Thank you for reaching out to ask2.extension.

There is sooo much lilac blight right now.  It is a result of the intense rains we have been having.

You can treat for lilac blight with a copper based fungicide, but it has to be done in the spring before temps get too high. If you go online to a reputable site (not Reddit or someth8ng like that), there will be suggestions to what products will work.  Be sure to read the label instructions.  you can also choose to have them sprayed by an arborist.  Be sure to check references.

For now all you can do is to cut back your lilacs and totally remove all debris from your yard.  By doing this, your lilacs will not bloom next year, but they will grow back if the blight is controlled. 

I fought this for two years on one of my bushes and ended up taking it out.  By doing that, I did save my other lilacs.

You don’t have to trim them, and let Mother Nature run it’s course, but I can’t guarantee either way that your lilacs will make it.  It’s a pretty rough disease.

I’m so sorry.  This is devastating lilacs across the state.

How do I know where to cut them? Do you have instructions?

How do I know where to cut them? Do you have instructions?

I have had a couple of professional people comment on the lilac disease.  They are suggesting to leave them be this year.  Just be sure to really clean up all the debris this fall.

For the size of your bushes I think I’d let them go and see what happens next year.