Nearly 200 farmers and other agricultural industry representatives attended the annual field day at the Northeast Research Station
in St. Joseph, La., on June 14, 2006. The half-day program featured stops at 10 field locations where LSU AgCenter scientists explained their research with row crops.
One topic that has generated interest is the growing resistance of weeds to glyphosate, a popular nonselective herbicide that can kill any plant it contacts. Farmers are finding plants in their fields that have survived glyphosate treatment. When they come across these plants, LSU AgCenter researcher Donnie Miller collects the seeds from the plants and grows them to see if they produce plants resistant to the herbicide.
Along those same lines, researchers are evaluating Roundup Ready volunteer cotton and soybeans, which are plants that grew from seeds left in the field following the previous year’s harvest. These seeds are from plants that have been developed to be resistant to glyphosate so that herbicide could be used to control weeds in those crops.
Researchers consider soybean plants in cotton fields and cotton plants in soybean fields as weeds. Because both kinds of plants are broadleaf, most herbicides that would kill the "weed" also kill would the crop plant. But because these descendants of Roundup Ready plants also would be resistant to glyphosate, another tactic has to be used to manage the "weed."
Farmers have to control these glyphosate-resistant plants early, Miller said.
"They can be a tough weed once they get going," he said.
Volunteer cotton also can be a host to boll weevils, and volunteer soybeans can harbor Asian soybean rust – if those plants are not eliminated.
While the boll weevil eradication program has been making progress in eliminating the insect pest from Louisiana cotton fields, Asian soybean rust is a disease that’s a looming threat to Louisiana soybean fields.
Although the fungus that causes the rust has been identified in limited areas of Louisiana the past two falls, it hasn’t appeared in commercial fields early enough in a season to cause crop damage.
Also at the field day, LSU AgCenter entomologist Ralph Bagwell talked about tarnished plant bug and aphid control in cotton.
He said the tarnished plant bug is the No. 1 insect problem in cotton in Louisiana. He recommended alternating insecticides, using higher volumes of water in insecticide applications and selecting sprayer tips that provide extensive coverage of the material on plant leaves. (This article was published in the summer 2006 issue of Louisiana Agriculture.)