Diseased walnut tree #287059 - Ask Extension

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Diseased walnut tree #287059

Asked October 26, 2015, 1:16 PM EDT

Hi, I have a walnut tree in my backyard that I believe succumbed to the walnut twig. I'm having it taken down this week, but my question is about the wood after its in the ground. Once it's on the ground, is it safe to move portions of the tree to another area of my yard or is it possible to spread the disease? The area I want to store the wood is near other trees, but not near my other walnut tree.

Washington County Oregon

Expert Response

If this was thousand cankers disease vectored by WTB, then yes there is a risk that the disease can be spread from the wood. Right now, infected beetles are likely overwintering within the cambium, and will emerge next spring ready to infest new wood. As your vicinity is likely already infected, the risk of creating a problem would increase if the wood were moved to a new area. Insecticide treatments will not be able to penetrate the wood enough to kill all the beetles. WTB will continue to attack the wood until the bark is completely unsuitable. Drying the wood in a kiln or otherwise processing it by removing the bark will prevent beetle reinvasion.

If you have a beetle sample I would appreciate if you could remit that to me. We could confirm WTB.

Nik Wiman, Orchard Crop Extension Specialist
North Willamette Research and Extension Center
15210 NE Miley Rd, Aurora, OR 97002



Nik Wiman Replied October 28, 2015, 12:29 AM EDT
Thank you for your reply. The tree came down yesterday and we have contained it in its final resting place. I have taken some pictures and procured a sample for you. Please let me know if the pictures are of interest and I will send you the sample. I have included a photo of the fungus we discovered on some of the branches.
image1jpeg
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image4jpegSimage5jpegent from my iPhone

On Oct 27, 20image6jpeg
The Question Asker Replied October 29, 2015, 2:12 PM EDT
Hi I couldn't see the photos.  Since my reply I spoke with someone that is an expert on this disease in OR. My answer hinted at this but to reiterate: you are not causing any additional risk by storing the wood at your place. While many black walnut trees have been killed, there are many uninfected trees remaining in OR. Thus, moving the wood somewhere that does not already have the insect/disease is the only real risk.




Nik Wiman Replied November 02, 2015, 11:44 AM EST

Hi,

I am in the process of splitting my walnut tree and discovered this larvae today, are you interested in a sample or are you able to identify is with a picture?

Thanks,

Angie Kidder

The Question Asker Replied November 23, 2015, 5:04 PM EST

Hi,

I am in the process of splitting my walnut tree and discovered this larvae today, are you interested in a sample or are you able to identify is with a picture?

Thanks,

Angie Kidder

The Question Asker Replied November 23, 2015, 5:04 PM EST
Hi Angie,

Great photo, I would like a physical sample but it might have to be sometime in the future as I have a lot of travel coming up and will not be available until after the holidays.

Thanks so much,
Nik
Nik Wiman Replied November 25, 2015, 7:37 PM EST

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