Imidacloprid   Edward Frank
  Jan 30, 2007 17:09 PST 


I looked over the selection of bug killers at Wal-mart today. Only two
products from Bayer had imidacloprid in them.

Bayer Advanced Garden Tree and Shrub Insect Control is a 32 oz bottle
that contains 1.47% imidacloprid. It is meant to be diluted and poured
around the base of the tree with a sprinkling can. The bottle is $18.28

I am wondering if this type of application would be effective, and what
the dilution ration should ideally be?   I understand it would be more
expensive than the generic chemical.

One thing I am wondering about is the tendency of imidacloprid to bond
with humus under hemlock trees. Could you dig through the humus layer
into the substrate and apply it there instead?

You have mentioned generic imidacloprid powder under the names ZENITH 75
75WSB, etc. Are there limits to who may sell these products or purchase

Ed Frank
RE: Imidacloprid   Will Blozan
  Jan 30, 2007 18:00 PST 


I have heard of good to excellent results from Bayer Tree and Shrub Insect
Control. The dosage is the equivalent of the highest dosage that can be
applied via the powdered version that I use in my business. It is expensive,
with one bottle treating only a 10" diameter tree. This equates to ~$1.90
per diameter inch (with tax) versus ~ $.80 per inch for the other products
you mentioned. The biggest complaint I have heard is the extraordinary
amount of water they recommend mixing the solution in. I don't quite see the
need for so much water but then again, I don't use the product myself.

In NC, anyone can buy the other products, which are a powder, at an
agricultural insecticide dealer. As long as you are not applying the product
for profit you can buy and apply without a pesticide applicator's license.

The studies I have read indicate that hemlock roots are very shallow and
will exploit the upper layers of organic material so a topical or shallow
application is best. I have seen 4.5 years+ control of HWA from one soil
drench application of imidacloprid at the median rate on the label.
Obviously there was no need to apply below the surface, although all my
applications now are just below the surface in the organic layer under the
loose duff.


RE: Imidacloprid   Doug Bidlack
  Jan 30, 2007 22:29 PST 

Ed and Will,

I think the Bayer product is what my mom is using on her White Ash
'Autumn Purple' and Black Locust 'Purple Robe' for emerald ash borers
and locust borers. The white ash was never touched, so I can't say much
except that the tree is still alive in a sea of dead ashes. The black
locust was ravaged the first year after we planted it, but it hasn't
been touched since treatment (three years now).

RE: Imidacloprid   Brandon Gallagher
  Jan 31, 2007 05:51 PST 

If you are interested in purchasing imidacloprid for HWA you can contact
me at one of the numbers below. Our company has a product, Xytect, in
both a 75WSP and 2F (liquid) formulation that is imidacloprid marketed
specifically at the tree care market. The largest tree care companies in
the country are using it exclusively and the USFS and several state FS
are using it this year. As Will said, we can sell both formulations to
private citizens as end users, however if you are going to offer
treatments as a service you will need a license. Later this spring we
will carry a Xytect Infusible which is a injectible formulation that is
applied through our new refillable M3 infuser. Check out
for more.

Brandon Gallagher Watson
Technical Support
ISA Certified Arborist MN-4086A

Rainbow Treecare Scientific Advancements
2239 Edgewood Ave S
Minneapolis, MN 55426
Re: Imidacloprid   Edward Frank
  Jan 31, 2007 17:47 PST 

Will and Brandon,

Thank you for your replies. I was curious about this particular product.
The HWA is not here yet, although it may arrive later this summer or next
year. At that time I will likely be buying stuff to treat a dozen plus
trees or so in our small lot.

Ed Frank
Re: Imidacloprid   John A. Keslick, Jr.
  Feb 01, 2007 03:30 PST 

Are we killing the good guys as well as the bad guys? For an example: Less
than 1% of the insects and fungi are harmful to humans. Think about that
when you use a product that kills everything. Trees have many associates
that address their quality of life.


John A. Keslick, Jr.
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.
Some people will buy products they do not understand and not buy books that
will give them understanding.

Re: Imidacloprid ,John
  Feb 01, 2007 05:52 PST 

I don't think your way of thinking is crazy, just different. Imidacloprid kills insects that feed on the plants that are treated. It is not a contact insecticide. It is much more friendly to the earth than systemic insecticides of the past. It has a long residual so repeated applications aren't necessary. I treated a copper beech in 2001 for wooly aphids. The population had definitely breeched the threshold, as the honeydew sounded like rain falling from the tree. With one application of Imicloprid into the soil (no non targets were affected by air) it cleared the problem up and they haven't been back. Oils and other contacts do kill everything. Using IPM methods, this seems to be the best choice. Imicloprid does not have fungicidal properties to my knowledge.

Re: Imidacloprid   Jess Riddle
  Feb 02, 2007 16:39 PST 


Killing not-target organisms is certainly unfortunately and to be
avoided where possible. However, we need to evaluate our options
against alternatives rather than against currently impossible ideals.
Yes, imidacloprid will kill organisms that feed on hemlocks in
addition to the adelgid, and if applied to the soil, some soil
organisms in a localized area. What if we don't treat the hemlocks?
The hemlocks will die and the organisms that feed exclusively on them
will have no food. The soil will be disturbed over a much broader
area; in some ways less intensively and in other ways more
intensively. If we had some way to attack the adelgids and only the
adelgids that would be wonderful. The beetles are currently the
leading hope for that solution, but we haven't yet figured out how to
get them to reduce adelgid populations to trivial levels.

RE: Hemlock and Adelgid Survey   James Smith
  Feb 02, 2007 17:10 PST 
It seems obvious even to a layman such as myself that the only effective
way to buy time is to use the most effective adelgicide in as wide an
area as is possible. Yes, some organisms will suffer in the short-term,
but the long-term effects of the extinction of the eastern and carolina
hemlock species equals the extinctions of those organisms that are tied
exclusively to those trees.

I think of our hemlocks every day. Every single day. It sickens and
depresses me to think that these trees, among which I have hiked all of
my life, will soon become extinct.

If it were possible to treat vast areas of hemlocks forests with the
effective adelgicide, what are the long-term odds of the eastern and
carolina hemlocks surviving an extinction event?