The fungus that causes Botrytis blight is commonly called the gray mold fungus. Gray mold attacks a wide variety of plants and likely causes more plant death and losses than any other single disease-causing agent. Botrytis blight can cause disease on nearly any plant grown in the home landscape, garden, and greenhouse and it is one of the most common diseases of geranium and a wide variety of ornamental plants, vegetables and fruit. The fungus causes brown rotting and blighting of affected tissues.
Use Caution While Pruning:
Tender tissues (seedlings and petals), and weakened tissues (stubs left after taking cuttings and pruning) are attacked by the fungus since the fungus needs an open wound to invade the plant. When pruning plants, a stub no longer than ½ inch should be left because longer stubs do not form callus as quickly as short stubs. The callus formation limits the fungus invasion into the cut stub.
Identifying Botrytis blight (Gray Mold):
Gray mold can be identified by the development of fuzzy grayish spore masses over the surfaces of rotted tissues. It is not unusual to observe these grayish spore masses on the rotting flowers of outdoor grown geraniums within 24 hours after it rains.
The environmental conditions which favor Botrytis blight include cool temperatures (65-70 F) and wet, humid weather. On ripe strawberry fruit the gray mold spores will germinate and invade the fruit within 3 to 5 hours during ideal temperature and moisture conditions.
Preventing Botrytis blight (Gray Mold):
Sanitation procedures are very important in control of Botrytis blight. It is important to remove and destroy dead plant parts – leaves, stems and flowers since the gray mold survives on these tissues and will provide spores to invade healthy plants. GreenCure® will provide preventative control of this disease and should be used at 1 to 2 tablespoons per gallon of water, especially after rains and cool temperatures. Obviously with vegetables, prevention is much wiser than trying to eradicate mold once it has taken hold.
Geranium leaves infected with botrytis blight