Interaction Between Bacillus subtilis and Fungi Associated with Soybean Seeds. M. A. Cubeta, Former Graduate Research Assistant, Department of Plant Pathology, University of Illinois at Urbana-Champaign, Urbana 61801. G. L. Hartman, Assistant Plant Pathologist, and J. B. Sinclair, Professor, Department of Plant Pathology, University of Illinois at Urbana-Champaign, Urbana 61801. Plant Dis. 69:506-509. Accepted for publication 3 December 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-506.

A Bacillus subtilis isolate from soybean was tested for antagonism against 26 fungi commonly associated with soybean seeds in dual culture on potato-dextrose agar (PDA) and soil-extract agar. The bacteria were fungicidal to Penicillium sp. and fungistatic to all others. Autoclaved filtrates of B. subtilis cultures inhibited growth and stroma formation of Phomopsis sp. A chloroform-soluble component from autoclaved B. subtilis culture filtrates was active against seven soybean pathogens on PDA. Suspensions of B. subtilis applied as a soybean seed treatment reduced stem infection caused by Phomopsis sp., emergence, and plant height in the field but not in greenhouse or growth chamber studies. Suspensions of B. subtilis sprayed on soybean plants significantly reduced Phomopsis pod infection in a growth chamber but not in the field.

Keyword(s): pod and stem blight.