These spots may run together and rot the entire leaf. These can progress into the stem and cause the stalk to fall over. If the spots dry out, they turn brown or gray. Buds or flowers may turn brown and rot and are often covered with the diagnostic gray, fuzzy growth of the fungus. This disease shows up and spreads rapidly under cool, humid conditions especially if plants are crowded.
Control involves raking and removing any affected plant parts after the tops are killed in the fall.
It is also helpful to avoid overhead irrigation and crowding of the plants. When conditions are favorable, applications of fungicides can be made when new growth emerges in the spring. Among the compounds registered for use in Connecticut are chlorothalonil, thiophanate-methyl, iprodione, and mancozeb. Consult the label for dosage rates and safety precautions. Infected plants fail to flower or blossoms fall off before they open.