日本稻瘟病发病情况在日本,由稻梨孢(稻瘟病菌)引起的稻瘟病在病害中最为严重,尽管受害面积和发病率随栽培期气候条件因年而异。然而,如(图1,略)所示,自1976年以来,除了1980年叶瘟和穗颈瘟病情严重及1984年叶瘟大面积发生外,受害面积的总趋势是在减少。日本稻瘟病的发生和病情发展过程已基本清楚。在最低气温高于16℃以及当日和次日有雨时,水稻田会初次受到稻瘟病菌的侵染。正常年份中,日本北部水稻田叶瘟病斑一般在六月底七月初首次出现,那些地区大多在五月底前插秧,插秧后至初次发生叶瘟一般相 The incidence of rice blast in Japan The rice blast caused by rice borer (Pyricularia oryzae) is the most serious in Japan, although the area and incidence of the damage vary with year due to the climatic conditions during the cultivation period. However, as shown in Figure 1, the general trend of the affected area has been declining since 1976, except for the severe cases of leaf-blast and pan-neck blast in 1980 and the large-scale outbreak of leaf-blast in 1984. The occurrence and progression of rice blast in Japan are basically clear. Rice fields were first infected with Magnaporthe grisea at a minimum temperature above 16 ° C and on the same day and next day. In normal years, the leaf blast patches in paddy fields of northern Japan first appeared in late June and early July, most of them were transplanted before the end of May, and the initial phase of leaf blast occurred after transplanting