First Report of Phytophthora infestans Self-Fertile Genotypes in Southern Brazil

During the autumn of 2011 and 2012, leaf and stem samples of potato plants infected with P. infestans were collected in southern Brazil. Monosporangial isolates of P. infestans were obtained from the samples and mating types were determined. Each isolate was paired with the A2 and A1 mating types of P. infestans and self-paired on Petri plates containingV8 juice agar. After this, the plates were kept at 18°C in darkness for 20 days. Three isolates collected in Parana State (municipalities of Ponta Grossa 25°12′26″S, 50°07′11″W; Contenda 25°38′52″S, 49°34′26″W; and Castro 24°51′50″S, 49°53′50″W) formed oospores when paired with both mating type isolates and also when self-paired.