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Glyphosate drift damages Arkansas rice fields
(Tuesday, Sept. 9, 2003 -- CropChoice news) -- Lamar James, Farm Press Online, 08/13/03: LITTLE ROCK, Ark. As rice begins to mature, some Arkansas farmers are
finding symptoms of damage from Roundup herbicide drift. The damage
potential is great, according to Bob Scott, weed scientist with the
University of Arkansas Cooperative Extension Service. "Even low levels
of drift can cause as much as a 50 percent or more yield reduction in
rice," he said. Last year, the statewide average rice yield was a record
6,440 pounds per acre. "Arkansas has so much more rice than other states
that we seem to have the lion's share of the drift problem," Scott
noted. The problem is caused by Roundup herbicide or other products
containing glyphosate, Roundup's active ingredient, being sprayed on
soybean fields and drifting over to adjacent rice fields. It happens
when rice has reached the reproductive stage and becomes sensitive to
the herbicide. The majority of Arkansas' 2.9 million acres of soybeans
has been genetically modified to tolerate Roundup, Scott said. The 1.4
million-acre rice crop, however, has no tolerance to the herbicide.
"Farmers will begin noticing the problem when rice starts to head.
Symptoms don't show up well until then." He said the heads will be
deformed or blank, and the flag leaf, or topmost leaf, will be reduced
in length by as much as two-thirds. "Unfortunately, this year, we had a
lot of soybeans that needed to be sprayed at the same time rice was in
the reproductive stage because a lot of beans were planted later. So we
have more potential than usual for a lot of drift damage." Scott said
farmers may think they're seeing straighthead disease symptoms when
they're really seeing symptoms of Roundup or glyphosate injury. Some
farmers are surprised because they've not had straighthead before. A
glyphosate-damaged field appears to be stunted because of the small flag
leaf. With straighthead disease, the flag leaf is normal. The grain in a
glyphosate-damaged plant either never forms or is twisted, a condition
commonly called fish-hooked or parrot-beaked. "The drift problem is
pretty much all over the Arkansas Delta," Scott said. "Anywhere Roundup
Ready soybeans are grown next to rice there is the potential for drift."
The prognosis is not good. There's nothing farmers can do to correct the
damage once it's done, Scott said. He said they're left with trying to
determine how the mishap occurred and where fault lies. Scott said
glyphosate drift is becoming more of a problem, and many farmers are
becoming familiar with it because of personal experience. Jeff Branson,
Extension rice verification program coordinator, said he saw a
considerable amount of Roundup drift damage to rice last season.
"Usually there's a soybean field sitting beside every rice field. If you
get drift before it goes into the reproductive stage, you may not see
any yield reduction." He said Roundup drift from soybeans fields aren't
the only problem source. About 80 percent of Arkansas' 950,000 acres of
cotton is Roundup Ready-tolerant. Branson said, "The main thing is to
watch the wind. Most drift problems are caused by applying herbicides
when it's too windy."
Lamar James is an Extension communications specialist with the
University of Arkansas. | |
