Lilac borer? - Ask Extension
A mature lilac in my yard started to suffer, so we decided to cut it down and start over with it... Originally we suspected some sort of fungal infect...
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Lilac borer? #824620
Asked April 05, 2023, 6:44 PM EDT
A mature lilac in my yard started to suffer, so we decided to cut it down and start over with it... Originally we suspected some sort of fungal infection. Upon cutting down the limbs and taking a closer look, I saw several exit holes, peeled the bark, and found extensive damage from some sort of insect. I was not able to find any actual live insect, just the remnants/damage. Wondering what this might be?
Multnomah County Oregon
Expert Response
Thank you for your question, Jonathan. I believe that you are correct. Here is information about this pest and its management: http://pnwhandbooks.stage.extension.oregonstate.edu/insect/hort/landscape/hosts-pests-landscape-plants/lilac-syringa-ash-borer
I hope this is helpful. Good luck!
I hope this is helpful. Good luck!
Any idea when these typically emerge? I have the wood stacked in the yard and am out of town til may 8. I wonder whether a lure/trap would be sufficient if places among the wood pile, or whether I need to move the wood somewhere off-site instead?
The first article to which I referred you indicates they emerge in the spring. This article explains how to place and identify them in the pheromone trap: https://plant-pest-advisory.rutgers.edu/identifying-clearwing-moth-borers-in-pheromone-traps/
Keeping the wood on your property, with no monitoring or action will insure they will continue to use the wood as habitat, and likely spread to any healthy lilacs remaining. Please read the first article's "Management-cultural control" section. Were it I, I would move them off-site or burn them.
Keeping the wood on your property, with no monitoring or action will insure they will continue to use the wood as habitat, and likely spread to any healthy lilacs remaining. Please read the first article's "Management-cultural control" section. Were it I, I would move them off-site or burn them.
Thanks, will make note of your recommendation. I asked about timing because the article mentioned it depends on location, and I hoped maybe you had specific-to-willamette valley info perhaps?
I'm getting tired of borers: first they wreaked havoc on my currants, and now another species took out the lilac!
I appreciate the help and info, thank you again!
Jonathan: we don't have any guides to "when is spring this year?" data. One source (Kansas State Extension) indicates they do not fly until temperatures reach 70 degrees. https://blogs.k-state.edu/kansasbugs/tag/lilac-borer/#:~:text=Ash%2FLilac%20Borer%20Activity&text=Again%2C%20as%20can%20be%20seen,fly%20at%20temperatures%20below%2070 Just defining "normal" has become a challenge in light of climate change. Best I can do.
