Primarily seen in greenhouse production, but can be seen in the landscape also. Cloudy humid conditions for several days favor disease development. All hydrangea species are susceptible to B. cinereae.
Small water-soaked spots can be seen on the margin of the leaves
The watersoaked regions expand to reddish brown spots
Symptoms on the margin of the leaves
Symptoms on the stem.
Burn-like patches on the leaves due to the disease.
Symptoms on a leaf.
The leaves and petals will be covered with a fuzzy gray growth of the causal fungus B. cinereae.
Severely infected plant with masses of spores which can be easily seen with a hand lens. The spores are easily moved by wind, and greenhouse practices of over-watering and handling moves the spores around the production units.
Botrytis can develop overnight under ideal environmental conditions.Cool, wet conditions favor rapid growth and reproduction of B. cinereae. The fungus can survive indefinitely in plant debris.