Abstract
A disease of hydrangea was found in Niigata Prefecture, Japan, 1990. Dark green to graysh brown lesions appeared on the leaf blades and blooms of the plants. A species of Botrytis was isolated from those lesions. Conidia were obvoid to ellipsoid, 1-celled, hyaline or pale brown. The optimum temperature for mycelial growth was 20-25°C on PDA medium. The fungus isolated was pathogenic to fruits of eggplant, cucumber, green pepper and tomato. The causal agent was identified as Botrytis cinerea Persoon: Fries. Gray mold of hydrangea was proposed to the disease.
