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Occurrence of Fusarium Stalk Rot on a Supersweet Corn Cultivar in Oklahoma. V. M. Russo, USDA-ARS, South Central Agricultural Research Laboratory, POB 159, Lane, OK 74555. C. L. Patterson, Wes Watkins Agricultural Research and Extension Center, Oklahoma State University, POB 128, Lane 74555. Plant Dis. 75:862. Accepted for publication 1 April 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0862C.

Stalks of supersweet corn (Zea mays L. var. rugosa Bonaf. 'Florida Staysweet') grown in Lane, Oklahoma, were periodically collected (from about 14 days before tasseling through harvest) and split longitudinally. Purple discoloration was consistently associated with nonvascular tissue in the nodes, but no symptoms were noted on external tissues and symptoms did not develop further in internal stalk tissues. Fusarium moniliforme J. Sheld., incitant of Fusarium stalk rot (1), was isolated from affected nodal tissues. An ice pick drawn across the surface of F. moniliforme colonies obtained from infected field plants was inserted into the second to fourth nodes of Florida Staysweet plants (six-node stage) grown in a greenhouse, then withdrawn. The wounded areas were secured with Parafilm. Wounded, uninoculated plants served as controls. F. moniliforme was verified as the pathogenic organism because symptoms identical to those observed in the field developed on inoculated plants and F. moniliforme was reisolated from infected tissue. This is the first confirmed diagnosis of the disease on sweet corn in Oklahoma. Infection with F. moniliforme reduces germination of kernels of some sweet corn genotypes (2). Factors inhibiting development of F. moniliforme in Florida Staysweet may be related to the cultivar's lack of susceptibility to the four-leaf dieback syndrome that affects some sweet corn sh2 genotypes.

References: (1) D. C. Foley. Phytopathology 52:870, 1962. (2) J. M. Headrick and J. K. Pataky. Plant Dis. 73:887, 1989.