Escala diagramática para avaliação da severidade da antracnose das vagens de Feijão-Fava: desenvolvimento e validação

Abstract

Anthracnose is an more important disease of Lima bean (Phaseolus lunatus L.), caused by the fungus Colletotrichum truncatum (Schwein), responsible that significant yield losses. The symptom occurs in the hypocotyl, ribbed leaf, stem, petioles and pods. The pods symptom of anthracnose in Lima bean is easier to be observed, with depressed lesions, large and red. However, is necessary to standardize the quantification of disease to adopt a control strategy. Up until then the anthracnose severity in Lima bean is evaluated using a scale developed for common bean pods (Phaseolus vulgaris L.), however this scale is inefficient in the quantification of anthracnose in this culture, because levels severity, 1.5, 6, 11, 21 and 34% has been well below the levels observed in Lima Bean Pods, necessitating the development of a specific scale. Therefore this study aimed at the development and validation of diagrammatic scale to assess the severity of anthracnose of Lima Bean Pods. According to morphological distribution of the lesions observed in the pods photographed, was established a diagrammatic featuring eight levels of severity, 3, 6, 12, 24, 48, 68, 84 and 96%. The levels of repeatability and reproducibility of measurements of the severity of anthracnose in Lima Bean Pods using the scale developed improved significantly relative to the scale of the common bean, justifying its use in epidemiological studies and providing more accurate information about the assessment of this disease.