Effect of Three Desiccant-Type Herbicides on Fruiting Structures of Colletotrichum truncatum and Phomopsis spp. on Soybean Stems. R. F. Cerkauskas, Former Graduate Research Assistant, Department of Plant Pathology, University of Illinois at Urbana-Champaign, Urbana 61801. O. D. Dhingra, Department of Plant Pathology, Universidade Federal de Viçosa, Viçosa, Minas Gerais, 36.570 Brazil; and J. B. Sinclair, Department of Plant Pathology, University of Illinois at Urbana-Champaign, Urbana 61801. Plant Dis. 67:620-622. Accepted for publication 15 November 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-620.

Soybean (Glycine max) cultivars UFV₁ and UFV₂ grown at Florestal and Viçosa, Brazil, and cultivars Bonus and Wells grown at Urbana, IL, were sprayed at growth stages R5.5–6 (full pod) or R7 (physiologic maturity) with one of three desiccant-type, nonselective herbicides: glyphosate, paraquat, or sodium chlorate:sodium borate (50:50). The stems of all paraquat-sprayed plants had optimum development of fruiting structures of Colletotrichum truncatum, causal fungus of soybean anthracnose, and of Phomopsis spp., causal fungi of soybean pod and stem blight, stem canker, and seed decay as much as 3 wk earlier than unsprayed plants. Glyphosate-sprayed plants of Bonus and UFV₁ gave similar results. No differences were noted between plants unsprayed or sprayed with sodium chlorate:sodium borate. Parallel increases in the development of fruiting structures with time were recorded on stems of unsprayed and sprayed plants. Treatment, time of treatment, and location influenced the development of the fruiting structures of the test fungi.