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背景和现状 江苏棉区从五十年代开始应用农药防治棉花害虫取得了显著成效。南通棉区每亩棉田用25％二二三乳剂1.5—2.0斤和有机磷50—100毫升,投资费约为2.0—2.5元,治虫增产效果可达15％左右,每1元农药投资的增产值约5—6元。然而,进入六十年代以后,一些害虫已出现了抗药性,致使农药用量和防治次数不断增加。到七十年代每亩棉田农药用量增加到25％二二三乳剂2.5—3.0斤和有机磷250—500毫升,农药费5—6元,治虫
Background and Current Situation Jiangsu Province has achieved remarkable results in the application of pesticides to control cotton pests since the 1950s. Nantong cotton area with 25% per acre cotton two hundred twenty-three emulsion 1.5-2.0 kg and 50-100 ml of organic phosphorus, the investment cost of about 2.0-2.5 yuan, the effect of pest control increased by about 15% per 1 yuan increase in investment in pesticides Output value of about 5-6 yuan. However, since the 1960s, some pests have become resistant to pesticides, leading to an increase in the amount and control of pesticides. By the 1970s, the amount of pesticides per mu of cotton fields increased to 25%. The amount of pesticides used in the second and third milks of milk was 2.5-3.0 kg and organic phosphorus was 250-500 ml. The pesticide cost was 5-6 yuan.