Ecological control of seedborne rice diseases using processed rice seed (Gennmai seed)

Mechanization of rice cultivation has developed very rapidly, and transplanting machines have been adopted all over Japan. Rice seedlings grow very close together in the nursery boxes and under high humidity the close intra-row spacing. This method of cultivation creates favorable conditions for seedborne diseases. All the diseases, except sheath blight, are seedborne and cannot be controlled completely with seed disinfectants. For that reason, pathogen-free seeds (Gennmai seeds) have had the chaff removed so that fungal and bacterial pathogens cannot survive in the tissues of the seeds. The surfaces of hulled rice with healthy embryos have also been coated with a water-soluble polyacrylic resin and a powdery activated carbon. This study reveals that the Gennmai-seeds prohibit to a remarkable degree the development of seedborne diseases such as rice blast, bakanae disease, bacterial grain rot, and bacterial seedling blight. Pathogen-free seeds (Gennmai seeds) can effectively contribute to the eradication of seedborne diseases.