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Lilac blight #877661

Asked July 17, 2024, 3:20 PM EDT

Almost all the lilacs in the area have the same problem and this year is particularly bad with the wet spring. If we pull out the lilacs bit by bit (300 x 10-15 feet wide hedge) are other shrubs affected by it? Looking for replacements as we go.

Ramsey County Minnesota

Expert Response

Good Morning Judy, 

Thank you for contacting the U of M Extension Service.

Please click on the following link from the U of M Extension Yard and Garden website:

https://extension.umn.edu/plant-diseases/leaf-spot-diseases-trees-and-shrubs#bacterial-leaf-spots-and-blight-1156513

If you scroll down to bacterial blight, it discusses lilacs.

This also refers to the "managing leaf spot diseases" above. With the cool and wet weather we've had this spring, many lilacs are experiencing blight.

Leaf spot diseases can appear on most any deciduous shrub. Please review the following link about renewal pruning: https://extension.umn.edu/planting-and-growing-guides/pruning-trees-and-shrubs#hedges-and-shrubs-1336763

Rather than replace the lilacs, you could do a hard renewal pruning. This information states: 

This pruning technique works best for shrubs such as overgrown spirea, forsythia, cane-growth viburnums, honeysuckle and any other multiple stemmed shrubs that are otherwise healthy. Within one growing season, these shrubs will look like new plantings, full and natural shaped.

Here is another link about selecting shrubs:https://extension.umn.edu/find-plants/trees-and-shrubs

Good Luck!

Maureen Graber Replied July 18, 2024, 8:50 AM EDT

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