My purple coneflowers look funny this summer. The petals are green and deformed.
Malformed, stunted or green flowers and excessively spindly or bushy growth is usually the result of aster yellows. This phytoplasm attacks over 300 species of plants and is often seen on daisy, dianthus, gladiolus, marigold, petunia, phlox, zinnia, snapdragon, chrysanthemum, tomato, carrot, onion, lettuce, dandelions, plantain, thistles as well as purple coneflower. This tiny disease organism is carried from one plant to another in the saliva of aster leafhoppers. There is no cure for this disease and it is best to remove and destroy infected plants. Controlling the aster leafhoppers with insecticidal soap, Neem or another eco-friendly insecticide labeled for controlling leafhoppers will help limit further spread of the disease.