If we have a tendency to square measure to breed common bean (Phaseolus vulgaris L.) for sturdy resistance to diseases, we have a tendency to should perceive morbific variation and notice sources of resistance. Our initial objective was to figure out the patterns of morbific variation found among isolates of Phaeoisariopsis griseola (PG), the plant life that causes angular leaf spot (ALS) in common bean. we have a tendency to characterised 433 PG isolates from eleven occupant and ten African countries, victimization differential cultivars, isozymes, and/or random amplified polymorphic DNA (RAPD) markers. we have a tendency to additionally consistently screened, for ALS resistance, common bean accessions from the earth assortment control at CIAT, and assessed the progress up to now created in breeding for resistance to ALS. Despite their nice diversity among and between countries on each continents, the PG isolates were classified into to major groups: range, and Middle yankee. though every cluster had internal variations for virulence, and organic chemistry and molecular characteristics, the ‘Andean’ PG isolates were a lot of virulent on common beans of range origin, than on those of Middle yankee origin, thus, suggesting a host-pathogen co-evolution.