Hemlock Woolly Adelgid Questions

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Hemlock Woolly Adelgid Questions

Post by JHarkness » Sun Jul 01, 2018 10:12 am


My forest in eastern New York was first hit by HWA in the 1990s, only a small numbers of trees died. The HWA died off of all the forest trees by the early 2000s for an unknown reason, what followed in it's wake was the elongate hemlock scale, which has proved far more destructive here, I've lost dozens of hemlocks since it's arrival. Last year the HWA showed up again on a few of the forest trees. This spring I began treating for EHS using a dinotefuran insecticide with a basal bark spray application method. As far as I can tell, the EHS has largely been killed, I can't find any of it's crawlers on this years growth, however, there are HWA crawlers all over the new growth on the trees that were infested with both.

My questions to someone here who hopefully has experience treating hemlocks are: 1) How effective is dinotefuran on HWA, does it effectively kill them, or do some survive? 2) Do the HWA crawlers persist longer than the EHS crawlers when treated, my understanding is that the HWA crawlers die first and that it can take many months for the EHS to die off? 3) When the HWA crawlers are alive, can they be easily scraped off of the new growth, or can they only be scraped off when they're dead?

I'm rather concerned with this at the moment as the HWA appears to have increased it's population dramatically this spring and the trees that are infected heavily with it are continuing to look worse.

Also, I've only treated a few this spring and would like to do more this summer. Is the treatment effective with a bark application throughout the summer months as well, or is it better applied in the spring or fall?
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Larry Tucei
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Re: Hemlock Woolly Adelgid Questions

Post by Larry Tucei » Wed Sep 19, 2018 4:02 pm

Will Blozan and others can answer your question. Perhaps someone will answer your question. Larry

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