Producing peanuts that meet certified organic criteria set by the USDA with restrictions set by the National Organic Program (NOP) can be challenging compared with conventional peanut production. However, demand for organically produced peanut is strong, and markets are available. The two major agronomic challenges with organic production are obtaining adequate plant stands and effectively controlling weeds. While disease, insect, and nematode control can be difficult to achieve, in most instances the impacts of insects and nematodes, and in some cases in-season diseases, may reduce yields but are not catastrophic. In contrast, the susceptibility to fungal disease in peanut seedlings without fungicide seed treatment and the challenge of controlling grassy weeds in an organic peanut system can result in complete crop failure. Growers interested in producing peanuts using organic principles should plant when soil conditions favor rapid emergence of seedlings. Fields with low infestations of weeds should be selected for production.

Challenges also exist from a post-harvest perspective. The certification process does not end in the field but carries through all processing steps. This can be a major constraint to organic adoption because current shellers in the Virginia-Carolina region are too large to invest in transitioning their plants to a relatively small volume of peanuts for organic certification. For example, Hampton Farms markets several products that are certified organic, but all production is based in New Mexico because of shelling and processing logistics and certification requirements at the post-harvest level.

From 2016 to 2019, the North Carolina Agricultural Foundation provided funding to develop elements of an organic peanut value chain in North Carolina. This project included efforts to increase efficiency of production, determine consumer demand and potential farmer involvement, and establish a pilot project with selected certified organic growers in the state. The goal of the project was to assist growers in producing certified organic peanut for the in-shell trade.

Our goal in this chapter is to provide information on requirements for certified organic production, basic agronomic practices required for certified organic production of peanuts, challenges with pest management in certified organic production, and estimated costs of certified organic production.

Variety Selection

Variety selection most likely will vary little in organic and conventional production systems. One of the major focal points of the breeding program at North Carolina State University is the development and release of varieties that express field tolerance or resistance to pathogens and tomato spotted wilt. Detailed information on the strengths and weaknesses of varieties to diseases are provided in Chapter 6, “Peanut Disease Management,” of the Extension publication Peanut Information (AG-331). Briefly, the Virginia market-type varieties Bailey and Sullivan have relatively good resistance to leaf spot diseases, tomato spotted wilt, Cylindrocladium black rot, and Sclerotinia Blight, especially relative to older varieties. However, these varieties are not immune, and a well-implemented production package that includes crop rotation and cultural controls is needed for success. The resistance characteristics of these and other varieties are important to consider in both conventional and organic systems. It is important to note that growers might plant Spanish, Valencia, or runner market types, and possibly Virginia market-type varieties not commonly grown in North Carolina, in their organic production systems. If that is the case, make a strong effort to know the susceptibility of these varieties to pathogens commonly found in North Carolina. Detailed information on the strengths and weaknesses of varieties to diseases are provided in Chapter 6, “Peanut Disease Management,” in the current edition of Peanut Information.

Crop rotation serves as the foundation of successful peanut production in North Carolina for conventional production systems (see Chapter 3, “Peanut Production Practices,” and Chapter 6, “Disease Management” in the current edition of Peanut Information for more details. Principles of good rotation for conventional peanut production also hold true for organic production. Rotations to non-hosts reduce populations of disease-causing fungi and nematodes and can minimize the negative impact of these pathogens on peanut health and productivity. This practice is especially critical in organic production due to the absence or limited efficacy of fungicides, nematicides, and seed treatments that are OMRI-approved for disease control. Long rotations are necessary to suppress diseases, especially those caused by soilborne plant pathogens.

Corn, cotton, small grains, and other grasses typically are the best rotation crops for reducing pathogen infestations. However, some grain and grass species are not good rotations for nematode suppression. Soils should be assayed before planting for potential nematode problems, and infested areas should be avoided. Sweetpotato is also a good rotation crop for peanut while soybean and tobacco are generally considered less effective rotation crops. Knowledge of specific pathogens and nematodes is important in developing effective cropping sequences and may allow plantings of less effective crops in some cases. However, it is generally accepted that over time, less-effective rotations and crop sequences will create challenges in protecting yield.

