lilac leaves yellow & curled

[lady gardener]

Hi,
I have 7 lilac bushes, ranging in age from 15+ years to new this year. Some are from nurseries; 2 are "root suckers" from other plants.
5 of them, including the new one from a nursery, are showing problems. Since about 2-3 years ago, in Spring the leaves are green & healthy looking but by this time of year the leaves have faded to yellow, and the edges of some of the leaves are curling upward and toward the center.
They are planted about 10 ft apart and mulched, and the older ones are pruned to about 6 ft tall.
They all bloomed; the problems appear after the flowers die. The bark on some of the branches also has patches that looks like lichens.
Is there any hope? I would really hate to destroy them.
Thanks.

[Spirited Lady]

Hi, I have the same problem but my leaves on some of them are hollow but not much yellow and really brittle. Did you get a response on what might be the problem?

[lady gardener]

Hi,
Sorry, but I haven't gotten any information. I've spent several hours searching the Web, and still have no idea if it's a fungus, soil deficiency, too much moisture, or a total disaster!
I've also contacted my local Cooperative Extension office, and they also had no idea. I'm stumped, and really don't want to lose all my bushes, but am at the point where I may cut down the 2 worst ones and see if any new/healthy shoots come up next year.