See:
Greenhouse Plants, Ornamental - Gray Mold
Cause Botrytis cinerea, a fungus. The disease may become severe when plants are crowded and growing conditions are humid. This fungus readily colonizes senescent leaves and flower parts.
Symptoms Affected parts of the plant become covered with a gray fungal growth. Flowers, leaves, and crowns may be affected. Leaf infection often occurs when withered flowers drop and adhere to the leaves. Infection of the petioles may occur at the point where they come in contact with the pot or other containers.
Cultural control
- Avoid crowding plants.
- Improve ventilation and reduce humidity.
- Avoid overhead watering.
- Remove and destroy badly affected plants or plant parts.
Chemical control Best when used with cultural controls. Tank-mix and/or alternate products from different groups with different modes of action to prevent the build-up of resistant fungi.
- Decree 50 WDG at 0.75 to 1.5 lb/100 gal water. Do not use more than two (2) sequential applications. Group 17 fungicide. 12-hr reentry.
- Mancozeb-based products can be used as mixing partners and provides some protection. Group M3 fungicides. 24-hr reentry.
- Fore 80 WP at 1.5 lb/100 gal water plus a spreader-sticker.
- Protect DF at 1 to 2 lb/100 gal water plus 2 to 4 oz spreader-sticker.
- Medallion WDG at 2 to 4 oz/100 gal water. Use with oils or adjuvants may cause plant damage. Group 12 fungicide. 12-hr reentry.
- Pageant at 12 to 18 oz/100 gal water. Do not use with organosilicone-based adjuvants. Group 7 + 11 fungicide. 12-hr reentry.
- Sil-Matrix at 1 to 4 quarts/100 gal water plus a nonionic surfactant. 4-hr reentry. O
- Spirato GHN at 2 to 4 fl oz/100 gal water. Use with oils or adjuvants may cause plant damage. Group 12 fungicide. 12-hr reentry.
- Terraguard SC at 4 to 8 fl oz/100 gal water. Group 3 fungicide. 12-hr reentry.
Biological control
- Prestop (Gliocladium catenulatum strain J1446) at 0.33 oz/5 gal water. Do not use with other products in the tank. 4-hr reentry. O
Reference Dik, A.J. and Wubben, J.P. 2007. Epidemiology of Botrytis cinerea Diseases in Greenhouses. pp 319-333. In: Elad, Y., Williamson, B., Tudzynski, P., and Delen, N. 2007. Botrytis: Biology, Pathology and Control. Springer Netherlands.