水稻是日本的主要粮食作物,常年栽培面积占总耕地面积的41～45%。在水稻生产上,1976～1985年十年中,因病虫为害每公顷平均每年所造成的损失,虫害为14公斤,病害为270公斤,稻瘟病为346公斤。病害为害损失重于虫害,病害中发生为害最重的是稻瘟病,一般发病年损失稻谷20万吨,重发病年损失超过50万吨。流行因素及其特点稻瘟病在日本全国各地均有发生,过去每隔数年流行一次,70年代后期以来,由于品种 Rice is Japan’s major food crop, with perennial cultivated area accounting for 41-45% of the total cultivated area. In rice production, the average annual loss per hectare caused by pests and diseases in the ten years from 1976 to 1985 was 14 kg for pests, 270 kg for diseases and 346 kg for blast diseases. Disease damage is heavier than pests, disease damage is the most important rice blast, the general incidence of annual loss of 200,000 tons of rice, heavy disease loss of more than 500,000 tons. Epidemic factors and characteristics of rice blast in Japan all over the country have occurred in the past once every once in a while, since the late 70s, due to species