By Hortoculturalist Beth Hawke
at Grey Towers
attended this workshop on the
woolly adelgid, a tiny insect
about the size of the head of
a pin which has caused widespread
decline and death of hemlock trees,
from southern New England to the
Smoky Mountains. Hemlock mortality
rates of 70% to over 80% in this
region are common, with only western
and northern areas of the Appalachians,
Catskills, Great Lakes and Adirondacks
still free from the pest. The
hard winters in these areas in
recent years are the main reason
that infestation has not spread
further -- the adelgid cannot
survive sustained temperatures
of below 5 degrees Fahrenheit.
Towers Horticulturist Beth Hawke
led a discussion on how to recognize
a woolly adelgid infestation and
what landowners can do to protect
and prevent further decline of
hemlock stands, which are still
present in our region, some still
in a healthy state depending on
the specific location.
are an important component of
the forest ecosystem, comprising
about one-fourth of our forests.
This tree prevents erosion along
rivers and provides winter shelter
and food for wildlife.
woolly adelgid sucks sap from
the young twigs, causing the needles
to discolor and drop prematurely.
The loss of new shoots and needles
seriously impairs tree health,
with defoliation and tree death
occurring within several years.
attached web page was distributed,
describing the history of the
problem and showing with words
and pictures how to recognize
an infestation from the white
cottony sacs on the underside
of hemlock twigs and needles.
Also, a map was passed around
at Beth’s talk – I have a copy
– showing the extent of the infestation
up and down the Eastern Seaboard
as of 2004, with the NY State
infested area clearly including
both Delaware and Sullivan Counties.
though many of us in the Beaverkill
area so far have not seen evidence
of a woolly adelgid infestation,
Beth informs me that the map is
accurate. Once the pest is found
in one location in the county,
it is on the infested list. No
county has ever been removed once
it is listed as infested because
there are many hemlocks in those
counties and Beth cautions that
viewing from the ground does not
mean that the tree is free of
the adelgid. So once it is there
it is usually never completely
eradicated. Beth told me that
our county may not be heavily
infested yet, but there is a big
possibility that there is still
some adelgid nearby. I have heard
other reports that the pest has
been detected at Frost Valley.
So while it may not be widespread,
it should probably be considered
as in the area and a viable threat.
as the July 21 workshop made clear,
careful monitoring is the key,
together with treatment once the
pest has been located and identified.
Treatment includes use of horticultural
oil or insecticidal soap, applied
by spray from truck or backpack
tanks, or the pesticide Merit.
Unfortunately, there is no one-time
preventative treatment prior to
infestation since no treatment
effect lasts more than a year
or so and must be re-applied annually.
So frequent monitoring, especially
in the spring and fall, is the
only answer with treatment recommended
only when the pest is discovered.
safest for both environment, applicator
and wild life is the horticultural
oil or soap. These treatments
only "smother" the
soft body insects (the adelgid)
leaving the other beneficial insects.
These are also safe around water
near streams and water sources
should be used only as an injection
into the trunk of the tree and
done by certified tree arborists.
For those hemlocks away from a
direct water source, the "over
the counter" Merit
applied as soil drenching around
the tree could work. Merit, in
tests, does not appear not to
travel far in the soil. So it
is a safe treatment, but remember
that it is a pesticide.
most expensive treatment is the
Merit trunk injection, which costs
from $200 to $300 per tree.
Hawke has kindly offered to answer
further questions, so please let
me know if any of you would like
to know more.
in addition to a link to a printable
text, you will find two links
to the US Forest Service with
more info about the Woolly Adlegid,
home | calendar | headlines & happenings | milestones | church
about us | maps | photos| stories | archives