Quantificação de componentes monocíclicos da mancha angular do feijoeiro

Monocyclic components of angular leaf spot, were quantified on two bean (Phaseolus vulgaris) cultivars Rosinha and Carioca in growth chambers. Incubation period, disease severity and lesion growth rate were assessed, at temperatures of 6, 10, 14, 17, 21, 25, 29 and 33 oC. No angular leaf spot symptoms occurred at 6 and 29 oC. Severity for angular leaf spot was high between temperatures of 20 and 25 oC, and the incubation period for both varieties tested was favoured at a temperature of 25 oC. This temperature also provided the greatest lesion growth rate and these data were adjusted by a first grade equation in function of the temperature. The effect of the leaf wetness duration (5, 6, 12, 18, 24, 30, 36, 42, 48 and 54 h) in the severity of disease symptoms was studied as well. Severity for the angular leaf spot increased with the wetness duration period to the maximum of 54 h tested. The variations of angular leaf spot in relation to the number of hours of leaf wetness were explained by the Richards model. The Beta-Richards function explained the combined effects of the temperature and leaf wetness duration in the severity of angular leaf spot, for both varieties.