Studies on Alternate Hosts of the Rust Puccinia canaliculata, a Potential Biological Control Agent for Nutsedges. M. B. Callaway, Graduate Student, Horticulture Department, Coastal Plain Experiment Station, Tifton, GA 31793. S. C. Phatak, Professor, Horticulture Department, Coastal Plain Experiment Station, and H. D. Wells, Plant Pathologist, USDA, Coastal Plain Experiment Station, Tifton, GA 31793. Plant Dis. 69:924-926. Accepted for publication 4 April 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1985. DOI: 10.1094/PD-69-924.

Puccinia canaliculata is a potential biological control agent for purple (Cyperus rotundus) and yellow (C. esculentus) nutsedges. In 1905, Xanthium canadense L. was shown to be an alternate host for P. canaliculata. After extensive surveys, the aecial stage has not been found occurring naturally on X. strumarium in Georgia. Inoculation studies demonstrated that X. strumarium and Helianthus annuus are alternate hosts. Inoculation studies were also carried out on Cosmos bipinnatus with inconclusive results. Inoculations on alternate hosts may offer a simple method for developing more universally virulent rust strains to overcome variations in susceptibility among nutsedge ecotypes.