Crop rotation does not have a major impact on most insects that affect peanut. However, crop diversity can impact insect pests on farms and subsequent movement from crop to crop. See Chapter 5, “Peanut Insect and Mite Management,” in the current edition of Peanut Information for discussions of spider mites and other arthropods that are mobile.

Weed control in previous crops can have a major impact on weeds in both organic and conventional production systems (see Chapter 4, “Peanut Weed Management” in the current edition of Peanut Information). However, there are no salvage treatments in organic production systems for weeds, and farmers should avoid fields with moderate-to-heavy weed pressure. It is necessary to ensure weeds that were controlled relatively well in previous crops do not grow and reproduce after these crops are harvested. Fields should be tilled as needed after harvest to keep weeds from reproducing late in the summer or early in the fall. Managing the soil seed bank is a critical component of organic crop production.

Reduced-tillage systems are used by approximately 20% of peanut growers in North Carolina. While conservation tillage has been adopted more widely in other row crops, the requirements of digging pods and vine inversion are often more challenging in reduced-tillage systems. In these systems, peanuts are often grown in seedbeds with residue from the previous crop or in a desiccated cover crop. Pod loss is often greater when peanuts are dug in fields that are flat and not tilled without new rows prepared in spring. This is also the case for organic production systems.

A second major challenge in reduced tillage in organic systems is controlling weeds prior to planting but before peanuts emerge. There is simply no way to control winter vegetation and emerged summer weeds without synthetic herbicides. Although reduced tillage often results in fewer weeds emerging with the crop, and high residue cover crops such as cereal rye can suppress weeds to a great degree, these approaches are generally not completely effective and would interfere with the multiple cultivations with a tine weeder that are needed during the first month of the season (see the next section on weed management). Soils in reduced tillage, especially if seedbeds are flat, often warm more slowly in spring. These soils often hold more soil water, resulting in cooler soils that impact stand establishment, especially when pathogens that affect seed and seedlings are present. Higher seeding rates are required to obtain adequate stands. While cover crops can suppress weeds, timing of planting peanuts in late May often decreases biomass available for weed suppression. Leaf spot, stem rot, and tomato spotted wilt can be suppressed in reduced tillage, but challenges with stand establishment and early season weed control far outweigh potential benefits.

Soil fertility in conventional production systems is often addressed in the crop preceding peanut, although growers are encouraged to sample soils frequently for nutrients to obtain timely recommendations and to adjust soil pH to optimum levels (see Chapter 3, “Peanut Production Practices” in the current edition of Peanut Information. However, more and more growers in conventional production systems are applying remedial amounts of fertilizer to make sure peanuts do not lack essential nutrients. Addressing fertility in organic production systems can be more challenging than in traditional production systems. OMRI-approved organic fertilizers have slower rates of mineralization, meaning they are less readily available to plants when applied. For this reason, farmers should consider applying adequate amounts of fertilizer in the previous crop to meet the demands of the following peanut crop.

OMRI-approved inoculants that contain Bradyrhizobia bacteria essential for biological nitrogen fixation (BNF) are available for peanuts. It is very important to apply adequate amounts of inoculant to seed or in the seed furrow at planting to ensure adequate infection of roots for BNF (see Chapter 3 on peanut production in Peanut Information for more details). This is especially the case if organic peanuts are planted in fields without a history of peanut production. In these fields, there is no backup in the form of native Bradyrhizobia species. Synthetic nitrogen fertilizer can be applied quickly if inoculants fail in conventional production systems, and much of the yield potential can be realized when ammonium sulfate is applied after an inoculant failure; however, this is not an option in organic production systems.

Supplemental calcium in the form of calcium sulfate or gypsum should be applied to Virginia market-types to ensure adequate kernel development. OMRI-approved gypsum sources are available and should be applied at pegging. OMRI-approved formulations of manganese and boron are also available. These micronutrients are often needed to optimize peanut yield. Growers are also cautioned that use of poultry or swine litter, even from many years ago, can result in levels of zinc that limit yield. Fields should be avoided if zinc levels exceed NCDA&CS indices of 250.

