The disease known as peanut smut, which attacks the pods of the oilseed and produce a black spore mass instead of the grains, concerns Brazilian producers. Although it has not been detected in commercial farms in the country yet, peanut smut has caused serious damages in Argentina, which range from increased production costs and fall in productivity to some countries' restrictions to importing the product. With the aim of keeping Brazil free from the disease, Embrapa started a study to map peanut production areas in the country and check the possible presence of the pathogen, the fungus Thecaphora frezii. The survey is being conducted jointly with farmers, with the support of entities from the sector, to determine whether the pathogen is present in commercial farms and, if that is the case, define measures to prevent dispersion. “The intention is to sample the peanut production areas of Brazil, with emphasis on São Paulo state, with the aim of detecting the causal agent or not, and based on such information, inform the action of competent authorities”, explains the Embrapa researcher Dartanhã Soares, who coordinates the initiative. Protecting Brazil from embargoes Should the pathogen be absent, one of the possible developments from the study is declaring Brazil's production areas to be disease-free, which would directly impact the Brazilian peanut export chain. Soares reports that, with the recent publication of the high production losses caused by peanut smut in Argentina, some producing and exporting countries like Australia and the United States issued a warning imposing phytosanitary barriers to peanuts from Argentina, Brazil and other countries in Latin America. “Although there is no evidence that this pathogen occurs in commercial peanut farms of Brazil, due to the lack of systematic studies that prove such premise, government authorities do not have arguments to request the exclusion of the country from such legislative restrictions”, the scientist declares. Brazilian peanut production Brazil is the second largest peanut producer and exporter of Latin America, with 466,000 tons, only behind Argentina, which annually produces around a million tons. Approximately 80% of the Argentinean production is for exports, while in Brazil this percentage is of about 30%. The state of São Paulo concentrates over 90% of the national peanut production. The phytosanitary embargoes were imposed based on a paper published in the journal Plant Disease in February of the last year. The researcher assesses that the impact of such embargoes at the moment is not so serious, since the main consumers of Brazilian peanuts are Asia and Europe, markets where the main factor analyzed is the presence of aflatoxin. “However, in light of such restrictions, it is possible that other countries do the same, following a knock-on effect. It is the case of China, a country where it was suggested that the same measures imposed by the United States and Australia are adopted. The extent to which this will actually impact Brazilian exports is still unknown. However, the imposition of legislative embargoes as a result of sanitary barriers for exports is always a major hindrance, as one can recall, for example, the case of foot and mouth disease”, Soares warns. The mapping started this year and is due to be conclued in February 2021. The priority will be the production areas that use seeds imported from Argentina. “If the farmer or technician responsible suspects the occurrence of the pathogen in their production area, they can fill out our form with the highest details possible and send us collected samples to the address mentioned in the folder”, Soares advises. The analyses of the soil, shell and grain samples will be held at no cost for farmers. Prevention At the current stage, the strategies that could be adopted to mitigate the risk of introduction are: always use certified seeds, avoid "saving" own seeds; avoid seeds imported from Argentina; in the case of seeds from Argentina, demand a CFO that certifies that the imported lot is pathogen free; treat seeds with fungicides using registered products, in the correct doses and preferrably use seeds with IST (industrial seed treatment). It is important to point out that the seed treatment will not protect the plant from infection in the fields, but rather mitigate the risk of introducing the pathogen in new areas. That is because the infection normally occurs when the gynophore (elongated pointy structure that appears after the flower is fertilized) is cast until it penetrates the soil to form the peanut pods. By then the seed treatment will have lost its effect. The project also establishes the training of multiplying agents, especially those who directly work with peanut seed production and imports. “The idea is that these multipliers can help in the identification of the pathogen, especially when seed lots imported from Argentina are used, in order to allow it to be identified while still in the initial stages of introduction and hence mitigate future damages”, he details. A close enemy The researcher reccounts that the fungus was discovered from samples of wild peanut collected in Mato Grosso do Sul, in the 1960s. “In spite of that, to date there have been no reports of the occurrence of actual damages to peanut crops in our country”, he observes. The disease has only been detected in commercial peanut farms in Argentina from the 1995/1996 crop year and, since then, it has been causing serious damages to the crop in the neighboring country. “Recent studies have shown that the pathogen is present in practically 100% of the peanut production croplands of Argentina, and losses above 50% have been observed in some cases”, Soares remarks. “As Brazil imports peanut seeds from Argentina, it is necessary to adopt prevention measures aimed at reducing the risks of introducing this pathogen in commercial peanut areas in Brazil”, the researcher warns. Peanut smut Peanut smut is a disease caused by the Thecaphora frezii fungus, a pathogen that attacks the pods, producing a black spore mass instead of the grains. According to Dartanhã Soares, the disease does not leave any symptom in the aerial plant parts, which makes detection difficult. “Normally the presence of the pathogen in the crop area is only detected when it is already widely dispersed and the damages it causes are already high. Hence the importance of preliminary studies for the detection of this pathogen in its initial stages of dispersion, in order to prevent the high production losses that have been observed in other countries”, the researcher states. The causal agent of peanut smut survives in the soil for long periods, even in the absence of the host. The disease is transmitted through seeds, the dispersion of spores through the wind, and the traffic of agricultural machinery, which facilitates its introduction in new areas of cultivation. There are no commercial fungicides registered to control the pathogen. “Efficacy trials conducted in Argentina have demonstrated that the direct application in the soil is more efficient than the foliar one. Moreover, the best results were observed with nighttime applications, due to the fact the peanut plant leaves are "closed" at such time, making the fungicide reach the soil more easily. However, the results have been quite variable and there is no safe management strategy yet”, the Embrapa researcher. Translation: Mariana Medeiros
The disease known as peanut smut, which attacks the pods of the oilseed and produce a black spore mass instead of the grains, concerns Brazilian producers. Although it has not been detected in commercial farms in the country yet, peanut smut has caused serious damages in Argentina, which range from increased production costs and fall in productivity to some countries' restrictions to importing the product.
