VIEW ARTICLE

Sclerotinia homoeocarpa Tolerance to Benzimidazole Configuration Fungicides. Clifford G. Warren, Graduate Student and Research Aide, Department of Plant Pathology, The Pennsylvania State University, University Park 16802; Patricia Sanders(2), and Herbert Cole(3). (2)(3)Part-time Research Associate, and Professor, respectively, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Phytopathology 64:1139-1142. Accepted for publication 23 March 1974. DOI: 10.1094/Phyto-64-1139.

Isolates of Sclerotinia homoeocarpa were collected during 1972 from locations in the eastern and midwestern U.S. where benomyl had failed to control Sclerotinia dollar spot on turfgrass. Isolates from such locations were comparable in cultural morphology and disease symptom development to nontolerant isolates of S. homoeocarpa. On fungicide-amended PDA, isolates from control failure locations were over 100 times as tolerant to benomyl as isolates from other areas. Tolerance to benomyl was associated with tolerance to several other benzimidazole configuration fungicides. No tolerance was detected for Actidione or chlorothalonil. Moderate tolerance to Dyrene was noted with one isolate. In greenhouse experiments with Penncross creeping bentgrass, neither benomyl nor Bay Dam 18654 suppressed infection by tolerant isolates. Actidione and Dyrene were partially effective in controlling both tolerant and nontolerant isolates.