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Cultural Studies on Dactuliochaeta glycines, the Causal Agent of Red Leaf Blotch of Soybeans. G. L. Hartman, Plant Pathologist, Asian Vegetable Research and Development Center, P.O. Box 42, Shanhua, Tainan, Taiwan 74199, R.O.C.. J. B. Sinclair, Professor, Department of Plant Pathology, University of Illinois at Champaign-Urbana, 1102 S. Goodwin Ave., Urbana 61801-4709. Plant Dis. 76:847-852. Accepted for publication 7 March 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0847.

Sclerotia of Dactuliochaeta glycines were isolated from leaf lesions of soybeans (Glycine max), a wild perennial relative (Neonotonia wightii) of soybeans, and soil. Recovery of sclerotia from soybean field soil ranged from three to 19 sclerotia per gram of dry soil. More than 90% of sclerotia germinated at 5 C after 18 mo, and more than 22% germinated when incubated at 100 C for 120 min. Pycnidiospore germination was optimal at 20 and 25 C. Pycnidiospores did not germinate after incubation for 12, 24, or 36 hr at 5 or 35 C. In culture, the fungus produced sclerotia on substrates with organic nitrogen sources, oat and wheat seeds, wood, and detached leaves of some legume species. Pycnidia and sclerotia were produced abundantly on media containing asparagine or casein hydrolysate, respectively. Pycnidia did not fully develop on culture media with greater than 1% sodium chloride. Inoculated leaf disks of 10 Glycine species and six other leguminous plants were infected, and on some species, typical lesions, pycnidia, and sclerotia developed.