Rice blast, caused by Magnaporthe oryzae is one of the most devastating diseases affecting rice production in the Asia-Monsoon region, with estimated global yield losses ranging from 10% to 30%. Introducing resistant varieties is a promising strategy to simultaneously decrease environmental impact and improve sustainable productivity. However, the breakdown of resistance owing to pathogen evolution is a recurring issue. In the context of sustainable rice production in the Asia-Monsoon region, establishing an international collaboration system that enables the consistent evaluation of blast pathogen virulence across the region is essential, as it facilitates the identification of resistance traits in rice genetic resources, and tracks regional pathogen dynamics.

This report introduces the concept of differential system for blast resistance and international deployment of a blast differential system via collaborative research between JIRCAS and IRRI. Subsequently, this report presents case studies of applying the Differential System in Vietnam and Bangladesh under the Green Asia Project, aligned with Japan’s “Strategy for Sustainable Food Systems, MIDORI.” The case studies include the analysis of long-term monitoring data on the dynamics of rice blast pathogen virulence in Vietnam, field assessment of the resistance of introgression lines in Vietnam, and validation of pesticide reduction using introgression lines with partial resistance genes in field trials conducted in Bangladesh.

These results indicate that the effectiveness of resistance genes significantly differs by location and time, highlighting the criticality of continuous surveillance and strategic gene combinations, whereas introgression lines introducing resistance genes (Pb1 and pi21) showed broader and more durable resistance compared to the original variety and the potential for pesticide reduction without considerable yield loss via resistant variety adoption.

These results support key policy goals such as decreasing environmental burdens, enhancing disease management efficiency, and optimizing pesticide use. Accelerating technology dissemination through farmer demonstrations and strengthening breeding strategies and pathogen monitoring systems are necessary for the development of sustainable blast management.

This report provides practical insights into rice blast management and contributes to the realization of sustainable rice production in the Asia-Monsoon region.