Pseudocercospora on my lilac ? - Ask Extension
First photo….My lilac has what looks like this fungus. Not sure how to help it. It is on one side and I removed the leaves that were brownest. It is...
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Pseudocercospora on my lilac ? #770719
Asked September 04, 2021, 2:00 PM EDT
First photo….My lilac has what looks like this fungus. Not sure how to help it. It is on one side and I removed the leaves that were brownest. It is a Katherine Havameyer so? Second photo is a nearby lilac. Third photo is a miss Kim lilac, it is about 15 feet away. What do you advise. Thank you
Lucas County Ohio
Expert Response
I do not know where you live but here in Cuyahoga County, it has been a VERY challenging year for many plants like lilacs and phlox because of powdery mildew and all the fungi which thrive in very humid weather. I am surprised that you could diagnose but could not find two good articles from Iowa State and one from Illinois for the answer to your question but I am glad to give them to you:
1. https://hortnews.extension.iastate.edu/lilac-pseudocercospora-leaf-spot
2. https://hortnews.extension.iastate.edu/2021/08/summer-foliar-lilac-diseases
3. https://extension.illinois.edu/blogs/good-growing/2021-08-05-whats-wrong-my-lilac-summer-foliar-diseases-lilac along with the admonition that you always want to go to websites that end in .edu, .gov, or .org or those of arboreta and botanical gardens for reliable, research-based information. If you want proof positive that it IS the fungus, you can send a sample to OSU. DON'T GUESS, SEND SAMPLES TO THE CWEPPDC! Did you know that Ohio State University Extension has a clinic that can help you determine what is ailing your plants and crops? The C. Wayne Ellet Plant and Pest Diagnostic Clinic (CWEPPDC) is a diagnostic facility specializing in the identification of plant diseases, plant health issues, and insect-related problems. The Clinic offers a broad spectrum of low cost testing for residential and commercial clients to identify pests and cultural/environmental related plant health issues. Experienced diagnosticians collaborate with specialists in plant pathology, entomology, and horticulture and crop science. The CWEPPDC is able to provide diagnostic and support services utilizing the latest in research and education that only a large academic university can provide. The clinic serves a wide variety of clientele. From greenhouse growers, farmers, arborists, nursery producers, landscape managers, pest control operators, to fruit and vegetable growers, the CWEPPDC can help. Clients are empowered with diagnostic results and educational materials to be able to understand the problem and to be able to implement appropriate management measures.
Scrupulous care to rid the garden of those infected leaves so they don't spread the fungus when water splashes up onto the leaves and next year can be done right now. IF there is anything to increase air movement between plants will also help as will planting in full sun. Best of all is to purchase plants that are fungus-resistant.
How frustrating it is to have such wonderful plants look so ugly. Perhaps next year will be dryer, you can apply some pre-emergents and all will be well. Certainly, that is what I hope for you.
1. https://hortnews.extension.iastate.edu/lilac-pseudocercospora-leaf-spot
2. https://hortnews.extension.iastate.edu/2021/08/summer-foliar-lilac-diseases
3. https://extension.illinois.edu/blogs/good-growing/2021-08-05-whats-wrong-my-lilac-summer-foliar-diseases-lilac along with the admonition that you always want to go to websites that end in .edu, .gov, or .org or those of arboreta and botanical gardens for reliable, research-based information. If you want proof positive that it IS the fungus, you can send a sample to OSU. DON'T GUESS, SEND SAMPLES TO THE CWEPPDC! Did you know that Ohio State University Extension has a clinic that can help you determine what is ailing your plants and crops? The C. Wayne Ellet Plant and Pest Diagnostic Clinic (CWEPPDC) is a diagnostic facility specializing in the identification of plant diseases, plant health issues, and insect-related problems. The Clinic offers a broad spectrum of low cost testing for residential and commercial clients to identify pests and cultural/environmental related plant health issues. Experienced diagnosticians collaborate with specialists in plant pathology, entomology, and horticulture and crop science. The CWEPPDC is able to provide diagnostic and support services utilizing the latest in research and education that only a large academic university can provide. The clinic serves a wide variety of clientele. From greenhouse growers, farmers, arborists, nursery producers, landscape managers, pest control operators, to fruit and vegetable growers, the CWEPPDC can help. Clients are empowered with diagnostic results and educational materials to be able to understand the problem and to be able to implement appropriate management measures.
Scrupulous care to rid the garden of those infected leaves so they don't spread the fungus when water splashes up onto the leaves and next year can be done right now. IF there is anything to increase air movement between plants will also help as will planting in full sun. Best of all is to purchase plants that are fungus-resistant.
How frustrating it is to have such wonderful plants look so ugly. Perhaps next year will be dryer, you can apply some pre-emergents and all will be well. Certainly, that is what I hope for you.
