One year of wheat double-cropped with soybeans did a better job of reducing reniform nematode populations in cotton as a year of corn, according to a Mississippi cotton producer

Rick Parsons, who farms 1,200 acres of cotton, 1,200 acres of soybeans and a little less than 1,000 acres of wheat in Vance, stresses that his experiment with a wheat/soybean and cotton rotation to control reniform isn't scientific. “We don't have enough years to know exactly what's going on.”

But the evidence clearly showed significant reductions in reniform nematode numbers after the wheat/soybean crop.




“But when we started picking that cotton, it just didn't turn out. We didn't pick but 900 pounds, irrigated. We should have been making 1,000 or 1,200 pounds. I couldn't figure out what happened.”

A friend suggested that Parsons may have a reniform nematode problem. The producer didn't think he did since the field had been in corn for two or the previous four years and corn is a non-host for the reniform; but he decided to check it out anyway.

In the fall of 1999, his consultant Mike Sartor, with Sartor's Ag Consulting, sampled selected 7.5-acre grids in the field. “I was shocked,” Parsons said of the results. “We had 40,000 to 60,000 reniform nematodes per pint of soil in some places and the threshold (in the fall) is 5,000.”

At that point, Parsons had made up his mind that he would have to go to two years of corn to control the reniform nematode. That's when he said he “stumbled” onto the wheat and soybean option.

The producer had already gone to a wheat/soybean rotation on the farm a couple of years earlier, but that decision was based purely on the wheat/bean crop's profitability versus corn. In 1999/2000 wheat and double-cropped soybeans were planted in the high reniform nematode field.




So what happened in the field with the reniform nematodes? For one, Parsons planted a moderately resistant soybean variety, Hyperformer 574, which Mississippi State University entomologist Gary Lawrence says played a big role in reducing nematode numbers.

The effect of the wheat/soybean crop on reniform nematodes, “needs more study,” Lawrence says. The nemtatologist plans to sample Parsons' field after the producer plants cotton in the field, to start his own database for the field. Unfortunately, research funds for a broader project on the role of wheat/soybeans were not approved this year.





“They really fluctuate in population throughout a field,” the consultant said. “On a field in Belzoni (Miss.), one part of the field showed less than 1,000 per pint of soil and another part of the field showed 30,000 per pint of soil.”



“If it's less than that, or if a farmer has to put cotton on it for economical reasons, I recommend five pounds of Temik at planting. Then we come back with two 8.5 ounce applications of Vydate CLV 7-9 days apart beginning at pinhead square.”

Vydate can also provide some control of plant bugs, which are increasing in damage about that time of the season. It's also cheaper than coming back with a sidedress application of another five pounds of Temik, another option for reniform nematode control. “When you do that, you're getting up to $35 an acre.”


