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Lilacs dying #772675

Asked September 22, 2021, 12:12 PM EDT

In Winona County, lilac bushes are dying in large numbers. The leaves shrivel up as if it is late fall and drop and the bush dies literally. The only symptom seen has bee a slight covering of black wilt on a few of the bushes. Is this happening in other counties? Any answers? The homeowners have stated that the bushes were watered as usual. Some of the bushes are quite old - is there a longevity issue? Marianne Duffy Hohenner, Volunteer Leader for Winona County Master Gardeners

Winona County Minnesota

Expert Response

 The fungal disease Lilac Pseudocercospora leaf spot symptoms are yellowing then browning leaves, dieback. The spores of Pseudocercospora can persist for several years on plant debris (leaves, stems, dead flowers, bark. Rake up fallen leaves to help reduce the likelihood of reinfection next season. In late winter, decrease the lilac density with renewal pruning. Consistent watering will also help support the stressed plant. The first site explains lilac pruning.

https://hortnews.extension.iastate.edu/1993/2-10-1993/lilac.html

There are many reports of older lilacs suddenly wilting and dying.  Please read the following sites for other disease of lilacs.

https://extension.umn.edu/yard-and-garden-news/lilac-issues-season

https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/lilac/branchesdeaddying.html

https://extension.umn.edu/plant-diseases/gray-mold-flower-garden

They could send a sample to the plant disease clinic to determine the cause of the black wilt.

https://pdc.umn.edu/

Pat M MN master gardener and TCA Replied September 22, 2021, 1:25 PM EDT

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