Knowledgebase

Lilac problem #879580

Asked July 31, 2024, 12:14 PM EDT

Hello. I have a very mature lilac that is losing all its leaves right now. I saw some leaf mold a couple weeks ago I’m assuming due to all the rain. Now all the leaves are browning and falling. There is new green growth appearing on many of the limbs, but it’s a bit alarming to see it dropping all its leaves so early. Is there anything I should be doing to help it. How serious is this? Any danger of losing it completely?

Hennepin County Minnesota

Expert Response

Lilac shrubs have been challenged this year. The last few years of drought, followed by our large volume of rain, has resulted in blight for many of the shrubs. If your shrub has blight clean up of the leaves and branches is important. Here is a link to information regarding blight. https://pnwhandbooks.org/plantdisease/host-disease/lilac-syringa-spp-bacterial-blights Your lilac shrub appears to have a greater amount of decline. This could indicate insect damage from a lilac borer. If this is the case you will notice borer holes on the trunk. If these are evident the borer will also be present within some branches. Below is a link with additional information regarding lilac borer. 
https://www.uidaho.edu/extension/ipm/garden-pests/arthropods/lilac-ash-borer
Amy J. Extension Master Gardener - HC Replied August 07, 2024, 10:20 PM EDT

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