Digging peanut and inverting vines will be similar in organic production systems compared with traditional production systems in most instances. However, more weeds, especially annual grasses, are likely to be present in organic systems than in conventional systems, and this can increase pod loss during digging and vine inversion. Weeds above the canopy can be mowed within two weeks of digging, but it is important to track rows precisely so that peanut rows can be clearly seen for effective digging. Rapid and haphazard mowing can make tracking rows extremely difficult. To prevent pod loss during the digging process, the implement must be positioned within just a few inches of optimum tracking.

Farmers might experience greater pod shed due to less-effective fungicides for leaf spot in organic systems compared with conventional systems. In some fields, peanut will need to be dug prior to optimum pod maturity to prevent excessive yield loss. The balance between pod loss from defoliation caused by leaf spot disease and not allowing enough time for peanut to reach full maturity is discussed in more detail in Chapter 3, “Peanut Production Practices,” and Chapter 6, “Peanut Disease Management” in Peanut Information.

DO NOT attempt to grow peanuts in fields with moderate-to-high levels of weeds, especially if annual or perennial grasses, common ragweed, nutsedge, or Palmer amaranth are present. Grasses are particularly hard to manage because of their fibrous root system, which makes them difficult to remove by hand or hoeing and causes greater pod shed during digging and vine inversion.

While heavy-residue cover crops–cereal rye in particular can suppress weeds, tillage systems that allow frequent cultivation within the first month of the season have proven to be the most effective approach to organic peanut production. In these systems, fields are weed-free at the time of planting peanut at a depth of 3 inches. Cultivation with a tine weeder should begin no later than three days after planting even though peanuts have not emerged. This operation will kill young seedlings below the soil surface, especially grasses. At least five more cultivations at weekly intervals are recommended using a spring-loaded tine weeder. The root system of peanuts planted at a depth of 3 inches will be anchored relatively well, and while some foliar damage will occur and some plants will be occasionally removed from soil by tines, intensive cultivation in this manner is the only way to minimize weed interference and prevent weed-control failure. Cultivators with sweeps can also be used as peanut plants grow larger. Soil from these cultivators can be deposited around the base of each plant to bury and suppress weeds in the peanut drill line. This approach to weed control is different from recommendations in conventional production systems with respect to cultivation. In conventional systems, in-season cultivation is discouraged because of movement of soil that may contain pathogens onto peanut plants. Cultivation also brings soil to the surface that has not been treated with herbicide. Nonetheless, an aggressive approach to in-season cultivation with a tine weeder that covers the entire row is absolutely critical for success in organic peanut production. The value of weed control from these operations outweighs the negative impact of increased infection by pathogens.

Some weeds will need to be removed by hand in organic production systems. This practice is also true of conventional production systems when herbicides are not completely effective, especially when herbicide-resistant biotypes are present. In organic production, however, timeliness of weed removal by hand is needed not only to avoid interference with yield by weeds but also to minimize damage to peanut plants when physically removing weeds by hand or with implements.

There are currently no OMRI-approved chemicals that control weeds effectively in peanut.

Thrips, southern corn rootworm, caterpillars, leaf hoppers, and spider mites can be suppressed in conventional tillage systems with insecticides. There are a few OMRI-approved insecticide options to control foliar-feeding insects. Products that contain spinosads, neem extract (azadirachtin), Bacillus thuringiensis, insecticidal soaps, and pyrethrins are available as organic products for insect management. Growers should adjust cultural practices to minimize the likelihood of an infestation and the impact of insects (see Chapter 5, “Peanut Insect and Mite Management,” in the current edition of Peanut Information). However, sometimes a practice that minimizes the impact of one insect on peanut can increase the potential for another insect to damage the crop. For example, planting as late as possible in May minimizes injury potential from thrips in some years and can lower incidence of tomato spotted wilt compared with earlier plantings. Planting later in May increases potential from southern corn rootworm. In light, sandy soils, however, which pose a low risk from rootworms, this later planting may be a viable option to suppress early-season thrips damage.

