Embrapa and Fundação Bahia guide producers on the occurrence of root rot

Researchers from the Brazilian Agricultural Research Corporation confirmed the occurrence of Phytophthora root rot in soybean plants collected in the western region of Bahia. The diagnosis was obtained from plants collected in the field in December 2019. The occurrence of the disease was reported to the Bahia State Agricultural Defense Association (ADAB). The alert to producers in the region is being made in partnership with Fundação Bahia. 

The first symptoms of the disease in the region began in the 2017/2018 harvest, when seedlings and adult plants died with root rot and browning of the stem. Attempts to confirm the cause of the problem were carried out at the time, but, however, the typical structures of the pathogen were not observed in the samples collected. “It is a pathogen that is difficult to detect, a thorough examination of the plant roots must be carried out,” explains researcher Claudine Seixas, from Embrapa Soja, who worked together with researchers from Embrapa Algodão and Embrapa Cerrados, based in western Bahia. 

In mid-December 2019, technicians from Fundação Bahia and researchers from Embrapa collected new samples of roots from soybean plants, from different cultivars with the same symptoms previously observed in the region and, in this case, the presence of characteristic structures was confirmed. of the pathogen, thus confirming the cause of the observed symptoms. 

Symptoms of Phytophthora root rot can be observed from pre-emergence through grain filling. Seed rot may occur resulting in initial stand failure and the need for area reseeding. Young plants, which are more susceptible, die quickly. Adult plants die slowly, the roots rot, turning dark brown, which progresses to the stem and can reach the lateral stems, the leaves turn yellow and dry. Symptoms occur in bushes or isolated plants, in areas of compacted soil and/or accumulation of moisture.

“The pathogen is not spread by wind and control is achieved through the use of resistant soybean cultivars, as well as seed treatment with specific products for this type of pathogen and good soil management that prevents the accumulation of water on the surface. ”, indicates Rafael Soares, researcher responsible for reaction tests of strains in Embrapa's soybean genetic improvement program. “In Brazil, plants with symptoms of the disease have already been found in the states of Rio Grande do Sul, Paraná, Santa Catarina, Mato Grosso do Sul, Minas Gerais, Goiás, Mato Grosso, Tocantins and São Paulo ”, adds Soares.

 “Fundação BA, Embrapa and partner institutions are intensifying research to determine which pathotypes of P.syae are present in the region, to enable more agility and precision in obtaining and indicating resistant cultivars adapted to the region”, explains researcher Geraldo Estevam de Souza Carneiro, from Embrapa Cerrados. “We are also intensifying research in partnership with producers, to implement control measures, in order to avoid the spread of the pathogen and the consequent losses for producers and the entire regional society”, comments Fabiano Jose Perina, from Embrapa Algodão.

The occurrence of the disease was registered in the Occurrence Registration System of the State Association for Agricultural Defense of Bahia (ADAB), an institution that will collaborate in the collection and registration of new cases of this disease in the state. The joint alert from Fundação Bahia and Embrapa to producers is available on link.