I would not recomend injections and systemics of chemicals that are not good
to eat for animals. many animails eat parts of the hemlock tree. If these
chemicals go to the needles than they may well just be in the other editable
parts of the tree. Other than that there is a lot on pesticides he
http://home.ccil.org/~treeman/spring.html

Hemlock trees do not tolerate fragmentation. Small disturbances such as
post logging can have a great impact of hemlocks.

With respect to the adelgid of Eastern Hemlock. I believe they are a part
of the clean-up crew. Think for a minute about the following information
regarding Hemlock and decline there of. Too often the humans do nasty
things to trees and their associates. then when decline starts. they blame
it on the clean-up crew. A great example is in the Allegheny National
Forest. In sections that were logged heavily years ago they have mortality
which is blamed on drought. But wait, the wood that was removed would have
been water reservoirs for plants and animals during dry time. Now with all
their glory they are logging to address drought issues???????????? Anyway
check this out and for a moment and say its true. Maybe this explains why
Hemlocks in disturbed areas are declining.
Eastern hemlock - Tsuga canadensis
Hemlocks of sawlog size are notoriously subject to wind-shake (481), to
radial stress cracks, and, following sudden exposure, to sunscald of the
bark, and to death. These reactions may be the result of many adverse
effects associated with a changed regime of solar heat and soil moisture and
culminate in a decline often referred to as post-logging decadence. When
hemlocks are left as residual trees following partial cutting, and when they
are exposed, through road or other construction or clearing, they often die,
even when their root area is covered with understory brush (661). Eastern
hemlock is also considered to be one of the species most sensitive to sulfur
fumes from smelters (1933). An interesting type of hemlock ring-shake
follows sapsucker injury.



Reference: Hepting, George, H. July 1971 Disease of Forest and
Shade Trees of The United States US. Dept. Agric. Forest Service Handbook
Number 386 658 pages.



Sincerely,
John A. Keslick, Jr.
Arborist
http://home.ccil.org/~treeman
and www.treedictionary.com
Beware of so-called tree experts who do not understand tree biology.
Storms, fires, floods, earthquakes, and volcanic eruptions keep reminding us
that we are not the boss.