Pathogenicity to wheat and rye of Pseudocercosporella herpotrichoides isolates from France and the UK

Isolates of Pseudocercosporella herpotrichoides from France and the U.K. were tested for pathogenicity to wheat and rye seedlings in parallel controlled-environment experiments in both countries. There was no difference in pathogenicity to wheat or rye seedlings between isolates from France and isolates from the U.K., but both groups of isolates generally penetrated more seedling leaf sheaths in French than in U.K. experiments. Both W-type and R-type groups of isolates were more pathogenic to wheat than to rye, but W-type isolates were generally more pathogenic to wheat than were R-type isolates, and R-type isolates were generally more pathogenic to rye than were W-type isolates. There were large differences in pathogenicity to wheat or rye among isolates in each group, but pathogenicity to wheat did not appear to be related to pathogenicity to rye for either W-type or R-type isolates. There were no differences in pathogenicity between carbendazim-resistant and carbendazim-sensitive isolates.