Application of the detached-leaf technique to evaluate the pathogenicity of isolates of fungi Ascochyta fabae and Botrytis fabae to faba bean

Abstract

The most important diseases of the faba bean include Ascochyta blight caused by the fungus Ascochyta fabae and chocolate spot caused by the fungus Botrytis fabae. The pathogenicity of isolates of A. fabae and B. fabae was investigated  to six cultivars of faba bean. The technique of detached leaves was used. The leaves were inoculated with pycnidial and conidial spores of the pathogens tested. After incubation, the sizes of necrotic spots produced by pathogens were determined. Significant variation in the pathogenicity of isolates of both fungi was found. The varieties showed differential resistance to Ascochyta blight and chocolate spot. The variation in resistance of cultivars to chocolate spot was lower than resistance to Ascochyta blight. The possibility of using the ImageJ image analysis software to measure the surface of necrotic spots was described.