Pathogenicity to Wheat of Isolates of Pseudocercosporella herpotrichoides (Fron) Deighton from Five Graminaceous Hosts

Abstract Eleven isolates of Pseudocercosporella herpotrichoides were obtained from field material of the Gramineae Agropyron repens, Alopecurus myosuroides, Apera spica‐venti, Hordeum vulgare and Triticum aestivum. Four of these isolates belonged to the variety acuformis and 7 isolates to the variety herpotrichoides of the fungus. In a greenhouse experiment, winter wheat was inoculated with these isolates. All isolates were pathogenic on wheat. They differed in virulence, but these differences could not be related to the nature of their original hosts nor to their classification as variety acuformis or herpotrichoides.