There are two primary diseases that impact lilacs in Nebraska, bacterial blight and powdery mildew.
Bacterial blight
In Nebraska, bacterial blight or lilac blight occurrence and severity will vary by year, lilac species, and lilac cultivar
Powdery mildew
Powdery mildew is caused by the fungus Microsphaera syringae. It is commonly observed in late summer and fall and is considered a cosmetic or unsightly disease, but impacts the health of the lilac plant to a much less extent than bacterial blight.