Preliminary Examination of Blast Thresholds for Seed Borne Rice Blast in Arkansas

Rice blast, caused by the fungus, Magnaporthe grisea, is a common disease of rice in Arkansas. The disease has reached epidemic levels previously in Arkansas on susceptible cultivars. Also, it has been established that artificially infected seeds placed on the soil surface could initiate disease in small plots. The research reported here was conducted in small plots to determine if naturally infected seeds planted beneath the soil surface were capable of producing significant levels of rice blast disease. In addition, experiments were conducted to determine if seed treatment with fungicides reduced or eliminated the presence of M. grisea on seeds. The results of field tests appeared to indicate that planting naturally infected seed subsurface leads to significant levels of rice blast disease in the cultivars tested. Preliminary investigations also suggest that fungicides can reduce the presence of blast on seeds.