In the News - October 2009
Pigweed causing farmers to rethink farming methods
LITTLE ROCK - Ken Smith, Ph.D., weed specialist with the University of
Arkansas, Division of Agriculture, says producers have lost this year’s battle
against nature’s forces, whether through heavy rains at planting and harvest or
through the infestation of glyphosate resistant pigweed.
Pigweed poses a major threat because of its rapid growth rate -- more than an
inch daily -- and the proliferation that results from a single plant producing
250,000 seeds. It can easily top eight-feet in height, with stalks as thick as
baseball bats at its base.
Palmer pigweed has the potential of causing catastrophic damage if it
continues to spread since no new herbicide is expected to be available in the
near future. It was found at some level in 750,000 acres in Arkansas this year.
"Yields will be reduced, and many of our farmers are asking what to do for
next year," Smith says. "We know we’ve lost this year, but we can think and plan
for next year."
While standing in a soybean test plot, Smith says he has found some workable
solutions for controlling glyphosate resistant pigweed in soybeans next season.
In one half of the study, preemergence herbicides were applied, while the other
half received post-emergence treatments.
"The half that got preemerge is clean," Smith says, "it really does not
matter which pre-emergence we use, it could be Prefix, it could be Authority
MTZ, it could be Valor, but in this study and others in other locations, the
side that received pre-emergence applications are clean."
On the clean side, a residual herbicide was applied up front, followed later
with Roundup, followed again by Roundup plus Dual applied over the top. When
herbicides were applied post-weed emergence on the other side of the study, a
weed infested field resulted even when many of the same chemicals were applied.
"I think that this is a really, really important point for us next year in
our production practices to consider the importance of pre-emerge weed control
in soybeans in our glyphosate resistant pigweed areas," says Smith.
Smith is optimistic the lessons learned this year combating Palmer pigweed,
the fifth glyphosate-resistant weed species to be documented in Arkansas, will
prove beneficial with the 2010 soybean crop if producers plan ahead.
Producers should take note of their fields now, looking for pigweed and other
weeds, and keeping records of infestations and when they treated their fields.
"It is important to record this information before harvest because it will
all be erased in the field after harvest," Smith recommends.
Smith is confident Arkansas farmers will adapt, just as they have in the
past. And that means preserving herbicides, especially glyphosate, in a well
balanced crop management program built around residual herbicides to extend weed
control between applications.
"If applied properly and if Mother Nature smiles on us, the answer to pigweed
is more manageable than we may think," Smith said.
For more information, visit
www.uaex.edu and select soybean podcasts. The
Arkansas Cooperative Extension Service, part of the University of Arkansas
Division of Agriculture, offers its programs to all eligible persons regardless
of race, color, national origin, religion, gender, age, disability, marital or
veteran status, or any other legally protected status, and is an Affirmative
Action/Equal Opportunity Employer.
October 16, 2009
By Larry Fugate
U of A Division of Agriculture
Media Contact: Elizabeth Fortune
Extension Communications Specialist
U of A Division of Agriculture
Cooperative Extension Service
(501) 671-2120
efortune@uaex.edu
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