Lilac dying

Question: I have a question regarding my 20+ year old lilac bush. For the first time, it appears to be dying. The leaves are turning brown and falling off. This probably started about a month ago, So end of July. I am located in metro Detroit, and have had the same thing happen to other friends in the area with their lilac bushes. We have had adequate rainfall, so I don’t believe the issue is too little or too much water. I have attached two photos for help identifying the problem. I’d like advice on what I can do to keep the bush alive. Thank you!

responder: Thank you for your question!   Laura S.      Michigan State University Extension Advanced Master Gardener Volunteer You may also contact the toll free MSU Extension lawn and garden hotline at 1-888-678-3464 with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources. Replied August 23, 2024, 5:53 PM EDT
response: Hello Donna The lilac is not dying, but has a fungal disease. It is very likely to leaf out normally next year. We have had a large number of questions like yours on lilac this year. Conditions have been ideal( humid, wet, warm) for leaf spot diseases on lilac.   It is too late to apply anything to the plant this year. What you can do now is keep it watered during dry times. Redirect sprinklers, or water early in the day, so leaves are kept dry or will be dried quickly in the sun. Rake up all fallen debris this fall to minimize overwintering pathogens.  Next spring as buds begin to open you can treat with preventative fungicide spray, applied according to the label. Repeat at intervals stated on the label while wet spring weather is present. You can stop once leaves are mature and full sized. Fungicides labeled for lilacs are listed in the bulletins below.  There are bulletins below on leaf diseases with descriptions and pictures. You may compare these to what you are seeing:  https://extension.oregonstate.edu/news/how-recognize-treat-avoid-lilac-bacterial-blight  https://hnr.k-state.edu/extension/horticulture-resource-center/common-pest-problems/documents/Lilac_Pseudocercospora_Leaf_Spot.pdf https://lancaster.unl.edu/hort/articles/2005/prunelilacs.shtml To get an exact identification of which fungi are affecting your plant consider submitting samples to the MSU Plant and Pest Diagnostic lab. There is a modest fee for the service. https://www.canr.msu.edu/pestid/ A 3 stage “rejuvenation pruning" may be helpful to get some new fresh growth, and properly thins the shrub to encourage air circulation and quicker drying of leaves https://lancaster.unl.edu/rejuvenating-older-lilacs

responder: The Question Asker Replied August 23, 2024, 6:00 PM EDT
response: Thank you so much for your quick response! I’ll heed your advice. On Fri, Aug 23, 2024 at 5:53 PM Ask Extension <<personal data hidden>> wrote:

responder: Thank you for your question!   Laura S.      Michigan State University Extension Advanced Master Gardener Volunteer You may also contact the toll free MSU Extension lawn and garden hotline at 1-888-678-3464 with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources. Replied August 23, 2024, 6:04 PM EDT
response: You are very welcome. Just remember, any pruning you do this winter or early next spring will remove those potential flowers. But, doing 1/3 of shrub at a time you will still get 2/3 of your flowers.