Establishment of an Experimental Method for Evaluating Rice Sheath Blight Resistance

Rice sheath blight, caused by Rhizoctonia oryzae, is one of the most destructive diseases affecting rice during the critical growth period in August, leading to significant yield losses. With the increasing frequency of sheath blight outbreaks under climate change, the identification of resistant rice germplasm has become an essential priority for breeding programs. In this study, approximately 150 long-grain rice accessions were screened to establish an effective method for evaluating sheath blight resistance. At the 4–6 leaf stage, rice seedlings were inoculated at the basal sheath with 14-day-old R. oryzae cultures and incubated under controlled conditions (31 °C, 100% relative humidity). Lesions first appeared 4 days after inoculation, and by day 10, typical symptoms extended to the upper sheath region at 15–20 cm. These results provide a reliable experimental framework for assessing resistance to rice sheath blight and offer a foundation for the selection of resistant germplasm in future breeding and disease management programs. [This work was supported by the Rural Development Administration of Korea (RS-2025-02214096)]