply pesticides or take cuttings also distributes spores.
Photo and write up provided by Syngenta Professional Products