In a 1977 Question-and-Answer Session with Department of Agriculture employees, President Carter recalled the tremendous growth in peanut yields on his Georgia farm which resulted when they stopped plowing. He credited research that showed that more plowing meant less yield. It turns out that he was right: the plowing spread disease that lowered peanut yield. Herbicides made the reduction in plowing possible and improvements in herbicides have continued to benefit peanut farmers.
“Improvements in weed management are a contributing factor to advancements in peanut yield. …Cultivation was traditionally an integral component in peanut weed management. New herbicide developments improved overall weed control and cultivation is no longer needed. This directly addresses the susceptibility of peanut to infection by soil-inhabiting fungi. There is a direct correlation between incidence of stem rot and displaced soil thrown on peanut plants from cultivation. Not needing to cultivate lessens disease epidemics and protects peanut yield. In 2013, 21 herbicide active ingredients were registered in the U.S. for weed control in peanut. In contrast, there were 12 herbicide active ingredients registered for use on peanut in 1980. Recently developed herbicides are more consistent, versatile, and have a broader-spectrum than earlier herbicides. …There were no selective postemergence herbicides registered in 1980 that controlled emerged grasses. In 2013, there were three postemergence herbicides registered for use on peanut to control annual and perennial grasses…. Registrations of these herbicides were major weed control milestones in peanut production and have largely eliminated yield losses from grasses that escaped earlier control efforts.”
Author: Johnson, W. C.
Affiliation: USDA-ARS, Tifton GA
Title: Yield Advances in Peanut – Weed Control Effects
Source: 2013 Proceedings of the American Peanut Research and Education Society, Inc. http://apresinc.com/wp-content/uploads/2014/02/Volume-45-Proceedings_2013.pdf
The unrelenting rains of 2013 in southeastern peanut fields created perfect conditions for the rapid development of white mold and rhizoctonia- diseases that can cause plant death. However, disease outbreaks did not occur because peanut growers were vigilant in applying fungicides.
“So far, 2013 has been a perfect weather year for peanut diseases in the Deep South: wet with swampy plus short spurts of hot with swampy.
But that disease pressure just hasn’t hit yet.
“Despite my repeated and dire predictions for severe disease outbreaks this year in our peanut fields, the reports from county agents have been fairly quiet.
…I know of very few situations where disease has overwhelmed a (peanut ) crop,” said Bob Kemerait, plant pathologist with the University of Georgia Cooperative Extension.
Why have peanut diseases not been so bad?
“Fungicides” is the short answer, he said, good fungicide products matched with grower know-how on best ways to use them.”
Author: Haire, B.
Affiliation: Reporter, Southeast Farm Press
Title: Grower know-how, good fungicides keeping peanut diseases at bay.
Source: Southeast Farm Press. August 9th, 2013. Available at: http://southeastfarmpress.com/peanuts/grower-know-how-good-fungicides-keeping-peanut-diseases-bay
Fungicide Experiment: Ghana (top=untreated bottom=treated)
Peanuts (or groundnuts) are widely used as a food by Africans as they are a major source of protein. The productivity of peanut in Africa is very low which is particularly attributed to foliar diseases. Disease severities are so high in Africa that at harvest 80% of the leaves on peanut plants are defoliated. Research has shown that application of fungicides can successfully control diseases of peanuts in Africa and lead to substantial increases in yield.
“Lower productivity of peanut in West Africa is attributed to biotic factors (mainly foliar diseases)…
Farmers usually attribute leaf defoliation to maturing of the crop, and yield loss from foliar diseases is not recognized. Fungicide use is not a common practice in developing countries of this region partly because of lack of resources and lack of awareness of the extent of economic and yield benefits from application of fungicide.
Data on yield benefits under on-farm studies should be quantified to bring awareness to agricultural communities, and to improve access to capital resources to demonstrate that fungicide application can be economically viable with greater returns.
The objectives of our research were to quantify yield losses due to disease and to demonstrate the influence of fungicides and SSP fertilizer application on severity of leaf spot, dry matter production and pod yield of peanut crops grown in on-station and on-farm conditions in Northern Ghana, which is representative of the important peanut producing regions of West Africa.
