Abstract
The sheath pathogen complex, comprising Rhizoctonia solani, R. oryzae, R. oryzae-sativae, and Sclerotium hydrophilum, causes a significant loss of rice yield in Asia. This study was carried out to characterize the causal agents of rice sheath diseases in Myanmar and to study the relationship among different isolates of R.solani from Myanmar, Japan, and Vietnam. Diseased rice stems, including those with unidentified symptoms in the field, were collected from different rice growing areas. The number of isolates of R. solani, R. oryzae, R. oryzae-sativae, and S. hydrophilum was 89, 110, 137, and 25, respectively. Genetic characterization of Rhizoctonia spp. was performed using the repetitive element PCR assay. R. solani AG-1 IA, R.oryzae, and R. oryzae-sativae collected from Myanmar were classified into two, two, and three different population types, respectively. The isolates of R. solani from Myanmar, Japan, and Vietnam were characterized into four distinguishable groups (RS1-4). RS1 isolates were a Myanmar-specific group, while the other groups were found in all of the tested regions.
