Aspectos epidemiológicos do mofo-branco e feijão comum

• Autor(a) principal: Santos, Priscila Ferreira dos
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/10448
• topic: Densidade de inóculo; Manejo integrado de doenças; Molhamento foliar; Phaseolus vulgaris; Sclerotinia sclerotiorum; Inoculum density; Integrated disease management; Leaf wetness; Phaseolus vulgaris; Sclerotinia sclerotiorum; AGRONOMIA::FITOSSANIDADE

To better understand the epidemiology of Sclerotinia sclerotiorum (Lib.) de Bary, causal agent of white mold on common beans (Phaseolus vulgaris L.) a field trial was carried out to assess the relationship between inoculum density before disease onset (apothecia), disease severity, yield and number of sclerotia formed after plant infection. The experimental field was set in Goianira, GO, with the sprinkle irrigated cropping of common bean cv. Pérola, and consisted of plots treated with chemical fungicide (fluazinam), biological control (Trichoderma harzianum) and integrated management of white mold (Trichoderma harzianum+Fungicide). Plots without any treatment were used as control plots. The results were submitted to analysis of variance and regression and, when necessary, to the Tukey's test (5%). The number of apothecia and number of new sclerotia formed after infection with S. sclerotiorum were related to disease severity and yield, by simple linear models. The integrated management obtained with chemical + biological control achieved better results than the separate application of control measures. The decrease of 35.3% to 0.9% severity of the disease, and 80% reduction in the number of new sclerotia were recorded for the integrated management treatments, in comparison to the control plots. From the sum of new sclerotia produced, 64% were recovered with the harvested grains, and 31% and 5% were respectively found on soil surface residue or after residue threshing. A second study aimed to estimate e the effects of temperature and leaf wetness on infection and development of S. sclerotiorum lesions. This second trial was carried out with ‘Jalo Precoce’ common bean plants. After inoculation with flowers previously colonized by the pathogen’s mycelium, the trial was set under controlled conditions. To assess the incubation period and lesion size in leaves, the inoculated plants were submitted to temperatures of 10°, 15°, 20°, 25° and 30°C and leaf wetness periods (LWP) of 4, 8, 12, 16, 20, 24 and 28h, under a 12h photoperiod. Temperatures of 20° to 25°C, in combination with LWP of at least 12 hours favored infection of ‘Jalo Precoce’ plants by S. sclerotiorum. Plants were infected at 10°C, but did not develop symptoms in the studied time intervals.