Peanut-cotton rotations help prevent nematodes, weeds

In Southwest Farm Press

Peanuts are a good complement to cotton, especially in fields infested with cotton root knot nematodes, says Jason Woodward, Texas A&M AgriLife Extension plant pathologist at Lubbock. The microscopic pest won’t affect peanuts and the peanut root knot nematode won’t injure cotton.

He discussed the nematode factor and peanut best management practices by Skype hookup during the recent Red River Crops Conference at Altus, Okla., as well as disease issues, varieties, and market types.

“We learned in 2015 that cotton nematode infestations result in non-uniform stands, galls on the roots, poor plant growth, and inability of roots to pick up water and nutrients,” Woodward says. “On peanuts, we see similar symptoms, including chlorosis, poor growth, soil adhering to the roots, and symptoms developing on the pods.”

Test plot studies show differences between continuous cotton, cotton and grain sorghum rotation, and cotton and peanut rotation. “Cotton following peanuts had the fewest galls,” he says. “Cotton following peanuts also made significantly better yields in cotton root knot nematode-infested fields than cotton following corn.”

Weed control is an important aspect of nematode management, too, he says.  Many weeds are hosts for root knot nematodes. “Russian thistle is three times better as a host for cotton root knot nematodes than non-resistant cotton varieties. Weeds can spoil nematode control efforts.” Palmer amaranth, nutsedge, and other weeds also host root knot nematodes.

WEATHER ISSUES

Woodward says 2015 weather patterns created problems for peanuts. “Cool, wet conditions caused delayed emergence and stand issues. Some cases of low quality seed and no seed treatment also contributed to early stand problems. It is important to use high quality planting seed and a seed treatment, especially in a less-than-ideal planting environment.”

Delayed emergence was not uncommon last spring, he says. “In some cases, emergence was delayed until three to four weeks after planting. That affects uniformity and maturity of the harvested crop.”

The combination of cool, wet conditions and poor seed quality, in some cases, created stand problems. “Overall, I was happy with our seed quality,” Woodward says, “but growers need to make certain they get high quality seed.”

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