进行轮作和间作是防治病虫害和提高产量的措施之一。据苏美等国的究研表明,棉花黄萎病、枯萎病之所以流行,在很大程度上与棉花连作有关。在进行棉花连作的棉田中,由于棉杆翻入土中,使土壤中病菌逐年增多,造成病害蔓延减产。而棉花与苜缩轮作,可降低黄萎病、枯萎病的危害。以近年来黄萎病、枯萎病盛行的苏联乌兹别克棉区为例,连作棉田占该区棉花总播种面积的92.8％,而采用棉花、苜蓿轮作的仅占3.5％。美国在棉盲椿象和棉铃虫危害严 Rotation and intercropping are one of the measures to prevent pests and increase production. According to studies by countries such as the Soviet Union and the United States, the reason for the prevalence of Verticillium wilt and blight in cotton is largely related to the continuous production of cotton. In the continuous crop of cotton fields, cotton stalks turned into the soil, so that the soil bacteria increased year by year, resulting in reduced disease spread. The cotton and alfalfa round, can reduce the risk of Verticillium wilt, blight. Taking the Uzbekistan cotton area in the Soviet Union where verticillium wilt disease and wilt disease prevail in recent years as an example, continuous cropping cotton fields account for 92.8% of the total sown area of ​​cotton in this area, while cotton and alfalfa rotations account for only 3.5%. The United States is badly endangered by cotton blight and cotton bollworm