Soybean Seed Thermotherapy with Heated Vegetable Oils. M. M. Pyndji, Former Graduate Student, Department of Plant Pathology, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Avenue, Urbana 61801. J. B. Sinclair, and T. Singh. Professor, and Former Visiting Research Associate, Department of Plant Pathology, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Avenue, Urbana 61801. Plant Dis. 71:213-216. Accepted for publication 18 September 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0213.

Refined maize (Zea mays), palm (Eleais guinensis), soybean (Glycine max), and sunflower (Helianthus annuus) oils were evaluated as a medium for heating soybean seeds to control the seedborne fungi Alternaria spp., Cercospora kikuchii, and Phomopsis spp. Seeds of five cultivars with a moisture content 7.5% or lower ranging in age from 6 to 24 mo were treated in one of the heated oils from 2 to 15 min at 80 or 90 C. All treatments significantly (P = 0.05) reduced recovery of the three fungi below that of the controls. C. kikuchii was eradicated after 5 min at 90 C, but Alternaria spp. were not. There was a concomitant increase in germinable seeds with decreased recovery of Phomopsis spp. Heat treatment was more effective in seeds less than 1 yr old than in those more than 1 yr old. No heat treatment affected seed germination in the laboratory. Emergence was significantly reduced by heat treatment in the greenhouse for seeds more than 1 yr old but not for seeds 1 mo old. Emergence was reduced by heat treatment below that in the control in the field, but yield was unaffected.