Variation in Pathogenicity Among Isolates of Phytophthora dandestina

Studies on 25 isolates of Phvtophthora dandestina collected from four states in southern Australia identified the presence of diversity in pathogenicity but not in morphology among isolates. Race 0 was found in all states except New South Wales, race 1 was found in all states, and races 2 and 3 were found only in Victoria and New South Wales, respectively. Race 4 was identified in Victoria and Western Australia. There was no apparent change in pathogenicity of the fungus following 10 (every 20 days) or 20 (every 10 days) cycles of subculturing. There was also no shift towards higher aggressiveness or virulence during 10 cycles of the fungus through susceptible or resistant cuitivars