AGUIAR, F. M.

LOPES, C. A.

SILVA, B. C.

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Outbreak of Cylindrocladium gracile associated with potato tuber rot.

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Tropical Plant Pathology 37 (Suplemento), agosto 2012 45º Congresso Brasileiro de Fitopatologia - Manaus, AM Copyright the Brazilian Phytopathological Society  htpp://www.sbfito.com  MICOLOGIA  531  Outbreak of Cylindrocladium gracile associated with potato tuber rot. (Surto de Cylindrocladium gracile associado com podridão de tubérculo de batata.)  Aguiar, F.M.1, Lopes, C.A.2, Silva, B.C.3 1Doutorando em Fitopatologia da UnB, 2Pesquisador da Embrapa Hortaliças, 3Graduando em Agronomia da UnB. E-mail: frederick@cnph.embrapa.br.    The pathogenicity of Cylindrocladium. gracile (= C. clavatum) to potato was described in 1980 as superficial tuber spots associated with wounds and lenticels. Since then, the disease has been observed with frequency as post-harvest blemishes known as brown eye, especially in potatoes grown in the rainy season in the Cerrado soils of Central Brazil. Losses, however, were usually neglected to cosmetic importance, as shallow lesions restricted to lenticels concentrated at the stolon end of the tubers. In the summer of 2011, commercial fields of ‘Agata’ from in Ibicoara, BA, were heavily affected by a tuber rot with losses estimated in 40%.  Symptoms of the disease resembled the field phase of dry rot caused by species of Fusarium. Isolations on PDA from the border of internal tissue of partially rotted tubers yielded white Fusarium-like mycelia and cream mycelia with dark brown pigment, typical of C. gracile.  Pathogenicity tests with the isolated fungi were performed on potato tubers of ‘Agata’. Portions of four-day old colonies from PDA agar plates were removed with a sterile wood toothpick, which was immediately introduced into surface sterilized tubers, which were then kept in a moist chamber for two days. Only C. gracile colonies were pathogenic, forming deep dark rotting on the tuber pulp after four days. Reisolation from the rotted areas yielded colonies with the same characteristics of the inoculated ones.  This is apparently the first report of potato tuber rot caused by C. gracile in Brazil associated with heavy yield losses in a commercial field and is an alert of a new threat to the local potato industry.  Apoio: CNPq, FAPDF. 

http://www.alice.cnptia.embrapa.br/alice/bitstream/doc/943701/1/Fito45Congress531.pdf

Outbreak of Cylindrocladium gracile associated with potato tuber rot.

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