Kimberly, Idaho
June 30, 2005
Tall weeds towering over late-season sugarbeets have long
been a frustration to Idaho's growers. With hoeing crews
hard to find and harder to pay for and with over-the-top
herbicide sprays offering underwhelming control, growers
have been short of options for battling the yield-stealing
invaders.
For the fourth year in a row,
University of Idaho weed
scientist Don Morishita is testing an innovative application
method that may help growers protect their crops from
statuesque plants of kochia, common lambsquarters and
redroot pigweed. Morishita's research-sized
wiper-applicator-similar to tools used in other states and
other crops-is a carpeted, continually turning tube that he
pulls through the field behind a tractor. When Morishita and
his research team spray a mixture of Roundup and foaming
agent onto this carpeted tube and touch the resulting lather
to the tops of the targeted weeds, the results are
encouraging.
Monsanto has already labeled this application method for
Roundup, in part because of data provided to the firm by
Morishita and Stacey Camp, agronomist for Amalgamated Sugar
Co., LLC.
Morishita will repeat the
trials in early and late July at the university's Kimberly
Research and Extension Center using several different
concentrations of Roundup and other herbicides. In 2003, the
wiper-applicator was roughly as effective as hand-weeding in
protecting sugar yields, resulting in about three times as
many tons of sugar per acre as untreated "check" plots. In
2004, weed control with the wiper-applicator was 96 percent
for kochia, 81 percent for common lambsquarters and 76
percent for redroot pigweed. That compares with 99 percent,
94 percent and 86 percent for hand-weeding and is fairly
consistent with results from previous years.
By comparison, control using
the standard approach-one pre-emergence herbicide, two
post-emergence herbicides and no late-season herbicides-is
typically about 68 percent, 71 percent and 81 percent,
respectively, for the three weeds.
Morishita cautions growers to
be "really careful" when using wiper-applicators because of
the possibility of crop injury. "Any Roundup that gets on
the crop is going to affect it," he says. To minimize the
risk, he tested the herbicide at 25 percent, 37.5 percent
and 50 percent concentrations and found that the 25 percent
concentration worked as well as the higher rates.
"It's more important to
control weeds early in the season than later in the season,"
Morishita says, "but when you aren't able to get good
early-season control, then this is something to use. A lot
of growers have tried it and are really happy with the way
it has turned out for them."
Morishita is also evaluating
over-the-top mowing at the request of several innovative
growers who have already given it a try. He says mowing
even one time using a gas-powered hedge trimmer
significantly improved sugar yields in his research field.
His once-mowed plots produced 21 tons of sugar per acre
compared with 13 tons for the check plots and 24 tons for
hand-weeded plots. Morishita will repeat those trials this
year, too.
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