杂草是农业的一大害,其造成的农业损失愈来愈引起了人们的重视。联合国粮农组织近年曾作过估计,全世界每年因草害造成作物减产值高达204亿美元。以美国为例,每年因病、虫、草害造成作物减产值高达120亿美元以上,其中草害居第一位,占42％,虫害占28％,病害占27％,线虫占 Weeds are a major hazard of agriculture, and the agricultural losses caused by it have drawn more and more attention. In recent years, the UN’s Food and Agriculture Organization has estimated that the world’s crop reduction each year caused by grass-weeds up to 20.4 billion US dollars. Take the United States as an example, the crop production value caused by diseases, pests and weeds is up to more than 12 billion U.S. dollars each year. Among them, the grass ranks the first place with 42%, pests 28%, and diseases 27%