Technical Abstract: Rice sheath blight, caused by the fungal pathogen Rhizoctonia solani (AG1-IA), is an economically important disease in Arkansas. To identify the sheath blight resistance gene(s) an extensive molecular and pathological characterization of R., solani was initiated. A wide range of pathogen isolates was collected from rice fields in Arkansas. DNA primers from unique regions within the ribosomal DNA (rDNA) internal transcribed spacer (ITS) of R. solani have been used for the sequence analysis of the representative isolates. Preliminary analysis suggests that a group of fast growing pathogen isolates emerged in the Arkansas rice fields.