Seedling blight of rice is the main factor that decides the success or failure of a nursery. The pathogen that cause seedling blight are complex. The pathogen are mostly soilborn, and they may be different depending on different locale. To resolve this problem, we used a commercially available non-pesticide chemical, namely, phosphorous acid, and included two microorganisms of Trichoderma spp. and Bacillus mycoides ,and mixed it (this mixture is called "3-in-1"). We applied it to seedlings during the early stages of greening to induce immunity. Moreover, the microorganisms within help to protect roots. This has a double effect of resisting disease and promoting growth. Results show that by treating our 3-in-1 formula, disease index of seedlings blight was 0.25%, seedling height of 13.12 cm, and the weight of roots per standardized unit of volume (39.74 cm3) was 2.42 g. In contral, seedlings treated with pesticides had a disease index of 6.88%, seedling height of 9.01 cm, and a root weight per standardized unit of volume of 1.13 g. Untreated seedlings had a disease index of 47.35%, seedling height of 8.94 cm, and a root weight per standardized unit of volume of 0.94 g. It is thus apparent that our 3-in-1 formula produces much better results than pesticides or untreated. Furthermore, observation in the fields showed that the disease of rice blast and sheath blight were also decreased.