First report of spinach downy mildew caused by race Pfs:8 of Peronospora farinosa f. sp. spinaciae in Japan.

The race of field isolates of Peronospora farinosa f. sp. spinaciae (Pfs), causal agent of spinach downy mildew, were identified using race-differential cultivars. One isolate was similar to race Pfs:6. Three isolates were identified as race Pfs:8, the first time the race has been reported in Japan as far as we know. The differential reaction caused by the other two isolates did not match any known to be caused by races Pfs:1 through Pfs:11; thus, this strain appears to a new pathogenic strain in Japan.