Thank you for reaching out to ask2.extension.

Lilacs all over the state are being affected by a lilac blight.  It is due to the weather and is spread by rain and wind, both of which we’ve had a lot of.

There is a fungicide that can be applied in the spring.  It is a copper-based fungicide that is easily available.  Please read and follow all instructions on the label.

Right now unfortunately there is not much to be done.  Clean up the debris that falls on the ground because the blight can overwinter. 

You could possibly try cutting them back, but depending on the age of the bushes, the outcome may not be what you want to see.

Try the fungicide in the spring.  Hopefully that will help your bush.

I had this a couple of years ago and let my lilac grow for two years before I finally removed it.