Angular leaf spot disease of common bean (Phaseolus vulgaris), caused by Phaeoisariopsis griseola, is one of the most important disease of this crop in Brazil. Control strategies for the disease include cultural practices, chemical control and genetic resistance. This pathogen is known to vary greatly in pathogenicity. For durable use of genetic resistance to control this disease, it is necessary to manage resistant cultivars by taking into account the population structure of P. griseola. Isolates of the pathogen from Goias, Brazil exhibited an important virulence polymorphism when inoculated on 12 differential cultivars. A total of 13 pathotypes was identified within a series of 96 isolates collected in Inhumas and Damolandia counties. Only pathotypes 63-15, 63-23, 63-31 and 63-63 were identified in both counties. Since all the isolates were capable of inducing disease in both Andean and Mesoamerican differential cultivars, they were considered to be of Mesoamerican origin. Random amplified polymorphic DNA (RAPD) analysis performed on the same 96 isolates revealed a great genetic diversity clustering the series into five groups at an Euclidean distance of 62.5%. Although the results did not show any clustering according to the isolate origin, it was possible to observe a tendency of the isolates to cluster in different groups according to their origin. No pathotype-specific band was observed in the present study.

Due to the increased importance of angular leaf spot of common bean (Phaseolus vulgaris) in Brazil, monitoring the pathogenic variability of its causal agent (Phaeoisariopsis griseola) is the best strategy for a breeding program aimed at developing resistant genotypes. Fifty one isolates of P. griseola collected in five Brazilian States were tested on a set of 12 international differential cultivars in the greenhouse. When inoculated plants showed symptoms but no sporulation was observed, they were transferred to a moist chamber for approximately 20-24 h. After this period of time, if no sporulation was observed, the plants were considered resistant; otherwise, they were considered susceptible. From the fifty-one tested isolates, seven different pathotypes were identified. No Andean pathotypes were identified; consequently, all isolates were classified as Middle American pathotypes. Pathotype 63-31 was the most widespread. Pathotype 63-63 overcame resistance genes present in all differential cultivars and also the resistance gene(s) present in the cultivar AND 277. This fact has important implications for breeding angular leaf spot resistance in beans, and suggests that searching for new resistance genes to angular leaf spot must be pursued.

The pathogenic variability was evaluated of 48 Pseudocercospora griseola isolates collected in the State of Minas Gerais, Brazil. Isolates were inoculated to a set of 12 international differential cultivars in a greenhouse. Ten pathotypes (55‐15, 63‐7, 63‐15, 63‐23, 63‐25, 63‐27, 63‐31, 63‐47, 63‐55 and 63‐63) were identified, showing the great pathogenic variability of this fungus in Minas Gerais State. Pathotypes 55‐15, 63‐15, 63‐25 and 63‐27 had not previously been reported in the State. Of the 48 isolates, all except pathotype 55‐1547 induced a compatible reaction with all cultivars from the Andean group. Isolates were highly pathogenic in both Andean and Mesoamerican cultivars, thus being classified as Mesoamerican pathotypes. Pathotype 63‐63 was the most widespread, and overcame the resistance genes present in all differential cultivars.

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Brazil in view of its erect growth habit, earliness, good lodging resistance and resistance to Colletotrichum lindemuthianum and to bean common mosaic virus.