Number, Viability, and Buoyancy of Rhizoctonia solani Sclerotia in Arkansas Rice Fields. Fleet N. Lee, Assistant Professor, Department of Plant Pathology, Rice Branch Experiment Station, University of Arkansas, Stuttgart 72160. Plant Dis. 64:298-300. Accepted for publication 26 November 1979. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-298.

The number, viability, and buoyancy of sclerotia produced by Rhizoctonia solani, cause of rice sheath blight, in severely affected rice fields were studied. Samples (1 L) of crop debris to a 0.6 cm depth contained 136–562 buoyant and 68–334 nonbuoyant sclerotia. Viability of buoyant and nonbuoyant sclerotia varied from 41.1 to 60.8% and 25 to 55.6%, respectively. Samples from 0.6–3.8 cm contained 38–63 buoyant and 5–24 nonbuoyant sclerotia per liter of soil. Soil 3.8–7.6 cm deep contained 27–44 buoyant and 0–14 nonbuoyant sclerotia per liter. Viability of buoyant sclerotia in samples taken from below 0.6 cm was between 13 and 35%. In the same zone, viability of nonbuoyant sclerotia was between 12.5 and 22.6%. Nonbuoyant sclerotia became buoyant after drying for 48 hr but lost buoyancy after less than 48 hr in water.