More corn good, bad for peanuts

The euphoria over ethanol production got another shot in the arm with the recent release of global warming findings, which put much of the blame on burning fossil fuels. The public and political support of ethanol has driven corn prices up and up, and as of early February they were still climbing. The result is sure to be more acres of corn.

Though there is no way to know precisely what the 2007 corn crop will look like in terms of acreage and yield, it is likely to have a significant impact on other traditional row crops in the Southeast, especially peanuts.

Since it became a popular crop in the post WWII years, the classic rotation for peanuts has been two years of corn and one year of peanuts. In virtually all these years corn was the second crop to the real money crop — peanuts. Now, the roles are reversed. Corn at $4 per bushel is equivalent in value to peanuts at $600 per ton. Initial peanut contracts have been offered at $415 per ton.

Peanut production in 2007 will be plagued by increased herbicide costs, further reducing profitability. University of Georgia Weed Scientist Eric Prostko says 2005 and 2006 studies of herbicide resistance indicate weed resistance to ALS-inhibiting classes of herbicides is much more widespread in Georgia than previously thought. It is likely, he contends, this is true throughout the peanut producing states of the Southeast.

Herbicides used in corn production, especially atrazine, do a good job of cleaning up fields with weeds and grasses that are typically treated with ALS-inhibiting herbicides. From this perspective increased plantings of corn could be a big advantage for future peanut production.

A number of weeds have shown resistance to a number of herbicides, but by far glyphosate resistant Palmer amaranth pigweed is the major problem.

Though glyphosate is not used on peanuts, except in some rope wick treatments for large weeds, the best alternative to glyphosate on Roundup Ready cotton and soybeans is ALS-inhibiting herbicides. Cadre, probably the most widely used herbicide for controlling a number of weeds troublesome to peanut production, is an ALS-inhibitor. Strongarm, which is gaining in popularity, likewise is an ALS-inhibitor.

By planting corn, peanut and cotton growers can get away from using these popular herbicides, and as Prostko notes, not using herbicides to which weeds have adapted a resistance for just one year can make a big difference.

The University of Georgia scientist points out that pigweed grows rapidly. “If I make a recommendation for spraying a field for pigweed control one day and the grower waits three or four days to spray, that recommendation may not be the right one,” he says. The bottom line is that timeliness is critical in pigweed control. For any peanut field with a history of pigweed problems, it is a good bet to use Prowl or Sonolan. Rotating herbicides is essential, but usually adds production costs that many growers simply can’t afford.

Corn has long been planted as a rotation crop with peanuts to break up nematode cycles. The most serious nematode pest of peanuts is Meloidogyne arenaria Race 1, the peanut root-knot nematode. It typically affects peanuts grown on lighter, sandier soils, which are predominant throughout the peanut belt.

Pod rot, white mold, and other soil-borne diseases may increase when the peanut plant is infected with this root-knot nematode. The lesion nematode, Pratylenchus brachyurus, is less troublesome, but it can reduce yields and seriously disfigure the peanut hulls with unattractive brown lesions that lead to pod rotting.

Though some root-knot nematode reproduction could be expected on field corn, this crop is considerably less susceptible than peanuts and is generally effective in the reduction of root-knot nematode soil populations. It is a suitable crop to grow in a year following a root-knot nematode-infected peanut crop.

Losing cotton acreage may be as detrimental to nematode management as gaining corn is beneficial to production. Cotton is not a host for peanut root-knot nematodes and is a very good rotational crop with peanuts.

Increased corn production will clearly have a number of agronomic benefits to future peanut production, but there is one potentially devastating result. With corn now the money crop, some speculate it will go on the best land, and even more critical on land that is irrigated.

Peanut yields in the Southeast averaged less than 3,000 pounds per acre and in the Carolina-Virginia belt just over 3,000 pounds per acre over the past three years. Already the rule of thumb is that growers make money only on two ton per acre peanuts, they simply can’t afford yield and quality losses associated with growing on marginal land and without irrigation.

Growing dryland corn in the Southeast is risky at best. To get close to the national average of 151 bushels per acre, growers in the Southeast will have to put corn on their best land and apply water during the critical late-May to mid-June growth period. As corn growers in Alabama and Georgia learned during the early- to mid-season drought in 2006, dryland corn production under such conditions is impossible. While cotton and peanuts can recover from long stretches of heat and drought, corn cannot.

In North Carolina, North Carolina State University Corn Specialist Ron Heiniger says the use of irrigation for growing corn in North Carolina has increased steadily over the past 30 years. The major advantages of irrigation in corn production come from an increase in yield potential and more consistent yields over time.

In comparison studies of irrigated and non-irrigated corn in commercial fields over a seven year period, Heiniger found that irrigated corn fields yielded over 215 bushels per acre on average; while non-irrigated fields on the same farm over the same period averaged only 140 bushels per acre. Furthermore, the irrigated yields during the seven years ranged from 194 to 245 bushels per acre; while non-irrigated yields ranged from 13 to 204 bushels per acre.

The bottom end of the North Carolina findings, 13 bushels per acre, may be what drives growers to put as much corn as possible under irrigation. Growing dryland peanuts also can be a risky proposition, but less so than corn. And, with corn having the more favorable profitability, it is a good guess that more dryland peanuts will be planted in 2007 than in 2006.

Peanut production reached nearly 2.5 million tons in 2005, creating a carry-out of over 53 percent more than demand. Dell Cotton, director of the Virginia Peanut Growers Association, says a 30-35 percent carry-out is a good balance. A 29 percent drop in acreage in 2006 brought the carry-out to a more manageable 36.5 percent.

Cotton expects another drop in peanut acreage of 10 percent or more for 2007. Even with above average yields, that could create a demand for peanuts that would drive prices up and be an economic benefit for the next few years.

Overall, increased corn acreage in the Southeast should have a positive benefit for peanut producers. In fact, most peanut farmers are also cotton or corn farmers, making the transition a natural one for either a switch to corn or an increase in current corn acreage.

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