Powdery Mildew Pustules Supporting Fusarium culmorum Infection of Wheat Leaves. A. Mathis, Institute of Phytomedicine, Universitätstrasse 2, Swiss Federal Institute of Technology, 8092 Zurich. H. R. Forrer, Swiss Federal Research Station for Agronomy, Zurich-Reckenholz; and C. Gessler, Institute of Phytomedicine, Universitätstrasse 2, Swiss Federal Institute of Technology, 8092 Zurich. Plant Dis. 70:53-54. Accepted for publication 19 June 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-53.

In greenhouse experiments, powdery mildew on wheat leaves was stopped 6 days after inoculation by a root application of benomyl. Three days after benomyl application, the plants were inoculated with a benomyl-tolerant mutant of Fusarium culmorum. Thus, the fungus was able to establish itself on the leaves, whereas neither wild-type nor mutant strains could infect healthy (powdery mildew-free) leaves. It is concluded that powdery mildew pustules allow F. culmorum to infect wheat leaves.