Cotton Nematode Management

To Manage Nematodes in Cotton, Add Beans

Above: At a field day, Alabama cotton farmer Richard Edgar spread the word about his research into controlling the "reniform" nematode using velvet beans. His results, a dramatic reduction in nematode populations, (see below) were publicized in Progressive Farmer magazine. Photos by John Mayne.

Growing cotton in Alabama conjures up images of family farms, rows of white bolls catching southern breezes—and, if you're a cotton farmer, nematodes. These plant-damaging pests especially thrive on continuous cotton crops. For Richard Edgar, who grew season after season of cotton, "reniform" nematodes had become a huge problem. After hearing that Auburn University researchers controlled nematodes by rotating cotton with velvet beans, Edgar received a SARE producer grant to try the rotation on his farm. Grown extensively in Alabama until the advent of commercial fertilizer in the 1940s, velvet beans fix nitrogen in the soil and crowd out weeds. Edgar set aside 10 acres divided into eight plots of 16 rows or more to test rotations of velvet bean alone, and velvet bean grown on trellises of corn and grain sorghum to keep the bean vines off the ground. The velvet beans on corn were a consistent winner, with Edgar recording nematode populations as low as five per 100 cubic centimeters of soil. When he followed with a cotton crop, the young plants were able to establish before the adult nematode populations could rebound and do any damage. Moreover, he found he could sell bean seeds for $2.50 a pound. Edgar now rotates one-third of his 440 acres out of cotton every year—most to corn, some to velvet beans on corn trellises. If the velvet bean market expands, he may find it profitable to plant more. In the meantime, Edgar still grows cotton two years out of three and applies a nematicide, but cut his treatment cost in half from a high of $21 per acre. "This project allowed us to try a number of different scenarios with reduced risk, then choose what would suit our farm situation," Edgar says.

[For more information, go to www.sare.org/projects/ and search for FS97-049]

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