８０年代以来，三麦产量不高不稳，原因很多，杂草的严重危害是其中一个重要制约因素。尤其是日本看麦娘、猪殃殃、大巢菜等草种所组成的群落危害更为突出。据１９８７～１９８８年调查，日本看麦娘和看麦娘之比由８０年代初的１：９上升为９：１，平均每平方米达４６７２株。 Since the 1980s, three wheat production is not high and unstable, for many reasons, the serious damage weeds is one of the major constraints. Especially in Japan to see Maiang, Galium aparine, nest grass and other grass communities formed by the more prominent harm. According to a survey conducted in 1987-1988, the ratio of Japan’s Amanita and Amanita increased from 1: 9 in the early 1980s to 9: 1, with an average of 4672 plants per square meter.