goal in treating your Hemlocks is to help you save as many of them as possible
from the Woolly Adelgid at the lowest possible cost.
The most appropriate and effective treatment
The right balance of immediate and
Affordable pricing based on "good neighbor"
Typical Treatment Sequence
1. Mixing the chemicals
according to label
2. Measuring the tree
breast height (dbh)
3. Filling the injector,
being careful not to spill
4. Making the correct
of soil injections
the base of the tree
5. Or applying the chemical
as a soil drench if appropriate
6. Marking the tree
to show it was treated
7. Setting up the pump
at a nearby stream/pond
8. Watering the tree to
encourage proper uptake,
- Because of the proven reliability of certain systemic chemicals, they are usually my treatment of choice.
They have been thoroughly tested and, when used according to label instructions, are safe to handle, present
no danger to pets or people on your property, and pose no significant risk
to nearby waterways, especially when applied by soil injection. For
large Hemlocks, systemic soil injection is most often the best choice.
For small Hemlocks, a foliar spray or soil drench with systemic chemicals may
be an appropriate method.
- There are non-chemical approaches such as spraying with
horticultural oils or insecticidal soaps that are sometimes used to knock
pests down temporarily, but I do not use them. They are not as reliable
because of the difficulty of reaching every branch and needle on the tree, and
they offer no residual protection. Another treatment I do not endorse
is trunk injection because of the uneven results, the potential for
injury to the tree, and the extremely high cost.
- Labs at NGCSU, UGA, and Young Harris currently have programs
for rearing predatory beetles that the scientific community fervently hopes
will ultimately provide a long-term biological control for the Hemlock
Woolly Adelgid. At present, however, beetles are generally not an
option for private landowners; they are not available from beetle labs in
Georgia, and obtaining them elsewhere is prohibitively expensive for most
homeowners. Beetles are being released at
designated test sites in our public forests to determine their effectiveness at
controlling the Woolly Adelgid and their ability to reproduce in sufficient
numbers to create a predator-prey balance. In the meantime, chemical
treatments can preserve as many Hemlocks as possible until a biological
- For lightly to moderately infested trees, Imidacloprid is a
good choice. Typically, results can be seen within 3 to 6 months, and
it provides extended effectiveness ranging from 2 to 7 years.
- For heavily infested trees, I recommend a more aggressive
chemical that is most
effective for quick knock-down of the Woolly Adelgid and gives trees a
chance to begin their recovery. Typically, results are evident within
6 to 8 weeks.
- Depending on the condition of the trees, sometimes a combination
of these two treatments or treatment in two consecutive years gives best results.
Early detection and treatment are SO important
for preserving the health of your Hemlocks
and minimizing the cost of treatment.
The cost is based on the number and size (diameter) of the trees, level of
infestation, difficulty of the terrain, and the chemical used. I evaluate
each situation on an individual basis, use my "good neighbor" rates, and do not
add any charge for travel.
As a general rule, one injection is required for each inch of tree diameter
at breast height. Here are some examples of figuring an estimated cost.
- Light to Moderate Infestations: The price per
injection ranges from $1.00 to $2.50. A Hemlock of 12" diameter would
generally cost between $12 and $18 to treat. Hemlocks 20" or more in diameter require a
double dose, so the cost is also double.
- Heavy Infestations: These trees require a more aggressive
treatment using a different chemical or combination of chemicals. The
price per injection ranges from $3.00 to $6.00. A Hemlock
of 12" in diameter would cost between $36 and $72 to treat. Hemlocks 18" or
more in diameter require a higher dosage, and the cost increases proportionately.
- In order to improve the health and viability of treated Hemlocks,
it is advisable to thin or cut out undesirable understory Hemlocks that
compete for resources and attract the Woolly Adelgid. I can help you
- If you'd like to plant additional Hemlocks to enhance the
aesthetics of your landscape and increase the value of your property, I can
supply you with healthy Hemlock saplings grown on our own property and, if you wish,
arrange to have them planted.
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questions or comments.
Copyright © 2009 The Hemlock Doctor