Abstracted from an article by Ron Smith, Farm Press
Editorial Staff
Nematode control in cotton grown in sandy soil in West
Texas is the key to improved yields. The variety Stoneville 5599 BR has shown
tolerance to the root-knot nematode,
Meloidogyne incognita, which may be taking more cotton away from
West Texas farmers than they realize, especially if they farm sandy ground.
Farmer David Warren says many of his cotton fields show only spotty infestation,
sometimes a circle that’s stunted or less vigorous than the rest of the field.
“But even with spots, yield losses can be significant.”
Warren was looking at a new product on test plots this year, Syngenta’s Avicta Complete Pak, a three-pronged combination of nematicide, insecticide and fungicide, applied as a seed treatment.
“Nematodes are all over this part of the world,” says Chuck Rowland, who farms cotton and peanuts. “We’ve been able to get by without too much yield loss with rotation and Temik. Peanuts really helped us as an excellent rotation crop.” There is a species of root-knot nematode infests peanuts but it’s different from the southern root-knot that reduces cotton yields.
Terry Wheeler, Texas A&M nematologist, says 45 percent of the area’s cotton soils have root-knot nematode infestations. Symptoms may be subtle, she says. “In sandy soils, the crop may appear uniform because nematode populations are fairly consistent throughout the field.”
“Nematode populations are dynamic. They continue to build year after year. With a peanut rotation, farmers may have no problem the following growing season, but they need to do an assay the next year, after cotton, to determine population levels. Some fields lose a significant percentage of yield to nematodes.
She says growers in a nematode-prone area may not need to pull samples every year. They pretty much know they have populations and should either rotate, use a chemical control or both. “But, even with a good rotation, growers need to monitor the population.”
Wheeler says cotton farmers need to rotate and provide some pre-plant protection. Temik has been the standard. “I’m eager to see how Avicta performs this year,” she says. One advantage of the new product is that farmers will not be tempted to cut rates and sacrifice control.
Wheeler says there are no resistant varieties. ST 5599BR is tolerant but where nematode populaqtion levels are high, use of a nematicide is also recommended. Peanuts provide the best rotation option. “Southern root-knot nematodes are capable of reproducing on milo,” she says, “and sometimes build to high levels. Most everything else in the area, including weeds, is a host.”