I guess you're referring to the use of horticultural oil sprayed on in the
Spring (Mar-April) and fall (October). We've had this problem for a year
or so, and many of my trees are too tall to spray. This article:
http://www.ces.ncsu.edu/depts/ent/no...a/note119a.htm
seems to indicate that drenching with Bayer or Merit is OK as long as it's
not done near ground water sources, streams or other runoff areas, and is
done in the spring or fall when there's enough ground moisture for the tree
to absorb the insecticide. I found today that 2 gal. of Bayer drenched 8
trees with circumferences ranging from 22-54 in. I believe another 2
gallons will take care of the 12 smaller trees I have left. I think I'm
going to go that route, despite the high cost ($90/gal) of the insecticide.
In the past spraying them has not been sufficient to keep the critters away
for more than a couple of months, and I've watched the trees go steadily
downhill. Hopefully a couple of years adelgid-free will get them to spring
back.
"Timothy" wrote in message
news
On Tue, 23 May 2006 20:16:09 -0400, Klebba wrote:
I've got 12 hemlock trees infested with woolly adelgids. The local
garden store recommended Bayer Tree & Shrub insecticide and recommended
that I drench them. After measuring the circumference of the trees, also
as they suggested, it looks like mixing one ounce of the insecticide per
inch of circumference for all those trees in a 2-gallon watering can
means
that I'll need 6 gallons of this stuff @ $90 per gallon!
My question: is drenching really necessary or can I just use the
alternate
method of spraying them at a much lower concentration and expect decent
results? I thought I might drench the ones that are too tall to reach
with the sprayer and just spray the ones I can reach.
John,
Maryland
Good day Jonh. Sorry to hear that you got the woolly adelgid. These are
rather difficult to get rid of. Before you go and purchase a bunch of
chemicals and the like, contact you local agriculture extension office.
There is a process that needs to be followed to kill them off and the kill
window has passed for you for now. Once the adelgid has the waxy fluff,
they are next to impossible to kill effectively.
maryland agriculture extension
http://extension.umd.edu/
Some information on hemlock woolly adelgids.
http://www.ces.ncsu.edu/depts/ent/no...9/note119.html
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