Pathogenicity and symptom expressions of Rhizoctonia solani, R. oryzae and R. oryzae-sativae to some commercial cultivars of rice in Myanmar

Rhizoctonia complex of rice has been detected in rice growing areas of Myanmar. The primary objective of this study is to study the varietal response of rice to Rhizoctonia complex and to distinguish the symptom expression of rice responses to these pathogens. Myanmar rice cultivars namely Manawthukha, Shwethweyin, Sinthwelatt and Yezinlonthwe were used to inoculate with three isolates of each species of Rhizoctonia solani, Rhizoctonia oryzae and Rhizoctonia oryzae-sativae. The symptoms created by each species of Rhizoctonia were distinguished by the size and colour of the lesion. Variation in lesion length was observed among different isolate-rice cultivar combination. Shwethweyin variety is the most susceptible one to all the tested three species among the four tested varieties.