Possible blight on Japanese Lilac Tree in Golden, CO - Ask Extension
I have a Japanese Lilac tree on my property in Golden, CO. The tree was planted last year by a landscape contractor. This year, I noticed what appears...
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Possible blight on Japanese Lilac Tree in Golden, CO #868278
Asked May 13, 2024, 6:02 PM EDT
I have a Japanese Lilac tree on my property in Golden, CO. The tree was planted last year by a landscape contractor. This year, I noticed what appears to be blight on some of the leaves (see attached photos). After a quick Google search, it looks like there can be multiple causes with various potential treatments. If anyone could provide any guidance on what I should do for my tree, I would greatly appreciate it. Thanks!
Jefferson County Colorado
Expert Response
Hello there and thank you for using Ask Extension.
Sorry to hear about you lilac. It does appear to have bacterial blight.
I am unable to rule out that it is an environmental problem like freeze damage. If the affected areas are located in random areas throughout the tree, then it is probably the bacterial blight. If the affected areas are in some sort of "uniform pattern" (ex. top of tree only, one side of tree only, exterior leaves only, entire tree), then the problem is not likely a disease. It is most likely a response to some weather event like a freeze.
If you still think it is bacterial blight, the prescribed recommendation is to prune out the diseased branches. Here is some information from K-State describing the disease and how to manage it. https://hnr.k-state.edu/extension/horticulture-resource-center/common-pest-problems/documents/Pseudomonas%20Blight%20of%20Trees%20and%20Shrubs.pdf
Based upon your photo, a large portion of your lilac appears to be affected. If you have to prune out more than 40% of the lilac, it will have difficulty surviving. Since, the plant was just planted last year, you may want to contact the landscaper. Most contractors will guarantee their plants for one year. You may be able to get a free replacement.
I hope this helps. Let us know if you have further questions.
Sorry to hear about you lilac. It does appear to have bacterial blight.
I am unable to rule out that it is an environmental problem like freeze damage. If the affected areas are located in random areas throughout the tree, then it is probably the bacterial blight. If the affected areas are in some sort of "uniform pattern" (ex. top of tree only, one side of tree only, exterior leaves only, entire tree), then the problem is not likely a disease. It is most likely a response to some weather event like a freeze.
If you still think it is bacterial blight, the prescribed recommendation is to prune out the diseased branches. Here is some information from K-State describing the disease and how to manage it. https://hnr.k-state.edu/extension/horticulture-resource-center/common-pest-problems/documents/Pseudomonas%20Blight%20of%20Trees%20and%20Shrubs.pdf
Based upon your photo, a large portion of your lilac appears to be affected. If you have to prune out more than 40% of the lilac, it will have difficulty surviving. Since, the plant was just planted last year, you may want to contact the landscaper. Most contractors will guarantee their plants for one year. You may be able to get a free replacement.
I hope this helps. Let us know if you have further questions.
