Lauren from Princeton, New Jersey writes
Monterey Liqui-Cop is labeled for use on lilacs for leaf spot, but not for blight. We have seen articles that recommend using copper to treat this disease, but we cannot guarantee that the product will treat this disease. We do also offer Serenade Garden Disease Control Ready to Use, which is labeled for blights and for use on lilacs.
Answer last updated on: 05/24/2016