Survey of Phytophthora infestans populations in Serbia: mating type, metalaxyl resistance and virulence properties

A total of 37 single-lesion isolates of Phytophthora infestans were collected during 2000 from different potato growing regions in the central part of Serbia. They were paired in A1 and A2 matings to determine their mating types. Of these 37 isolates, 28 were found to belong to the A2 mating type, eight to the A1 type and one was found to be self-fertile (A1/A2). Using the in vitro mycelial radial growth method no metalaxyl resistant P. infestans isolate could be found. The rate of occurrence of intermediate isolates was not high, on the average 2.70%. All other isolates were sensitive to metalaxyl. There was no correlation between mating type and the intermediate metalaxyl resistance found.