Farm Progress

• In sifting through more than a decade’s worth of data from Peanut Profitability winners, Research Director Marshall Lamb and his staff at the National Peanut Research Lab found that rotation was a nearly universal commonality among the honorees.• Rotation, says Lamb, is one those tried and true production methods that growers tend to take for granted, at least until they stop practicing it.

Paul L. Hollis

June 19, 2012

7 Min Read
<p> EFFECTIVE CROP ROTATION is a tried-and-true method for reducing disease and increasing yield in peanuts.</p>

Organizers of the Farm Press Peanut Profitability Award have reviewed production data from previous winners to arrive at a “Top 10 Keys to Peanut Profitability.” This list of successful production practices is being presented in descending order in Southeast Farm Press and on this website, with sponsorship provided by DuPont Crop Protection. The Peanut Profitability Awards, based on production efficiency in whole-farm situations, is entering its 13th year and is administered by Marshall Lamb, research director for the National Peanut Research Laboratory, and his staff.

If you’ve been farming for any length of time, it’s a familiar refrain by now — the keys to success in any cropping system are rotation, rotation, rotation.

It’s certainly no different in peanuts, and it’s the reason rotation comes in at No. 2 on the Top 10 Keys to Peanut Profitability.

The primary benefit of rotation, of course, if that it reduces the severity of disease, and disease control continues to be the leading cost input for peanut producers, especially in the Southeast.

In sifting through more than a decade’s worth of data from Peanut Profitability winners, Research Director Marshall Lamb and his staff at the National Peanut Research Lab found that rotation was a nearly universal commonality among the honorees.

Rotation, says Lamb, is one those tried and true production methods that growers tend to take for granted, at least until they stop practicing it.

Simply put, increasing the number of seasons between consecutive peanut crops in the same field has been shown to reduce disease levels and increase yields.

Specialists with the University of Georgia Extension Peanut Team advise that the fungal pathogens that cause leaf spot, rhizoctonia limb rot and white mold all survive between peanut crops on peanut crop debris, as survival structures in the soil, and on volunteer peanuts.

The time between consecutive peanut crops allows for the deterioration of peanut crop debris, thus depriving the fungal pathogens of a source of nutrition.

Also, fungal survival structures and spores that are present in the soil have a certain period of viability in which to germinate and infect another peanut plant before they are no longer viable.

Leaf spot diseases

 The specialists say that fields with longer crop rotations will have less pressure from leaf spot diseases, rhizoctonia limb rot, white mold, and perhaps CBR, than fields with shorter rotations, or no rotation at all.

In Georgia, the Cooperative Extension Service recommends at least two years between peanut crops to help manage diseases. Longer rotations have proven beneficial for Peanut Profitability winners.

The choice of rotation crops, along with the length of the rotation, will have an impact on the potential for disease in a field. Rotation of peanuts with any other crop will reduce the potential for early leaf spot, late leaf spot and peanut rust. The pathogens that cause these diseases do not affect other crops.

Rotation of peanuts with cotton or a grass crop such as corn, sorghum or bahiagrass, will reduce the potential for white mold because the white mold pathogen does not infect these crops, or at least not very well.

Rotating peanuts with a grass crop will reduce the risk of rhizoctonia limb rot.

However, because cotton is also infected by rhizoctonia solani, rotation with this crop will not help to reduce rhizoctonia limb rot.

Other crops, such as tobacco and many vegetables are susceptible to diseases caused by rhizoctonia solani and will not help to reduce the severity of limb rot in a peanut field.

While favorable prices have made soybeans more popular in the Southeast, Extension specialists say that growers must remember soybeans and peanuts are affected by many of the same diseases.

Planting soybeans in rotation with peanuts will not reduce the risk for CBR or peanut root-knot nematodes and will have only limited impact of risk to white mold and rhizoctonia limb rot.

While the primary recommendation is that a grower plant peanuts in a field only once every three years, once every four years is even better, according to research and producer experience.

In recent years — due to changes in government farm programs and improved prices — peanut acreage has expanded into “non-traditional” production areas in the Southeast.

As a result, growers in these areas want to know if they can grow peanuts on their land in back-to-back seasons since they’ve never before grown them.

However, even these producers should be discouraged from back-to-back peanuts, say University of Georgia experts.

With new peanut ground, it’s likely that populations of pathogens attacking the crop will initially be low. Therefore, it doesn’t make much sense to lose this competitive edge in pursuit of the short-term goal of growing two or three crops of peanuts in succession.

Also, many new peanut growers are producing peanuts on land that has been cropped to cotton in recent years. Although cotton is not affected by peanut root-knot nematodes, early or late leaf spot or CBR, and is only slightly affected by white mold, it is susceptible to diseases caused by rhizoctonia solani.

It is likely that despite previous cropping in a field, there will be significant populations of this disease and perhaps smaller populations of white mold in the field when peanuts are first planted. Without effective crop rotation, these populations may increase quickly.

In 2005, an outbreak of CBR was observed in a field in southeast Georgia that had been planted for two consecutive years to peanuts, but had not been planted to peanuts at any other time.

Soybeans introduced the problem

Specialists say that earlier crops of soybeans had introduced this disease to the field and that back-to-back years of peanuts had intensified the problem.

One of the greatest benefits of crop rotation is that it increases the effectiveness of all disease management programs.

Effective crop rotation helps to take the pressure off of a fungicide program to minimize the impact of disease. Any fungicide program will be more effective where good crop rotation is practiced.

In some situations, fields that are well rotated will require fewer, or at least less expensive, fungicide applications by the grower.

Recommendations from the University of Georgia for crop rotation and peanut production include the following:

1.) Avoid planting peanuts in the same field more than once out of every three years. Longer rotations, for example, once every four years, are even better.

2.) The best crops to rotate with peanuts are grass crops such as corn, sorghum and bahiagrass. These crops will help to reduce the severity of diseases caused by rhizoctonia solani, as well as CBR, white mold and leaf spot diseases.

Although corn and sorghum are alternate hosts for the peanut root-knot nematode, they are less affected than peanuts are. Therefore, planting corn and sorghum should help to reduce populations of peanut root-knot nematode, though perhaps not as fast as when a non-host such as cotton is planted.

Bahiagrass is susceptible to the lesion nematode, which can reduce the pod brightness important for the green peanut market.

3.) Cotton is a very good rotation crop with peanuts and should help to reduce the severity of white mold, leaf spot diseases and CBR on future crops.

Cotton is not a host for the peanut root-knot nematode, so this will be a beneficial effect as well. Cotton is a host for rhizoctonia solani, so diseases caused by this pathogen will remain a concern in peanut-cotton rotations, especially in conservation tillage where crop debris remains on the surface.

4.) Soybeans, other leguminous crops, and many vegetable crops are not preferred for rotation with peanuts. Although such rotations are likely to reduce the severity of leaf spot diseases, they may not reduce the severity of white mold, rhizoctonia limb rot, the peanut root-knot nematode, or, in the case of soybeans, CBR.

(An introduction to this series of keys to peanut profits can be found here. Keys No. 10 and No. 9 can be found here. No. 8 and No. 7 are here. Cost management, efficient water use two more keys to peanut profits came in at No. 6 and No. 5. Disease control ranked No. 4 and that information can be found here. The No. 3 key was listed as proactive farm management. That information is available here).

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About the Author(s)

Paul L. Hollis

Auburn University College of Agriculture

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