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Disease Note

Foliar Blight of Cynodon spp. Forage Caused by Rhizoctonia solani in Florida. R. M. Sonoda, University of Florida IFAS Agricultural Research and Education Centers, Ft. Pierce 33454. P. Mislevy, Ona, FL 33865. Plant Dis. 69:811. Accepted for publication 27 May 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-811e.

A severe foliar blight of Cynodon spp. forage (bermudagrass, stargrasses, and various hybrids) was observed in pastures in Ona, Florida, during August and September 1983. Rhizoctonia solani Kühn Ag-1 was consistently isolated from lesions. Potted plants of Cynodon spp. were inoculated with the fungus, and Koch’s postulates were confirmed. Where cattle were grazed at 2-, 4-, 5-, and 7-wk intervals on replicate pastures containing seven Cynodon spp., the percentage of affected foliage on the most susceptible cultivar. Callie hybrid (C. dactylon (L.) Pers. var. dactylon [Tifton 44] × C. dactylon var. aridus Harlan et de Wet [Callie]), was 16.6, 0, 53.3, and 86.2, respectively. Foliar blight was not detected on the C. dactylon × C. nlemfuensis Vanderyst hybrid, Tifton 72-81. The other five Cynodon spp. were lightly affected at the 2- and 4-wk grazing intervals and moderately to severely affected at the 7-wk interval. The incidence of foliar blight decreased after October 15 on each affected cultivar. Cattle grazed R. solani-affected Cynodon spp. forage with no signs of rejection.