Aspectos epidemiológicos do mofo-branco e feijão comum
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2013-03-26
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Universidade Federal de Goiás
Resumo
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.
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SANTOS, Priscila Ferreira dos. Aspectos epidemiológicos do mofo-branco e feijão comum. 2013. 71 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2013.