Always allow the soil to dry between each watering. Promote drying of the soil by not setting plants too close or applying too much mulch around plants. Prevent future infection by always removing and destroying diseased plants. For severe infections of Pythium or Phytophthora, the fungicide mefenoxam is available for home-owner use but will only prevent infection, not cure the disease. Apply all chemicals according to directions on the label.
Accurate diagnosis is important before any recommendation can be made.
This disease is caused by a fungus, Botrytis species, which produces a fuzzy, gray coating on the flowers and stems of many plants. When infected flowers are picked, a puff of gray spores can usually be seen. Infected areas of the plant will eventually be soft, slimy and decayed. Reduce disease development by keeping plant surfaces dry, removing aging flower blossoms and providing good air circulation. Do not overcrowd plants.