We have a row of common lilacs.
A couple of years ago, one of them almost completely died. I pruned it back, but it has been very slow to put out much new growth.
This year, I have one that had a large section die off and was rotten, and two more that the leaves are starting to show signs of wilt.
I pruned them every year right after flowering to keep the size under control. The get a little bit of powdery mildew every year, but we don't treat it.
They layout is as such:
(wilting) (wilting) (healthy) (died 2 years ago) (healthy) (dead section) (healthy) (healthy) (healthy) (healthy)
Any thoughts on what this is?
UPDATE: The decline continues and there now look to be “bite” marks any many leaves. Photos attached.
Oakland County Michigan