From the office of Linda Perrine, of the Becker County U of M Extension, responded to the flurry of calls and questions about the state of the Lilac Bushes in DL. Yesterday, she sent out an email to address the concerns: “ Questions have arisen regarding the poor appearance of lilac bushes in our area this year. Leaves are turning brown or black and falling off, it appears as if entire branches are dying.
In many cases, the term “blight” is applied and this generally means discoloration and dying of the leaves which is an apt description of what is going on. In lilacs, this can be caused by fungus or bacteria. The wet weather we have endured this spring and summer is a contributing cause.
Whether caused by fungus or bacteria, the first step in treatment is to trim out dead or dying areas of the plant. The trimmed leaves and stems should be removed from the area. Secondly, one should realize that lilacs do not do well in wet soil, hence overwatering should be avoided.
Some advocate moving plants to higher ground. Once the disease has started, there is no fungicide or antibacterial that can address the issue. As bad as the plants may look, there is a reasonable chance that it will emerge next spring and be just fine after aggressive pruning this late summer.
If the decision is made to use antifungal preparation, Remember, this is preventive, not curative and the directions on any product should be followed closely.
For more information go to: https://extension.umn.edu/trees-and-shrubs/lilacs