Watch for Botrytis blight in annual and perennial beds. The following is more information.
Botrytis flower blight and stem canker is often present this time of year on annuals and perennials. The cooler weather and prolonged dews will favor Botrytis. Remove spent infected blossoms to prevent the fungus from moving from the flowers to leaves or stems. Stem cankers can develop on roses if old flowers are not pruned and the fungus proceeds to the stems. Look for the tan to gray fluffy fungal growth on the flowers or stems. Fungicide applications of Daconil, or thiophanate-methyl can be helpful in controlling Botrytis in the landscape along with sanitation measures.
Information from Bob Mulrooney, Extension Plant Pathologist, UD.