Applications of fungicide were effective in controlling leaf spot and improved peanut pod yield on average by 48% in the three tested village sites under on-farm conditions and by about 40% under on-station conditions at two sites.
…farmers have an interest in adopting new technologies if they are certain of economic benefits. In view of the tremendous yield advantage, fungicide recommendations are being made to peanut farmers in this region.”
Authors: Naab, J. B., et al.
Affiliation: Savanna Agricultural Research Institute
Title: Response of peanut to fungicide and phosphorus in on-station and on-farm tests in Ghana
Source: Peanut Science. 2009. 36:157-164.
Fumigated and Non-Fumigated
The disease known as cylindrocladium black rot (CBR) grows best in cool soils and is a major problem in the Virginia and North Carolina peanut regions. Entire pods may turn black and rot. The fungus may survive several years in the soil. Disease incidences in excess of 80% have occurred. The soil fumigant, metam sodium applied 8-10 inches below rows at least two weeks prior to planting has been the standard recommendation for control of CBR since 1985. Recently, the USEPA conducted a study of the value of metam sodium for peanuts and concluded that…
“Thus, the main benefit of metam sodium is that it permits cultivation of peanuts that would otherwise not be economically viable. …a large proportion of peanut acreage in the North Carolina-Virginia region depends on metam sodium simply to make production economically viable.”
Authors: A. Chiri, and T. J. Wyatt
Affiliations: EPA, Office of Pesticide Programs, Biological and Economic Analysis Division.
Title: Assessment of the Benefits of Soil Fumigation with Metam Sodium in Peanut Production.
Publication: U.S. EPA. (2007). Assessment of the benefits of soil fumigation with metam sodium in peanut production (DP#337490). Available at http://www.regulations.gov/#!home
In the U.S., fungicides are used in the field to control ten major diseases of peanuts. For decades, peanut harvesting started when the peanuts in a field were stripped of their leaves by one of these diseases. Peanut yields increased dramatically between 1969 and 1987 following the introduction of effective synthetic chemical fungicides. Fungicides continue to be needed to maintain high peanut yields.
“It’s one of the harsh realities of growing peanuts in the Southeast – you will have disease problems. ‘The same type of weather and climate that helps you grow peanuts so successfully in the Southeastern United States also makes it difficult to control diseases,’ says Bob Kemerait, University of Georgia Extension plant pathologist. Fungicide programs, he adds, constitute the single most expensive input a grower will have in peanut production. ‘It’s not seed, insecticides or herbicides. You spend more in fungicides than perhaps anything else – that’s the bad news. The good news is the tremendous value you receive from controlling diseases. We could not make the desired yields and grades without these programs,’ says Kemerait.”
Author: Paul L. Hollis
Title: Peanut fungicides valuable tools.
Publication: Southeast Farm Press. 2008. Vol. 35(12).
Our 39th President, Jimmy Carter, grew up on a peanut and cotton farm long before herbicides were available to manage weeds. In his autobiography, President Carter recounts the nightmare of trying to control weeds with tractors and hand labor.
“Our part of Georgia receives about fifty inches of rain during an average year, mostly during the spring and early summer… However, depending entirely on draft animals and hand labor, small variations in the rain pattern could be devastating. … The dry ground permitted the mule-drawn cultivating plows and hoes to restrain the ever-encroaching weeds and grass. However, when no plowing was possible because of several successive days of rain, the noxious plants were uncontrollable. Something like the terrible creeping and oozing things in horror movies, Bermuda grass, coffeeweed, cocklebur, Johnsongrass, beggar-lice, and nut grass would emerge from what had been a cleanly cultivated field, and in a few days our entire crop of young peanuts and cotton could be submerged in a sea of weeds. Often, despite the most heroic efforts by the best farmers, parts of the crop would have to be abandoned. Although partially salvaged, the remaining young plants were heavily damaged by the aggressive plowing and hoeing. During these rainy times, Daddy would pace at night, scan the western skies for a break in the clouds, and scour the community, often far from our own farm, to recruit any person willing to hoe or pull up weeds for day wages.”
Author: Jimmy Carter
Publication: An Hour Before Daylight: Memories of a Rural Boyhood. 2001. Simon & Schuster, New York.