With the aim of keeping Brazil free from the disease, Embrapa started a study to map peanut production areas in the country and check the possible presence of the pathogen, the fungus Thecaphora frezii. The survey is being conducted jointly with farmers, with the support of entities from the sector, to determine whether the pathogen is present in commercial farms and, if that is the case, define measures to prevent dispersion.
“The intention is to sample the peanut production areas of Brazil, with emphasis on São Paulo state, with the aim of detecting the causal agent or not, and based on such information, inform the action of competent authorities”, explains the Embrapa researcher Dartanhã Soares, who coordinates the initiative.
Protecting Brazil from embargoes
Should the pathogen be absent, one of the possible developments from the study is declaring Brazil's production areas to be disease-free, which would directly impact the Brazilian peanut export chain. Soares reports that, with the recent publication of the high production losses caused by peanut smut in Argentina, some producing and exporting countries like Australia and the United States issued a warning imposing phytosanitary barriers to peanuts from Argentina, Brazil and other countries in Latin America. “Although there is no evidence that this pathogen occurs in commercial peanut farms of Brazil, due to the lack of systematic studies that prove such premise, government authorities do not have arguments to request the exclusion of the country from such legislative restrictions”, the scientist declares.
Brazilian peanut production Brazil is the second largest peanut producer and exporter of Latin America, with 466,000 tons, only behind Argentina, which annually produces around a million tons. Approximately 80% of the Argentinean production is for exports, while in Brazil this percentage is of about 30%. The state of São Paulo concentrates over 90% of the national peanut production. |
The phytosanitary embargoes were imposed based on a paper published in the journal Plant Disease in February of the last year. The researcher assesses that the impact of such embargoes at the moment is not so serious, since the main consumers of Brazilian peanuts are Asia and Europe, markets where the main factor analyzed is the presence of aflatoxin. “However, in light of such restrictions, it is possible that other countries do the same, following a knock-on effect. It is the case of China, a country where it was suggested that the same measures imposed by the United States and Australia are adopted. The extent to which this will actually impact Brazilian exports is still unknown. However, the imposition of legislative embargoes as a result of sanitary barriers for exports is always a major hindrance, as one can recall, for example, the case of foot and mouth disease”, Soares warns.
The mapping started this year and is due to be conclued in February 2021. The priority will be the production areas that use seeds imported from Argentina. “If the farmer or technician responsible suspects the occurrence of the pathogen in their production area, they can fill out our form with the highest details possible and send us collected samples to the address mentioned in the folder”, Soares advises. The analyses of the soil, shell and grain samples will be held at no cost for farmers.
Prevention At the current stage, the strategies that could be adopted to mitigate the risk of introduction are: - always use certified seeds, avoid "saving" own seeds;
- avoid seeds imported from Argentina;
- in the case of seeds from Argentina, demand a CFO that certifies that the imported lot is pathogen free;
- treat seeds with fungicides using registered products, in the correct doses and preferrably use seeds with IST (industrial seed treatment). It is important to point out that the seed treatment will not protect the plant from infection in the fields, but rather mitigate the risk of introducing the pathogen in new areas. That is because the infection normally occurs when the gynophore (elongated pointy structure that appears after the flower is fertilized) is cast until it penetrates the soil to form the peanut pods. By then the seed treatment will have lost its effect.
|
The project also establishes the training of multiplying agents, especially those who directly work with peanut seed production and imports. “The idea is that these multipliers can help in the identification of the pathogen, especially when seed lots imported from Argentina are used, in order to allow it to be identified while still in the initial stages of introduction and hence mitigate future damages”, he details.
A close enemy
The researcher reccounts that the fungus was discovered from samples of wild peanut collected in Mato Grosso do Sul, in the 1960s. “In spite of that, to date there have been no reports of the occurrence of actual damages to peanut crops in our country”, he observes.
The disease has only been detected in commercial peanut farms in Argentina from the 1995/1996 crop year and, since then, it has been causing serious damages to the crop in the neighboring country. “Recent studies have shown that the pathogen is present in practically 100% of the peanut production croplands of Argentina, and losses above 50% have been observed in some cases”, Soares remarks. “As Brazil imports peanut seeds from Argentina, it is necessary to adopt prevention measures aimed at reducing the risks of introducing this pathogen in commercial peanut areas in Brazil”, the researcher warns.
Peanut smut
Peanut smut is a disease caused by the Thecaphora frezii fungus, a pathogen that attacks the pods, producing a black spore mass instead of the grains. According to Dartanhã Soares, the disease does not leave any symptom in the aerial plant parts, which makes detection difficult. “Normally the presence of the pathogen in the crop area is only detected when it is already widely dispersed and the damages it causes are already high. Hence the importance of preliminary studies for the detection of this pathogen in its initial stages of dispersion, in order to prevent the high production losses that have been observed in other countries”, the researcher states.
The causal agent of peanut smut survives in the soil for long periods, even in the absence of the host. The disease is transmitted through seeds, the dispersion of spores through the wind, and the traffic of agricultural machinery, which facilitates its introduction in new areas of cultivation.
There are no commercial fungicides registered to control the pathogen. “Efficacy trials conducted in Argentina have demonstrated that the direct application in the soil is more efficient than the foliar one. Moreover, the best results were observed with nighttime applications, due to the fact the peanut plant leaves are "closed" at such time, making the fungicide reach the soil more easily. However, the results have been quite variable and there is no safe management strategy yet”, the Embrapa researcher.
Translation: Mariana Medeiros
