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我们曾于1975年在商县基点进行了玉米大斑病田间发生动态的观察,结果整理如下。一、定点系统观察:选择春、夏播玉米田各一块,每块田顺序固定20株,自发病初开始,每5天调查一次。按叶片九级标准(即严重率以病斑占叶片面积百分率表示,依次为:0,1％,5％,10％,20％,30％,50％,70％,100％),逐株、逐叶顺序记载发病程度,至玉米收获前。 1.发病时期:3月中旬播种的春玉米,5月下旬发病。6月4日(玉米10叶期)第一次调查,严重率1％的病叶6片,5％的
In 1975, we conducted a dynamic observation of the occurrence of maize leaf spot in the Shangxian County base. The results were summarized as follows. First, the fixed-point system observation: Select the spring and summer sowing corn fields, each field order of 20 fixed, since the beginning of onset, once every 5 days. According to the standard of leaf level 9 (ie, the rate of serious disease is represented by the percentage of leaf area in percentage of leaves, which is 0,1%, 5%, 10%, 20%, 30%, 50%, 70% and 100% respectively) , The order of incidence by leaf records, to corn before harvest. 1. The onset period: spring maize sown in mid-March, onset in late May. June 4 (corn 10 leaf stage) the first survey, the serious rate of 1% of the diseased leaves 6, 5%