VIEW ARTICLE

Disease Control and Pest Management

Effects of Chlorothalonil on the Virulence and Physiology of a Nontargeted Pathogen, Sclerotinia minor. F. C. Hau, Graduate research assistant, Department of Plant Pathology, North Carolina State University, Raleigh 27650; M. K. Beute, professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650. Phytopathology 73:475-479. Accepted for publication 4 October 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-475.

Inoculum of Sclerotinia minor produced in the presence of 0.2- 0.4 μg of chlorothalonil (CTL) per milliliter induced larger stem lesions on peanut after 24 hr of incubation than did inoculum similarly produced in the absence of the fungicide. Lesions induced by S. minor inoculum grown in the presence of 0.2 μg of CTL per milliliter released more electrolytes into a bathing solution than lesions induced by S. minor inoculum grown without fungicide present. Four-day-old cultures of S. minor amended with 0.2 μg of CTL per milliliter yielded filtrates that contained more oxalic acid than did otherwise similar culture filtrates from cultures grown without the fungicide. Low concentrations (0.2- 0.8 μg/ml) of CTL consistently inhibited the production of pectolytic enzymes by S. minor in cultures.