Lilac lost leaves this summer
I would like a diagnosis of what might be wrong with my lilac. It lost it's leaves ( turned brown ) but still has buds on the stems and had 2 blooms, after the initial bloom was over. I would appreciate any thing you can tell me about this. I have been mulching under the lilac could this be the problem? The lilac is white but there is a purple one behind it and it is fine? One of my neighbors said the same thing happened to theirs.
We're still suffering a terrible drought in Maryland. It has stressed plants, and stressed plants become more susceptible to diseases. It's possible your lilac has a disease known as verticillium. We can't say for sure from photos.
Water your plants well. Do not allow them to go into the winter in dry soil.
We'd recommend that you thin out some of the lilac suckers. That will allow more sunlight to reach the leaves and will also allow better air circulation.
Mulch should never be on the stems or trunks of trees and shrubs. Keep it back 3-4" from the woody stems. Mulch cools soil, which is good for lilacs, but it can harbor insects and disease problems.
If the lilac has verticillium, it can limp along for many years but will be weakened. Here is more: https://extension.umd.edu/hgic/topics/verticillium-wilt
In the bottom photo, the brown discoloration in a ring just inside the bark is the verticillium (not the brown spot in the center of the cut.)