goal in treating your hemlocks is to help you save as many of them as possible
for the lowest possible cost.
The most effective treatment products
The most appropriate application methods
The right balance of immediate and
Because of the proven reliability of certain systemic
chemicals, they are usually my treatments 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 the environment.
For lightly to moderately infested trees, I use a liquid
Imidacloprid product such as AmTide 2F or Dominion 2L.
For heavily infested trees, I use a product containing the
active ingredient Dinotefuran, sold as Safari 20 SG.
In both cases, I mix the product with the correct amount of water to
yield exactly the required concentration of active ingredient per ounce of
solution. Then I apply the needed amount of solution based on the
tree's size (diameter of tree trunk at breast height); larger trees require
more per inch of diameter than smaller ones.
I use any of the methods listed below to apply treatment,
making the choice according to the tree's condition, size, location, and other
factors. The one method I never use is stem injection because of the
potential for harm to the tree and the excessive cost.
Soil injection using a Kioritz soil injector
Soil drench if needed
Foliar spray using a tank sprayer (mostly for hedges)
Basal bark spray using a back-pack or hand-pump sprayer
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,
- Trees treated with Imidacloprid typically show results within 6 to 12
months (depending on their size) and have a residual protection period from
5 to 7 years.
- Safari 20 SG usually gains control over an infestation within 3 to
8 weeks and provides residual protection from 1 to 2 years.
- The treatments are 99+% effective. Success can be judged by the
- Disappearance of the old egg sacs over a period of months as the
weather beats them up
- No new bright white egg sacs (or very few on large trees) the
- New bright green tip growth
- Better foliage color and density
- Overall improved health of the tree
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