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Disease Control and Pest Management

Efficacy of Polyethyleneglycol and Organic Solvents for Infusing Fungicides into Soybean Seeds. B. J. Shortt, Graduate research fellow, Department of Plant Pathology, University of Illinois, Urbana 61801; J. B. Sinclair, professor, Department of Plant Pathology, University of Illinois, Urbana 61801. Phytopathology 70:971-973. Accepted for publication 31 March 1980. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-971.

Soybean (cultivar Bonus) seeds treated with one of six contact or six systemic fungicides in acetone, dichloromethane (DCM), or aqueous polyethyleneglycol (PEG) were assayed for fungicide activity. Activity was detected in seeds treated with the systemic fungicides benomyl, carboxin, sisthane, and thiabendazole. Solubility of the fungicides in the solvents was not related to uptake by the seeds. Benomyl, sisthane, and thiabendazole were detected in seeds treated with acetone, DCM, or PEG, however, carboxin was detected only in seeds treated with PEG. Larger inhibition zones and a greater reduction of seedborne Phomopsis sp. occurred when benomyl and sisthane were infused with PEG than with either acetone or DCM. No treatment was 100 percent effective. Acetone and, to a greater extent, DCM killed Phomopsis sp. borne within the seedcoat, however, they damaged exposed cotyledonary tissues. Increased cotyledonary damage was associated with increased recovery of Bacillus subtilis. The efficacy of any treatment depended on the fungicide and solvent-carrier combination.