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Disease Note.

First Report of Leptosphaerulina briosiana on Soybean in Missouri. S. M. Rosenbrock, Department of Plant Pathology, Extension Agronomy, University of Missouri, Columbia 65211. B. S. Lucas, E. W. Palm, and T. D. Wyllie, and R. G. Hoormann. Department of Plant Pathology, and Extension Agronomy, University of Missouri, Columbia 65211. Plant Dis. 72:268. Accepted for publication 12 October 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0268F.

In July 1986, symptoms similar to those descirbed for sudden death syndrome appeared on four soybean (Glycine max(L.) Merr.) cultivars (Williams 82, Asgrow 3427 and 3966, and Challenger) in five northeast Missouri fields. Perithecioid pseudothecia containing asci and ascospores of the genus Leptosphaerulina were consistently isolated from necrotic leaf tissue. Fungus cultures grown on v-8 juice agar devolped ascocarps 100x185 µm). Ascospores corresponded to those of L. briosiana (Poll.) Graham & Luttrell (1,2). Koch's postulates were satisfied in the greenhouse on soybean cultivar Williams 82. Lesions were purplish circular spots that eventually formed gray-tan necrotic centers containing black pseudothecia. This is the first report of this disease in the intensive soybean production area of the midwest and only the second report on soybean production area of the Midwest and only the second report on soybean in the United States(the other was in Maryland [2]). The large geographic seperation between reported occurences of the disease should alert plant pathologists that the organism is probably widespread but has remained unrecognized.

References: (1) J.H Graham and E.S Luttrell. Phytopahtology 51:680, 1961. (2) A.P Grybauskas. Plant Dis. 70:1159, 1986.