杂草,它不但妨碍农作物的生长、发育,降低产量和品贸;还能助长病、虫害的发生和蔓延。有些杂草本身合有毒质,牲畜和人类误食以后,会发生中毒现象。有些杂草本身带有强烈的气味,例如乳牛食后,使乳汁有气味,影响质量。所以,国家根据植物的检疫法令,把有害杂草和有毒杂草列为植物检疫对象。 杂草主要是由种子传播的。一株杂草所产生的种子数量是惊人的;而且,有的杂草种子寿命很长,经历多年,仍能存活。有些杂草种子和作物种子大小很相似,不容易分离,常混夹在农作物种子 Weeds, which not only hinder the growth of crops, development, reduce production and trade; but also contribute to the occurrence of disease and pest and spread. Some weeds are poisoned by themselves, poisoned by livestock and human beings. Some of the weeds themselves have a strong odor, such as dairy cattle, the milk smell, affecting the quality. Therefore, the state according to the plant quarantine law, the harmful weeds and toxic weeds as a phytosanitary target. Weeds are mainly spread by seeds. The number of seeds produced by a single weed is staggering; moreover, some weed seeds have a long lifespan and can survive for many years. Some weed seeds and crop seeds are very similar in size and are not easily separated, often mixed with crop seeds