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Edgeman
Road (Lander County Road 120 E)
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| The purpose of this
test was to experiment with various chemicals for the control of annual
and perennial grasses and weeds in an area inaccessible to blading. In this
case, the farm fence is within eight feet of the road surface. The right-of-way
had not been bladed for many years and supported a thick growth of perennial
grasses and annual weeds, mainly prickly lettuce and kochia. |
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1. Treatment. |
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In
May, 1999 Diuron was applied at the maximum rate on the label. By the next
spring there was little effect from the Diuron, so the test area was divided
in two parts and two different mixes were applied over the same area. At
one location, Arsenal herbicide was applied at the midrange rate on the
label for the target species, and on the other a mix of Oust and Karmex
herbicides were applied, also at the midrange rate on the label. The memorandum
of 4/18/00 in Attachment II includes the details of these applications. |
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2. Results. |
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As mentioned above, the treatment
with Diuron showed no effect by the following spring, presumably because
there was very little precipitation following application and through the
summer. The salt cedar tree sprayed with Arsenal was not killed. One area
was treated with the mix of Karmex and Oust, there has been little or no
plant growth through February, 2002. |
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3. Conclusion. |
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The
second treatment of this area probably masked the effect of the Diuron during
the second season. The roadside was left undisturbed the season following
treatment. Winter and spring moisture during 2000 may have washed the Diuron
off the over story and into the soil, to become effective during the 2000
growing season. April, 2000, when the second treatments were applied, may
have been too early for evidence of the first treatment to become evident.
Arsenal is not effective against salt cedar when applied early in the spring.
We know it is highly effective with fall or summer applications.
The Karmex and Oust essentially duplicated the Diuron treatment, doubling
the dosage. Karmex is another brand name for Diuron. Whether either treatment
would have done the job alone, is uncertain.
High rates of Diuron, or equivalent, is able to get through heavy growth
by being washed off the over story and into the soil, and then suppress
plant growth for up to two years. Probably fall application would be most
effective in areas that are not irrigated since winter precipitation is
more certain than spring rain or snow. |
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