Pseudocercospora griseola, the causal agent of common bean angular leaf spot: Strain characterization and sensitivity to fungicides

Abstract

Angular leaf spot (ALS), a typical disease in common beans (Phaseolus vulgaris), is caused by the fungus Pseudocercospora griseola (Singh & Schwartz, 2010). Conidia are mainly spread by wind; however, water droplets, agricultural implements and contaminated seeds also facilitate pathogen transmission. The optimum conditions for infection include humidity and a temperature of 24°C. The conidia can germinate in about 3 h, penetrating the leaves through the stomata within 2 days. The whole tissue is colonized by the pathogen after 3-7 days and lesions can be observed 8-15 days after infection. Symptoms of ALS appear primarily on leaves and pods (Liebenberg & Pretorius, 1997). The lesions may coalesce, causing premature defoliation that compromises pod