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Global Invasive Species Team listserve digest #037
Thu, 22 Jul 1999 13:26:31 -0700 (PDT)
--CONTENTS--
1. Disposing of leftover herbicide
2. Unintended tree deaths from Imazapyr
3. Research requests for starting PhD student
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1. Disposing of leftover herbicide
From: Barry Rice (bamrice(at)ucdavis.edu)
I was recently asked what should be done with herbicide mix left over
after a day of treating weeds. The folks with the U. California, Davis
weed extension service advise the following:
First, it is best to try to avoid this situation by carefully calculating
how much herbicide will be needed and mixing just that amount. If, despite
your best efforts and intentions you still have leftover mix in your
backpack sprayer or tank you must dispose of it in accordance with the
herbicide application. The best way to do this is to spray a few extra
plants so you can finish off your mix.
Although it is less desirable, you can label and store the mixture in the
same secure facility where you store concentrate, and then use it the next
time you mix the same herbicide. Since mixed herbicides generally degrade
quickly you should use it in the mix as if it were water. For example, if
you have a quart of mix left over and the mix calls for 1 ounce of
herbicide concentrate to 1 gallon of water, mix an ounce of concentrate,
the leftover quart and 3 quarts of clean water. The problem with this, of
course, is that if the original mix was still fresh you would be applying
herbicide and surfactant at a higher rate than normal.
Incidentally, when you finish a bottle of concentrate, the bottle must be
rinsed three times with clean water before being discarded in the trash.
Anticipate this and use the rinse water as part of the herbicide mix (the
diluent). The resulting herbicide mix will normally not be significantly
more concentrated than usual. Some herbicide companies and distributors
have container recycling/disposal programs that will take back empty
containers. Other things being equal, it is best give your business to
companies that offer recycling programs.
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2. Unintended tree deaths from Imazapyr
From: Dave Borneman (dborneman(at)ci.ann-arbor.mi.us)
(the following is an edited account of Imazapyr damage sent in by Dave
Borneman, from Michigan---Barry)
Although we have no experience with Arsenal, we do have experience with
its predecessor - Chopper RTU (ready to use). In winter 1995-96 we used
this for basal stump treatment on buckthorn, honeysuckle, and
tree-of-heaven. Representatives from American Cyanamid indicated that it
would work well for what we were trying to do. Initially, it seemed to
work great - no resprouting at all of the target shrubs. Ironically, we
also noticed some dead zones ("doughnuts") around the dead stumps, where
nothing else seemed to grow, but we dismissed that as being the result of
a depleted seed bank from too much shade.
A year and a half later - June 7, 1997 - one of our city lawn mower
operators pointed out to us a 150' tongue of dead grass leading down-slide
from one of our treatment areas. That alarmed us, but not as much as the
fact that nearly all of the trees in that area were also dead!! We checked
the other spots where Chopper RTU had been applied and found the same
thing. These were oaks, hickories, cherries, elms, etc., some as large as
20" dbh. We were mortified! We contacted American Cyanamid whose reps
visited our site and confirmed that it was the work of Chopper RTU, but
pointed out that the labels says there is the potential for some
collateral damage to trees with roots in the area. That's apparently what
happened - the product was taken in by the cut stem, transferred to the
soil, and was picked up by nearby trees. We checked weather records, and
there was no rainfall in the next few days following application. Whatever
the mechanism, the dead trees numbered in the hundreds - all in city
parks, most in very visible areas.
I'm told that the highest recommended concentration of the a.i. in Arsenal
(another imazapyr formulation) is still less than the concentration found
in Chopper RTU. But, just to be safe, we no longer use Chopper, Arsenal,
or anything else that does not have a long track record of success in
ecological restoration application.
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3. Research requests for starting PhD student
From: Julie Richburg (richburg(at)forwild.umass.edu)
I am starting a PhD program at the University of Massachusetts, Amherst in
the fall of 1999. I have worked for TNC in the past and would like to do
my dissertation research on a topic of interest and importance to TNC land
managers. I have a strong interest in invasive plants (I did my master's
thesis on the effect of road salt on Phragmites abundance). Please let me
know of any burning questions you have that may lend themselves to a PhD
level research project. I would like to focus on issues in the Northeast,
although I am willing to consider other areas.