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Pathogenicity of Rhizoctonia Solani to Aquatic Plants. B. G. Joyner, Graduate Research Assistant, Plant Pathology Department, University of Florida, Gainesville 32601; T. E. Freeman, Professor, Plant Pathology Department, University of Florida, Gainesville 32601. Phytopathology 63:681-685. Accepted for publication 12 December 1972. DOI: 10.1094/Phyto-63-681.

A Rhizoctonia solani isolate (RhEa) from diseased anchoring hyacinth (Eichhornia azurea) in Panama was pathogenic to several aquatic plants, particularly to water hyacinth (E. crassipes) and water lettuce (Pistia stratioites). Penetrating hyphae of RhEa grew from infection cushions through the stomates of water hyacinth leaves. Only the emersed portions of water pennywort (Hydrocotyle umbellata) and water hyacinth were infected by RhEa. Another R. solani isolate (14011) infected both submersed and emersed portions of these two plants. Disease, caused by RhEa, in water hyacinth was severe at 28 C, but as temperature was increased to 32 C, disease severity decreased and little or no damage was detected. Disease severity in water hyacinth caused by another R. solani isolate (H287) was the same at both 28 and 32 C.