美国植物检疫条例中规定禁止从特定国家进口植物或植物体的某个部分,这是因为在这些国家中有对美国有检疫重要性的病虫害发生。这些病虫害的大部分,诸如潜隐性的病毒或潜伏的锈菌,用常规的方法在检验进口材料时不能检定出来。当进口其寄主植物时,在美国的进口港的检验与处理无法保证防止这些病虫害的进入。因而颂布法规拒 The United States Phytosanitary Regulations prohibit the importation of plant or plant parts from a particular country because of pests and diseases that are of quarantine importance to the United States in these countries. Most of these pests, such as latent viruses or latent rusts, can not be detected by routine methods when testing imported materials. When importing their host plants, the inspection and handling of the import ports in the United States can not guarantee the entry of these pests and diseases. So Chung cloth laws refused