Re: [SG] Hemlock Woolly Adelgid was: shady shrubs

I found horticultural oil spray effective on the one attack mine had.

Here's the URL to a factsheet on the little beasts...

http://www.ext.vt.edu/entomology/factsheets/hewoadel.html

And here is a quote on how to deal with them from an excellent post on the
subject made by Bob Stewart to Gardens-L last May.  I have not asked his
permission to quote, but he is such a nice guy, I know he won't mind ;-)
BTW, if you don't know Bob, he's and extension agent, so he knows wherefrom
he speaks.


Hemlock Woolly Adelgid Management.
(written by Bob Stewart)

       " The first step is to recognize the problem.  All hemlocks in
landscapes under your care should be inspected for woolly adelgid
infestations.  The feeding by the adelgids is a weakening process,
therefore, maintenance practices that reduce tree stress are important in
helping an infested tree coop with the problem.  Irrigation plays the
greatest role in reducing tree stress.  Trees should be watered as often as
needed during periods of drought.

   Chemical control takes on a number of different parameters.  Listed
below are the current insecticide recommendations for Hemlock Woolly
Adelgid
control.  REMEMBER.  Whenever using any chemical pesticide, always
carefully
read and follow the label directions.

   Chemical control of the hemlock woolly adelgid begins with a dormant
application of horticultural oil sometime between December and March.  It's
important that the tree be covered thoroughly with the spray.  Remember, in
order for dormant oil to be effective it must cover the adelgids.

Seasonal Insecticide Applications
    The most effective method for controlling hemlock woolly adelgid is
to thoroughly drench infested trees with an insecticide labeled for general
tree pest or specifically for the hemlock woolly adelgid: at present this
includes: horticultural oil, insecticidal soap, diazinon, fluvalinate
(Mavrik), imidacloprid (Merit), malathion, chlorpyrifos (Dursban), and
abamectin (Avid).

    Horticultural oil and insecticidal soap are highly effective in killing
adelgids, and yet they are relatively safe to the applicator, to beneficial
insects, and to the environment.  It is essential that all parts of the
infested hemlock be drenched thoroughly with insecticide. This makes
insecticide spray control on very large trees extremely difficult.

Insecticide Timing
    All life stages of the adelgid are susceptible to insecticide
sprays, however, targeting the immatures may be the best strategy.  If one
spray is to be used a late July through October time frame is best.  If two
treatments are possible, target one for the first generation of immatures
in
early to mid April, and the second in the late July through October period.
It is extremely important to thoroughly drench the trees with the
insecticide.
Because the hemlock woolly adelgid increases its population so rapidly,
it's
advisable to spray as soon as a new infestation is detected.

Systemic Insecticides
   In some cases, due to the size of the tree, or it's location, it is
not desirable to spray the tree with a chemical insecticides.  In such
situations insecticides can be injected into the truck of the tree and
moved
by the tree to the adelgid feeding sites.  Acephate (Orthene) and bidrin
are
labeled for such an application.

   The newest type of systemic insecticide application is the use of
imidacloprid (Merit) as a soil drench, where it is taken up by the plant
roots and moved to the site of adelgid feeding.

   All systemic treatments require the tree to be in active growth in
order to move the insecticide through the tree.  Adelgid control may not be
satisfactory in trees that are weakened by heavy adelgid infestations,
drought, or other stresses.

Please be careful with the use of all insecticides."


Marge Talt, zone 7 Maryland
mtalt@clark.net
Editor:  Gardening in Shade
current article: Mailorder Nurseries - On and Off Line - Seneca Hill
Perennials
http://suite101.com/welcome.cfm/222
----------
> From: Nancy Stedman <stedman@INTERPORT.NET>
> Date: Sunday, January 24, 1999 1:58 PM
>
> Are these as subject to infestation by the bug that's killing all the
> hemlocks in the northeast (can't remember spelling of the name, woolly
> something)? All my hemlocks are an inch away from death.
> Thanks,
> Nancy S.
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