Sick lilac bush - Ask Extension
We purchased our lilac in April, 2021. It has seemed to thrive until about 2 1/2 months ago. It never bloomed this year, but spent its’ Spring looki...
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Sick lilac bush #804253
Asked August 02, 2022, 1:22 PM EDT
We purchased our lilac in April, 2021. It has seemed to thrive until about 2 1/2 months ago. It never bloomed this year, but spent its’ Spring looking great. When it started to fail, I looked on the Web and read that we should fertilize and cut away the bad branches. That didn’t work so next I cut off a branch and took it to our local hometown garden center for a recommendation. They talked me into buying a systemic bug killer that I put under the topsoil around the plant. That was about a month ago and the downturn continues. I have included pictures. The bottom growth looks very healthy.
Lane County Oregon
Expert Response
Hi and thanks for your pictures of your sad lilac bush. Since you weren't very specific about what the "decline" of your tree looked like, I'm attaching a chart that describes some lilac diseases and treatments.
https://extension.psu.edu/lilac-diseases
I'm surprised there was a bug killer recommended but I do see some white filaments on one of the pictures and they may have seen more on the branch sample you took in. The new shoots look healthy so if they can grow and survive, you may have solved the problem. If they begin to show symptoms, take some pictures at each stage of decline and we will try again to see what the issue is.
Good luck!
https://extension.psu.edu/lilac-diseases
I'm surprised there was a bug killer recommended but I do see some white filaments on one of the pictures and they may have seen more on the branch sample you took in. The new shoots look healthy so if they can grow and survive, you may have solved the problem. If they begin to show symptoms, take some pictures at each stage of decline and we will try again to see what the issue is.
Good luck!
What I failed to ask is I would like to know where I can safely prune the trunk and branches. I would like to cut away most of the trunk and certainly all the dead/dying branches, but don’t want to shock the poor thing. Please advise. Thanks!
Yes, I see the problem. Since we don't know how much of the new growth is being supported by roots from the original trunk, I would not cut it at this time. I'm attaching an article about pruning lilacs for general information, but at this time I would only cut off the dead branches.
If you want to nip the very top of the central trunk, it would be interesting to see if there is any green showing in a cross-section, proving that the trunk is still alive.
I know, it will look pretty strange for a year, but it will certainly be safer to allow the trunk to overwinter and then see what happens next spring.
Isn't gardening exciting when you get to experiment with saving a tree!
If you want to nip the very top of the central trunk, it would be interesting to see if there is any green showing in a cross-section, proving that the trunk is still alive.
I know, it will look pretty strange for a year, but it will certainly be safer to allow the trunk to overwinter and then see what happens next spring.
Isn't gardening exciting when you get to experiment with saving a tree!
Oops, forgot to attach the article:
https://extension.oregonstate.edu/news/prune-lilacs-soon-after-bloom
https://extension.oregonstate.edu/news/prune-lilacs-soon-after-bloom
Thank-you so much for this information!
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Sent: Tuesday, August 9, 2022 10:40 AM
To: trmelin <<personal data hidden>>
Subject: Re: Sick lilac bush (#0074184)
Sent: Tuesday, August 9, 2022 10:40 AM
To: trmelin <<personal data hidden>>
Subject: Re: Sick lilac bush (#0074184)
