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Macrophomina phaseolina, Another Cause of the Twin-Stem Abnormality Disease of Soybean. P. R. Bristow, Washington State University, Western Washington Research and Extension Center, Puyallup 98371. T. D. Wyllie, Department of Plant Pathology, University of Missouri, Columbia 65211. Plant Dis. 70:1152-1153. Accepted for publication 22 July 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-1152.

Symptoms of the twin-stem abnormality disease were observed on seedlings of eight of 14 genotypes when apparently healthy seed was sown in vermiculite infested with Macrophomina phaseolina. Infected genotypes were Adelphia, Amsoy-71, Calland, Clark-63, Hill, Mandarin, Mukden, and Williams. Disease incidence ranged from 7 to 45%. The genotypes A-100, A.K. (Harrow), Beeson, Cutler, Dunfield, and PI 92-964 did not show the twin-stem symptom and were apparently resistant. This abnormality disease, though reported to be caused by Sclerotium sp., may be a general response when seedlings are infected by several seedborne or soilborne pathogens.

Keyword(s): charcoal rot, microsclerotia.