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Disease Note. First Report on Formation of Sclerotia of Claviceps purpurea on Bermudagrass (Cynodon dactylon). K. E. Conway, Department of Plant Pathology, Oklahoma State University, Stillwater 74078. C. M. Taliaferro, and R. A. Shelby. Department of Agronomy, Oklahoma State University, Stillwater 74078; and Department of Plant Pathology, Auburn University, Auburn, AL 36849. Plant Dis. 76:1077. Accepted for publication 2 July 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-1077E. The formation of honeydew on bermudagrass (Cynodon dactylon
(L.) Pers.) by Claviceps purpurea (Fr.:Fr.) Tul. has been reported
(1) and its anamorph has been isolated from bermudagrass, but
sclerotia have never been reported on that host. Cultures from bermudagrass
produce fluorescent alkaloid toxins in vitro and have been
implicated in the production of cattle tremors, but such toxins have
not been detected from the honeydew stage. Infection of bermudagrass
by the honeydew stage of C. purpurea was severe during the fall of
1991 throughout Oklahoma. Sclerotia were found on two breeding
lines and two plant introductions of bermudagrass near Stillwater,
Oklahoma, during October. Sclerotia were produced in 20-50% of
the seeds per head of line BERPC 91-6 but in <1-5% of those of
clone 9945 and the two plant introductions. Samples of infected seed
heads with sclerotia were extracted and analyzed by high-performance
liquid chromatography. Two toxins, ergotamine and an unknown
substance, were indicated by fluorescence detection, a technique that
denotes only fluorescent alkaloids, mainly ergopeptins, and not
clavines (2). The presence of sclerotia with toxic alkaloids in honeydewed
bermudagrass hay could pose a health threat to cattle. |