Occurrence of Phytophthora clandestina races across rainfall zones in south-west Western Australia

Cultivars of subterranean clover (Trifolium subterraneum), Meteora and Denmark, sown in high rainfall zones in Western Australia were unique in their sensitivity to races of Phytophthora clandestina. The majority and most diverse of P. clandestina races occurred in the 700-1000 mm rainfall zone. Race 173 occurred across all rainfall zones >= 300 mm and race 177 in all zones >= 400 mm. Cultivar Denmark was highly resistant to races 001, 101, 141, 151 and 143, and moderately resistant to race 121, whereas cv. Meteora was highly resistant to race 151, moderately to highly resistant to races 001 and 101 and moderately resistant to races 121, 141 and 143. These differences are important in relation to the selection and breeding of cultivars for specific regions of Western Australia where particular races occur.