Identification of Disease on Lilacs

Asked July 30, 2020, 6:25 PM EDT

Hello there is some sort of disease affecting my lilac bushes. I’m very concerned it is Verticillium Wilt. The affected bushes are part of a row so if it is Verticillium Wilt I’m more invested in preventing the spread to unaffected bushes then I am saving the affected ones. I tried to order my photos from the worst to the least worst

Ramsey County Minnesota

1 Response

There have been reports from around the Twin Cities of lilacs failing in much the same way your has. One suggested cause is bacterial blight of lilac. The disease symptoms don't resemble Verticillium wilt. At least one Master Gardener has sent samples into the plant disease clinic for analysis. I suggest you do the same:

The third photo shows normal powdery mildew on lilacs. The other two are similar to the mystery disease I mentioned. Another possibility to consider is herbicide drift, which can cause damage somewhat like the first photo.

Here are some references: