U.S. cotton production losses to nematodes have climbed from 1% to about 5% since 1988, with the reniform nematode increasing in severity during that time, says Bill Gazaway, Auburn University Extension plant pathologist/nematologist and emeritus professor.
“Part of this increase is due to more awareness by our scientists. But most of these losses are due to the reniform nematode,” says Gazaway.
The U.S. cotton industry lost an estimated $402 million to nematodes in 2004.
“This is a significant increase, and it's one we need to be concerned about,” says Gazaway. “The root-knot is responsible for 53% of our total nematode losses while the reniform is responsible for another 41%. The remaining 6% is due to lance and other nematode species.”
Prior to the 1980s, the reniform nematode was considered a minor pest, he says. “Since then, it has spread at an alarming rate to all areas throughout the Southeast. In fact, Louisiana, Mississippi, Alabama and parts of Arkansas sustain about 80% of the damage from reniform nematodes.”
What's more alarming, he adds, is that the reniform nematode continues spreading to other states.
“Unlike the root-knot, the reniform can damage an entire field,” says Gazaway. “We've documented losses in fields up to 75% under stress conditions.”
He says there is no resistance in commercial varieties to the reniform nematode.
There are challenges for the future in improving nematode management systems, Gazaway adds.
“First we need a quick way to identify and find out the location of the culprits,” he says. “Research is being conducted with remote sensing and infrared remote control technology. In identifying the nematode itself, we're looking at methods that use carrier fungi and viruses. We're also looking at DNA analyses.”
