extensive brown spot on 30 year old lilac
our big lilac is suffering with extensive brown spot from all this rain ...with the alternating heat/rain and the fact it`s mid-july,i`m afraid to do a major cut back....should I try a fungicide?...not sure what to do....I`m in between Catonsville/Ellicott city
We suspect your lilac has powdery mildew, which is very common on lilacs. Here is help with that problem: https://extension.umd.edu/hgic/topics/powdery-mildew-trees-and-shrubs
Under 'Management Strategies' you see several tactics you can use.