Unlike the catastrophic nature of a failure in stand establishment and early season weed control in organic peanut, yield loss from insects is often more incremental and generally will not result in complete yield loss. However, the presence of numerous arthropods that affect yield individually can ultimately result in yield losses that approach 15% to 20%. Maintaining good plant health will always make the plants more tolerant of insect feeding and less likely to suffer yield loss.

Unfortunately, the search for host plant resistance to insects in peanuts has not been productive, and varieties currently grown in North Carolina do not offer adequate resistance to insects to be considered a control strategy. While thrips vector tomato spotted wilt virus and variety selection can have a major impact on expression of tomato spotted wilt in peanuts, resistance is not associated with impacts on thrips but is related to physiological effects of the virus within the peanut plant. Likewise, variety selection can impact damage from southern corn rootworm but is not related directly to resistance to feeding by the insect. Less pod scarring from southern corn rootworm occurs with some varieties because the resistant variety requires less time to reach optimum maturity and possesses hulls that are more fully developed when larvae begin feeding on pods. See both the Southern Corn Rootworm index and the Tomato Spotted Wilt Virus index in Chapter 5, “Insect and Mite Management,” in the current Peanut Information for more information on management of these pests.

Several OMRI-approved insecticides are available that are effective in controlling leaf hoppers, thrips, and caterpillars. Although insecticidal soaps can suppress spider mites, they require excellent coverage. And under the hot, dry conditions that create spider mite outbreaks, these products may cause severe phytotoxicity. However, while any and all of these insect pests can injure peanuts, they often do not occur at populations that result in serious yield reductions, and an overall organic production program can help preserve beneficial organisms that help limit pest populations.

Seedling diseases may be the greatest threat to organic peanut production because they can result in almost complete stand failure depending on weather and soil conditions at planting. This threat is the case even in conventional production systems whenseed is not treated with fungicides. Several OMRI-approved products are available to suppress seedling pathogens, but these products are often less effective than the synthetic seed treatments in conventional production systems that are described in Chapter 6, “Peanut Disease Management,” in the current edition of Peanut Information.

As stated in the introduction to this chapter, failure to establish an adequate stand and ineffective weed control are considered the most yield-limiting challenges in organic peanut production. For this reason, farmers are encouraged to plant peanut as late as possible within the effective planting window (late May) and increase the seeding rate by 50% to 75% compared with seeding rates used in conventional production systems where synthetic fungicides are applied to seed before planting. Soil is warmer in late May than in early and mid-May, and this warmth most often results in more rapid emergence of peanut. The longer peanut seed and seedlings remain in soil prior to emergence, the more likely it is that soilborne pathogens will cause seeds to rot. Pathogens also cause seedlings to die before and after emergence.

With the exception of systemic insecticides that suppress thrips, cultural practices that are effective in reducing tomato spotted wilt are the same for conventional and organic production. Planting in May and at a seeding rate that ensures four to five plants per foot can reduce incidence of tomato spotted wilt virus.

Most Virginia market type peanut varieties grown in North Carolina express resistance to one or more diseases typically found in peanut fields. Varieties available for both conventional and organic producers are much more effective at withstanding disease than varieties grown a decade ago or longer. However, current varieties are not completely immune to disease. In both organic and conventional production systems, there is concern that these varieties are less effective in withstanding disease now than when they were first adopted by growers.

Several OMRI-approved fungicides (usually copper and sulfur compounds) are available that can be used in organic peanut production with restrictions on conditions for use. These fungicides are not as effective as synthetic fungicides used to control leaf spot and require more frequent applications at shorter intervals. These products are most effective at protecting against infection when applied as a preventative in disease risk environments. Good coverage is essential. There are no OMRI-approved fungicides for control of diseases caused by soilborne pathogens such as stem rot and Sclerotinia blight. Biological control products are only marginally effective against soilborne pathogens and nematodes. As mentioned above, rotation is critical for maximizing the potential benefits of other disease control tactics. Yield most likely will be lower in organic production systems than in conventional production systems due to less effective management options for economically important diseases.

