Cotton, Peanut Rotation Provides Value to Both Crops
February 15, 2024 Cotton and peanuts have long been stalwart cash crops in Georgia and Texas, and growers in both states have been rotating the two commodities for decades to help control nematodes. But the synergistic relationship between cotton and peanuts brings more to the table for growers than just lowering nematode thresholds.
As Forrest Gump might say, they go together “just like peas and carrots.”
“Fortunately, nematodes that impact peanuts — primarily the peanut root-knot nematode and to a lesser degree, the lesion nematode — will not feed on cotton,” says Bob Kemerait, University of Georgia Extension Plant Pathologist. “On the other hand, the southern root-knot and reniform nematodes found in cotton will not feed on peanuts. Rotating these two crops offers growers an opportunity to remove a host plant from the nematodes, they starve, and their population is reduced. It’s a reliable production strategy that offers many advantages I find myself reminding growers about periodically.”
Some crop advisors suggest putting peanuts on cotton ground no more than every three to five years, because peanuts bring problems like foliar diseases and underground fungi. The fungal pathogens not only defoliate the crop but also rot peanut pods and kill the plants. Peanuts can require a strict fungicide program for troublesome diseases like leaf spot and white mold (southern stem rot), with applications sometimes made every 14 days.
Using a cotton rotation helps break the cycle on these and other diseases, but there’s also tomato-spotted wilt virus in peanuts that’s controlled by a combination of practices including altering planting dates, applying an insecticide at planting, planting proper seeding rates, and selecting a resistant variety.
Peanut acreage in Georgia increased significantly after the boll weevil arrived and all but shuttered cotton production. After the long-snouted pest was eradicated in the mid-1990s, cotton acreage in the state rebounded to over one million acres and has since hovered around that number annually. Ground dedicated to peanuts now fluctuates annually between 650,000 to 800,000 acres, which allows for fields to be rotated out of peanuts for one to two years into other crops like cotton.
“Nematodes may not reduce cotton yields in every field across our state, but they can appear in any field any given year whether it’s the reniform, root-knot, sting, or even the Columbia lance nematode in the eastern part of Georgia,” says Camp Hand, University of Georgia Extension Cotton Specialist. “The nematode we fight most in cotton is the southern root-knot, and we continue advising growers to rotate their cotton fields to peanuts periodically.”
Some cotton growers put out either a liquid or granular nematicide in-furrow at planting. Nearly 30% are using Ag Logic (formerly known as Temik) to slow down nematodes and thrips. Telone II is the go-to option when nematode populations are well above threshold or to battle Fusarium wilt in cotton caused by a fungus that partners with nematodes that can damage cotton. Newer cotton varieties that offer nematode resistance are also gaining in popularity in areas with a history of damaging infestations.
Hand looks at cotton and peanuts like partners in crime — you can’t have one without the other. He believes that rotation is why Georgia is able to stay committed to cotton.
“We need a rotation that can handle dryland production,” explains Hand. “Cotton and peanuts are our only options. If we planted soybeans on this beach sand, there’s no telling what our yields would be. But in a bad year, we might not make a bushel an acre.”
Peanuts don’t require a lot of fertilizer, and because they are a legume, they fix nitrogen back into the soil.
“We make use of that fixed nitrogen in subsequent cotton crops, though we might not account for it all the time,” says Scott Monfort, University of Georgia Extension Peanut Agronomist. “Peanuts are a great scavenger of nutrients too. If the previous crop is fertilized adequately, peanuts do not require phosphorus and potassium fertilization. About 50% of our peanut acreage is deep turned at planting, so we’re redistributing a lot of nutrients back through the soil profile and also burying disease inoculum and weed seed. There’s always a nominal amount of calcium left in the soil each year that will be taken up by cotton when the field is rotated from peanuts.
“There’s a nice give and take in that rotation, yet another reason why cotton and peanuts complement each other well.”
Weed Control Synergies In Texas
As the largest cotton-producing state, savvy cotton growers in Texas understand the value of rotating cotton with peanuts. Depending on prices and contracts, peanuts cover 170,000 to 200,000 acres across the state.
“While many of our cotton and peanut growers understand the benefit of nematode control this rotation brings, it also brings another lesser-known benefit — weed control,” says Emi Kimura, Texas A&M AgriLife Extension Agronomist and Extension Peanut Specialist. “I remind growers often about the value peanuts bring to weed control in cotton, because the herbicides used in peanuts fall within a different mode of action and that helps preserve those cotton herbicide chemistries.”
Monocultured cotton is hard on soil health. Cotton pulls a lot of N, P and K early in the season to set bolls. Not all Texas cotton growers have the agronomic option of growing peanuts.
“Because of clay soils in many parts of our state, some growers have to rotate with wheat, sorghum, or even corn if they have reliable irrigation,” says Reagan Noland, Texas A&M AgriLife Extension Associate Professor and Agronomist. “In managing nematodes or other soil-borne pests, the important thing is rotating to a non-host crop to break the cycle. Different root types and crop residue composition help alter the way nutrients are used and cycled.”
Whether you grow cotton in the Southeast or Southwest, when you cover that furrow and pull that tractor out of that field, you’ve made the most important decisions you can make for the rest of the growing season in the battle against nematodes.
“Be it a resistant variety, selecting a nematicide, or rotating to a non-host crop, once you make that choice, you have to then sit on the sidelines to watch your peanut or cotton crop go up against Team Nematode,” reminds Kemerait. “When that furrow is covered, the game goes on. But you have called your last play, coach.”
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