What is in this article?:
• 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.
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.