Purple Coneflower Wilting and Turning Brown
Some of my purple coneflowers are wilting, turning yellow and browning. A few stems have died. I have found scattered examples of this throughout my planting.
Stem wilt and aster yellow can cause the symptoms you describe. Control stem wilt by removing and discarding the wilted stems. Aster yellow is a phytoplasm that is carried from sick plant to healthy plants by the aster leafhopper. This insect spreads the disease from one plant to the next as it feeds. Remove infected plants as soon as the problem appears. I have had good luck containing the disease with just sanitation. Control leafhoppers with insecticidal soap, Neem or another eco-friendly insecticide to stop the spread of this disease. Fortunately the coneflowers re-seed and leave plenty of offspring to replace those you removed.