Cercospora leaf spot, caused by Cercospora cruenta, is an important phytopathological problem of the cowpea (Vigna unguiculata) crop, which genetic resistance provides the most effective control. Thus, knowing the inherintance type is essential to the improvement of resistance for this disease. This work was carried out under field conditions, utilizing the L101000-1 line and the cultivar IPA 206 as parents, the two being considered resistant and susceptible, respectively. Parent plants were crossed using the flower emasculation technique to obtain F1, F2 and F3 populations. Parent plants and segregate generations were inoculated, at 20, 27 and 34 days after planting. A conidial suspension 4x10³ spores/ml was prepared from typical lesions of the disease on leaf surfaces. An evaluation of the symptoms, based on susceptible or resistance reactions was perfomed on individual plants 75 days after planting. The plants of the L101000-1 line and F1 populations showed resistance while the cultivar IPA 206 showed typical symptoms of Cercospora leaf spot. In the F2 generation, from the 132 plants observed, 105 were resistant and 27 susceptible; in the F3 generation, from the 90 plants evaliated, 70 were resistant and 20 susceptible. These results were analyzed by the Chi-square test and suggest that the inheritance of resistance to Cercospora cruenta, in the L101000-1 line, is the monogenic and dominant type.
