I have several varieties of coneflowers in my garden in Delaware. The buds form fine; however, as the petals develop, they either shrivel or get eaten by something. I have sprayed with insecticide and put slug bait down but nothing seems to help. What could be causing this? It's been extremely HOT and I wondered if that could be a cause.
Certified GKH Gardening Expert
Treat the plant with neem oil. It will take care of most insect pest issues and is an effective fungicide as well. Here is an article that you may find helpful: https://www.gardeningknowhow.com/ornamental/flowers/coneflower/coneflower-problems.htm