今年我区鄂晚5号为主的稻瘟病严重发生,造成严重减产,其中以穗瘟减产最重。现将其发生特点及原因浅析如下: 1 发病特点 1.1 苗瘟、叶瘟、穗瘟连发 今年我区晚稻的苗瘟病苗率一般在20％～30％,重病田超过50％;叶瘟发生早,新老病叶共存时间长,而且随着晚稻分蘖的不断增加,新病叶不断产生,尤其是急性病斑的数量大(单叶病叶最多达23个),持续时间长,导致发病面积不断扩大,病情不断加重,孕穗后期重病田上三叶急性病斑的病叶率达34.7％,抽穗期上三叶叶枕瘟率达32.6％～44.7％;今年穗瘟虽然早在9月下旬就发病,但病害大量表现和加重期在10月上中 This year, my area Obo late on the 5th of the main occurrence of rice blast seriously, resulting in serious cuts, of which the earliest cut ear blast production. Now its characteristics and causes are as follows: 1 Morphological characteristics 1.1 Seedling blast, leaf blast, panicle blast bursts of hair This year, my area late rice seedling blast rate is generally 20% to 30%, severe disease more than 50%; leaf blast Occurring early and new old leaves co-exist for a long time, and with the continuous increase of tillering of late rice, new leaves continue to produce, especially the large number of acute lesions (single leaf diseased leaves up to 23) for a long time, resulting in Disease area continues to expand, the condition continues to worsen, severe disease in the late bout of acute disease three leaves on the sick leaves rate of 34.7%, heading stage cotyledons pillow disease rate of 32.6% ~ 44.7%; Although this year as early as September In late onset, but a large number of disease performance and aggravating period in October on