Knowledgebase

Lilacs with brown leaves #913900

Asked August 13, 2025, 2:11 PM EDT

Hello, In 2021, one of your team members walked me through the process of full rejuvenation of my lilacs that had developed brown leaves due to a fungus. The bushes all came bak nicely and this year we started to see new blooms! Unfortunately, the brown leaves/fungus has recently reappeared.... maybe due to the extra wet season??? I recall in previous communication there was mention of the use of fungicide to attack this issue. Could you please let me know what the product is, and what the application process should be? Thanks again! Joe Ghilardi

Hennepin County Minnesota

Expert Response


Last year we saw a lot of fungal disease on common lilacs. They just turned brown and dried up quickly. 

The best thing you can do is good clean up around them. Rake up the leaves and put them in the trash or commercial compost. Do not mow or mulch them or leave them on the ground. This will help your lilacs next year. 

The advice you got in 2020 was correct and it helped your lilacs do well for several years. Now you want to help keep it healthy with good clean up.

The video below provides a good understanding of the issue which is new to Minnesota. 

Fungicides don’t work well once you see the fungus. The problem is already too far along. You are correct that our humid spring weather along with moderate temps create the ideal environment for fungi. 

Deb Reierson Replied August 13, 2025, 4:32 PM EDT

Loading ...