Poplar hornet moth

[David Humphries]

well, that was an interesting wee site visit.

thanks for the location Peter

 

It's really good to put these things into a realistic context rather than out of a book.

 

Valuable to get a feel of a tree, its p&d & the conditions affecting it within its locality.

 

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[David Humphries]

really suprised me how many of the trees were (or are) host to the larvae.

 

Pretty much every pop within this stand are completely girdled by the exit holes (sun & shade side of the trees)

 

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[David Humphries]

I had a good listen for decay on a fair selection of the trees using a sounding hammer. Came across that there was little discernable heart decay in evidence (shame I didn't have the PD400 from work with me, to drill for resistance)

 

Having read some of the study bits on this thread, (partciularly where its noted that the larvae only tunnel just under the bark) I would tend to agree, from what I saw, that the larvae are not creating a change in the wood structure/stability concerning the cross section of the trunks. (having looked at the failed tree, the tunnels abruptly stop within a couple of inches of the surface)

 

I would think that as a consequence of the holes a pathogenic fungi has gained access, and white rotted this pops woody cells, releaving it of its lignin.

 

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[David Humphries]

As for a culprit for the failure, that's fairly difficult to ascertain.

 

I had a really good look for fruiting bodies across the site, and apart from a few sapros & a decent sized puff ball

there was precious little else there.

 

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[David Humphries]

However, having a closer look at the failure there was a broad bean sized fruiting body that needed further examination.

 

I split it open to see no forming tube layer, but a fibrous/wooly brown flesh.

 

I would lean toward this being either a Ganoderma or perhaps a Fomes.

 

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[David Humphries]

A couple of other note-worthy discoveries,

 

there was a small tree failure a little way from the main tree failure that had split out at height, just above an old woodpecker hole.

 

& just a couple trees further down the line, there was also a fair size tree that is bleeding & has a heavily declining conopy.

 

 

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[Tony Croft aka hamadryad]

psuedo plating, decline through dysfuntion of bark boring and the bleeds along with lack of fruiting bodies all indicate armillaria as the secondary pathogen, with the gano I suspect having been over run by the mellea.

 

nice documentaion David, wouldnt mind seeing this site myself

[Peter]

Good info David. The bottom line seems to be that 99% of pops in this area have borer holes, but only some of them have decay. The 2 may be linked, but you can't assume decay is present because there are holes, and the boring on its own will not cause stem breakage.

 

If this summer is hot and dry it could be a good year for the hornet moths.

[Tony Croft aka hamadryad]

its dawned on me we havent seen an image yet! so from uk moths, heres one so we know what were talking about!

 

great thread, loving it.

 

[David Humphries]

Good info David. The bottom line seems to be that 99% of pops in this area have borer holes, but only some of them have decay. The 2 may be linked, but you can't assume decay is present because there are holes, and the boring on its own will not cause stem breakage.

 

If this summer is hot and dry it could be a good year for the hornet moths.

 

Very few have decay as far as I could make out Peter.

 

Have you come across or heard of any cross road failures?

 

Would of thought that this would be common due to the sheer numbers of shelter belt/road side stands of pop in this area.

(that is of course 'if' decay is a regular side effect of the presence of the larvae)

 

 

 

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