Rhizoctonia solani Kühn is a devastating soil-borne pathogen that can infect a wide range of crops, including sugar beet. It was estimated that 24% of sugar beet planted in US and 5-10% in Europe can be affected by this fungus. The fungal pathogen has been classified into thirteen main anastomosis groups (AGs). In Minnesota and North Dakota, AG 2-2 (IIIB and IV), which cause root and crown rot, is the most important for sugar beet production. In addition, AG 4 has been found to cause the seedling damping-off in sugar beet. Other AGs and sub-groups are also present at low frequency in US. Overall, the signs, symptoms, morphology and infection process of different AGs on sugar beet are not very clearly defined. Therefore, this study is to examine morphological, genetic and virulence diversity of R. solani in sugar beet. A total of 400 isolates of R. solani has been collected from sugar beet fields across US. Initial microscopic observations indicated conspicuous variation in colony morphology. The future work includes characterization of those isolate using microsatellite and genotyping-by-sequencing approaches (GBS). Primers have developed based on the draft genome of AG 2-2 IIIB available in the gene bank. GBS data would reveal the genomic complexity among the AGs. Furthermore, this research would provide knowledge and tools for a sustainable management of this important pathogen in sugar beet.