*Rhizoctonia solani* is a devastating pathogen causing sheath blight in rice. This study developed a colorimetric LAMP assay for its rapid detection. Four primers targeting the polygalacturonase (PG) gene showed specific amplification, with q-PCR detecting up to 10 pg of DNA. A colorimetric LAMP assay, coupled with a rapid template preparation method, visually confirmed the pathogen within 45 minutes. The LAMP assay's sensitivity was 1.65 fg/µl, effectively detecting *R. solani* AG-1 IA from diseased tissues and soil. High specificity was demonstrated by the lack of amplification with other AG groups and related fungi/bacteria. This assay offers a point-of-care diagnostic tool for early monitoring and preventive measures.
