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Disease Note 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withdrawn.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. |