Cross-Resistance to Four Systemic Fungicides in Metalaxyl-Resistant Strains of Phytophthora infestans and Pseudoperonospora cubensis. Yigal Cohen, Professor, Department of Life Sciences, Bar-Ilan University, Ramat-Gan 52 100, Israel. Yair Samoucha, Research Assistant, Department of Life Sciences, Bar-Ilan University, Ramat-Gan 52 100, Israel. Plant Dis. 68:137-139. Accepted for publication 16 August 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-137.

Although cyprofuram + folpet, SAN 371F, propamocarb, and phosethyl Al controlled metalaxyl-sensitive strains of Phytophthora infestans and Pseudoperonospora cubensis in potato and cucumbers, respectively, the fungicides failed to do so in plants inoculated with metalaxyl-resistant strains.