Response of Soybeans and Soybean Pathogens to Soil Fumigation and Foliar Fungicide Sprays. D. R. Kittle, Research Associate, Agricultural Research Service, U.S. Department of Agriculture, and Department of Plant Pathology, University of Illinois, Urbana 61801. L. E. Gray, Research Plant Pathologist and Associate Professor, Agricultural Research Service, U.S. Department of Agriculture, and Department of Plant Pathology, University of Illinois, Urbana 61801. Plant Dis. 66:213-215. Accepted for publication 13 May 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982. DOI: 10.1094/PD-66-213.

Soil fumigation with sodium methyldithiocarbamate (metham sodium) and foliar fungicide sprays with methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate (benomyl) were effective in controlling the major soybean pathogens encountered in this study. Fumigation reduced populations of Macrophomina phaseolina in residue and of M. phaseolina, Mycoleptodiscus terrestris, and Fusarium spp. in roots. Fumigation also reduced vascular discoloration in stem and roots and increased infection rate of Septoria glycines on leaves compared with check plots. Fungicide sprays reduced brown spot severity and S. glycines infection rate. Spraying also reduced sporulation on pods and stems of Phomopsis sojae, reduced vascular discoloration in root and stems, reduced rate of leaf loss, and increased seed quality compared with control plots. During 3 yr, neither treatment consistently increased yield. When the soil fumigation and fungicide spray treatments were combined, however, there was a large yield increase, averaging 26%, compared with the untreated control.

Keyword(s): Phialophora gregata.