Q.Is This Fungus On My Hydrangea?
I noticed these spots several weeks ago. We have catmint growing next to the hydrangeas, and the rotted catmint stems at the base grew out enough that they were touching the base of the hydrangeas. I removed all of the rotten catmint leaves, but the hydrangeas have continued to deteriorate. Is it too late to apply a fungicide? Should I wait until next spring?
Certified GKH Gardening Expert
This appears to be anthracnose. It has no cure, but can be managed. Keep the area clean, prune away all dead growth, and treat with a fungicide. This will help keep the spread at bay. This is important in fall and spring, since this is when it will start its spread again.
Since this could be one of many fungi that cause anthracnose, you may want to seek some local help. Your closest extension service will help you to test and offer specific treatments tailored to the specific diseases.
https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm
