See:
Greenhouse Plants, Ornamental - Gray Mold
Cause Botrytis cinerea, a fungus that colonizes dead, dying, and wounded plant parts. From these infections fungi can attack healthy tissues. A moist, humid environment is ideal for the pathogen's sporulation and spread. Conidia may come from sources inside and outside the greenhouse. It is found everywhere plants are grown and has a wide host range. Flower petals are most susceptible at any stage of development.
Symptoms Tan to brown blighted tissues of flower stems and leaves develop. Gray-brown spore masses may develop on dead tissues during moist conditions.
Cultural control
- Avoid overhead irrigation.
- Remove all dead and dying plant parts (particularly blossoms) on and around plants.
- Spacing plants for good air circulation.
- Plants like neutral to alkaline soils.
Chemical control
- Astun at 10 to 17 fl oz/100 gal water. Group 7 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.
Reference Minuto, A., Pensa, P., and Garibaldi, A. 2007. Sclerotinia sclerotiorum and Botrytis cinerea: two new pathogens of Iberis sempervirens. Informatore Fitopatologico 57:33-34.