Research on the potential for organic peanut production in North Carolina, supported through the North Carolina Agricultural Foundation, was completed from 2016 to 2019. Trials at research stations were conducted to investigate differences in yield between organic peanut production and conventional peanut production. To mirror an organic peanut production system, researchers used higher seeding rates, untreated peanut seed, and did not use conventional insecticides or fungicides throughout the trial. Researchers did use an organically approved copper fungicide to control leaf spot within the organic plots. For the conventional comparison, peanut was planted at a typical seeding rate with fungicide-treated seed, and conventional insecticide and fungicide were used in the trial. Yield in the simulated organic system was approximately 20% lower than yield in the conventional system. Yield most likely would be even lower due to weed interference and possible fertility issues in the organic system. These studies were helpful in demonstrating yield potential in organic peanut production compared with conventional production with respect to disease and insect control.

The project also included participation with two experienced organic growers who were interested in incorporating peanut into their established organic production systems. One of these growers had a substantial amount of organically produced tobacco and sweetpotato. While the research station field trials for organically managed peanuts were successful, the participating growers were unable to produce an organic peanut crop for 2017 or 2018. Rainfall disrupted cultivation after planting in 2017 and a heavy rain severely delayed planting and cultivation in 2018. The timing of rainfall in both years resulted in an inability to manage weeds with tillage. The limitation in tools that allow weeds to be controlled quickly without tillage pose a major challenge to organic peanut production, and as growers consider this approach and marketing opportunities, they will need to be aware that a higher frequency of failure will occur compared with conventional production systems, at least with weed management tools currently available in peanut.

There is an old adage among farmers that, “a dry year will scare you to death, but a wet year will kill you.” That phrase was coined during a time when few herbicides were available and most weed control in peanut was achieved through cultivation and hoeing. Researchers involved with organic peanuts in Georgia indicated that they have had more success in dry years than during years with average or above-average rainfall. In fact, most organic peanuts are grown in New Mexico under arid conditions with irrigation. In that system, water can be managed in a way that does not interfere with weed control operations. Likewise, dry conditions and low humidity strongly suppress the activity of many plant pathogens. In North Carolina, the challenge of timely weed control with cultivation and hoeing will exist for organically produced peanuts because rain can be unpredictable and abundant in May and June.

As part of this project, surveys were conducted to capture the attitudes and perspectives of organic growers lacking experience with peanuts, conventional peanut growers who might be interested in expanding their operation to include organic peanut, and small specialty shops that cater to consumers who prefer organically certified food. Results from the survey of 218 conventional peanut growers in North Carolina, South Carolina, and Virginia indicated that 20% of these growers were interested in growing peanuts organically. Growers were asked what price point they would need to receive to consider organic production, their expectations of organic peanut yield, and what their top concerns were for organic production. About half of the respondents indicated they would need a price point triple that of conventional peanut, and 27% indicated they’d need to receive a price point double that of conventional peanut; while 9% and 16% indicated they would need to receive a price point of 1.5 and 2.5 times that of conventional peanut production, respectively.

Yield expectations among conventional growers for organically produced peanuts varied. Six percent of conventional growers indicated they would expect no difference in yield; nearly one fourth indicated they would expect a 25% decrease in yield; over half indicated a 50% decrease in yield; and 12% expected a 75% decrease in yield from transitioning to organic management. The top concerns of conventional growers in transitioning to an organic system (in order of importance) were disease, weed pressure, insect pressure, nematodes, stand establishment, and fertility. Another concern for growers was the three-year transition period to certified organic production, access to organic markets, and maintaining a split operation of organic-conventional production. Overall, the survey indicated a considerable interest in organic production by conventional peanut growers, but substantial concerns over production challenges, yield potential, and market access as well as the need for a significantly higher price point to consider transitioning to organic production.

Rick L. Brandenburg, Extension Specialist, Department of Plant Pathology and Entomology

Chris Reberg-Horton, Extension Specialist, Department of Crop and Soil Sciences

S. Gary Bullen, Extension Economist, Department of Agricultural and Resource Economics

Amanda Kaufman, Graduate Student, Department of Food, Bioprocessing, and Nutrition Sciences

Lisa Dean, Research Food Technologist, Market Quality and Handling Research Unit, United States Department of Agriculture, Southeast Area

Bob Sutter, Chief Executive Officer, North Carolina Peanut Growers Association Inc.