My cosmos are all turning black and dying. It looks like they have little knats around the leaves. We live in south AL and it has been raining just about every day here for weeks. I just purchased them in a container and planted them along the fence line. One bush is doing great but the other two have black leaves. Should I cut them down? Help! Janice
Certified GKH Gardening Expert
It sounds like Aphids on your flowers and plants.
I would treat them with Neem Oil. Neem Oil is organic and safe for people, pets and Bees.
Neem Oil is an insecticide and also works as a fungicide.
You may need to repeat the treatment every 7 to 10 days.