Abstract
The american bean powdery mildew seems to be very virulent in the West Indian area. Resistant lines have been found in Haiti, such as "Kenscoff I", "Salagnac 86", "Salagnac 131". Borlotto nano Vigevano" was used as susceptible check. The study of the progeny from crosses between these cultivars allowed to distinguish two components of the resistance obtained from Haitian lines: "seedling resistance", induced by a dominant gene, and "adult plant resistance", which seems polygenic recessive.