I have a Tardiva hydrangea tree that has developed circular brown spots on the leaves. Some of the leaves also appear to have been chewed through, yet there is no evidence of any insects or pests on any of the leaves. Could this be a fungus of some kind, and if so, what can we do to treat/eradicate it?
Certified GKH Gardening Expert
It is highly possible that this is a fungus. There is an organic solution that treats fungus (and pests, just in case). Treat the affected with neem oil once a week for a month. Here is more information on neem oil: