VIEW ARTICLE

Physiology and Biochemistry

Influence of Four Herbicides on Carpogenic Germination and Apothecium Development of Sclerotinia sclerotiorum. W. L. Casale, Graduate research assistant, Department of Botany and Plant Pathology and Pesticide Research Center, Michigan State University, East Lansing 48824; L. P. Hart, associate professor, Department of Botany and Plant Pathology and Pesticide Research Center, Michigan State University, East Lansing 48824. Phytopathology 76:980-984. Accepted for publication 27 March 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-980.

Mycelial growth of Sclerotinia sclerotiorum on agar was inhibited by metribuzin and diuron at 50 μg/ml. The number of sclerotia that produced stipes was reduced by these compounds at 100 μg/g in soil; apothecia that did develop appeared normal and produced ascospores. Atrazine and simazine were less inhibitory to mycelial growth and had no effect on the number of sclerotia producing stipes, even at 10 mg/g soil. In the presence of atrazine or simazine, however, apothecia either did not develop from the stipes or were abnormally shaped and produced no ascospores. Abnormal apothecia formed in soil amended with atrazine (4-500 μg/g) or in solutions of 2-50 μ M atrazine. When normal immature apothecia grown in the absence of atrazine were soaked in 50 μM atrazine for 30 min, the hymenia aborted and each gave rise to new stipes. This study indicates a potential use of triazines for investigating apothecial differentiation in S. sclerotiorum.