Mon Dec 10 13:36:00 EST 1990

> Contacted the Forestry Commission in the UK about my gorse.
> They said that I should spray with TRICLOPYR which is not harmeful to
> other plant life or to wildlife.  The implication is that the herbicide
> is specific to gorse or to juniper.  Surely this is incorrect?
> -------------------------------------------------------------------
> Arnold Chamove
> Massey University Psychology
> Palmerston North, New Zealand

I used GRAZON ET herbicide, manufactured by Dow Chemical, for the
control of mesquite (Prosopis gladulosa var. gladulosa) in South Texas
during my graduate work.  GRAZON ET contains Triclopyr--I believe that
ET stands for "ester Triclopyr", not extraterrestrial (-;

Several studies that I reviewed found the effectiveness of Triclopyr
to be dependent on foliar coverage.  Meyer (no relation) and Bovey (1985)
found that a mortality rate of 0-55% was acheived with mesquite after 3
years.  I think studies have also found Triclopyr to be more effective
in certain seasons.  I can't remember if early or late spring is better.

I don't believe the Triclopyr has any soil activity--that is, it will only
effect plants when applied to foliage.  And, it won't be absorbed by roots
of other plants in the area.  However, the spray can be carried by wind or
temperature inversions, and can be deposited on other plants, where it will
_definitely_ cause damage.  Dow Chemical donated the herbicide to me for
research purposes, and specifically warned me to avoid applying it near
crops in the area.  The label indicates that it is effective against a
number of given plant species.  I think GRAZON ET was developed primarily
for pasture improvement--so, it shouldn't harm grasses.  However, if I
remember correctly, it will destroy some of the broadleaf plants.

To reduce the risk of herbicide drift, I used a drift control and deposition
agent called "Orthotrol".  This helps promote even applications, and reduces
drift considerably.  Be careful with the herbicide.  It isn't the most toxic
of herbicides, but can be absorbed through the skin.  I accidently spilled
a drop of concentrate on my finger--it disappeared immediately, and left
my fingertip numb for a couple hours.


Meyer, R.E. and R.W. Bovey (1985). Response of honey mesquite (Prosopis
     glandulosa) and understory vegetation to herbicides.  Weed Science
     33: 537-43.

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