Disease in Forsythia bushes
A couple of weeks ago I asked about my forsythia bushes, which have a number of clusters of dying leaves. Someone suggested it might be Sclerotinia. I looked up Sclerotinia, and my forsythia doesn't have the fuzzy growths pictured. I followed the advice to cut branches way back and wipe blade with alcohol between cuts, anyway. I couldn't finish that day, and when I went back to cut more a week or so later, I noticed that many of the leaves appeared to have small lumps inside the leaves. I also noticed a beetle clinging to one leaf, and many small flying insects around the leaves. Does this information help you to identify the problem? Do you still advise cutting the forsythia back to the ground? Thanks.
Forsythia can be subject to several fungal diseases. The insects that you are noticing may be incidental and not be causing damage. Please send us photos so we can see what you are referring to. Send photos of the whole shrub and photos of the affected foliage. Place several branches with foliage about 12-24” long on a piece of white typing paper.