Lilac bacterial blight
Hello: I have 16 lilac bushes all with some amount of lbb. I have lost one entire bush, 1/3 and 1/4 of another. Can I currently spray a copper fungicide on the ones that continue to get a disease on it? If I wait until the fall after the leaves are gone, I am afraid I won't have any lilac plants left. Also, how far down on the main stem should I cut the branch back to. I know 6 to 12 inches per branch but what about the main branch? Thank you, Dawn
DeKalb County Illinois
Has lilac bacterial blight been identified by a plant disease lab? I would start with that, to be sure you have a proper identification before starting a major treatment regime. Here is a link to the U. of Illinois Plant Diagnostic Lab: http://web.extension.illinois.edu/plantclinic/ .
I'll be honest, I'm not familiar with lilac bacterial blight. It is not a common disease problem of landscape lilacs. Here are a couple of university bulletins that describe the disease and its control: