美国由于长期种植多种小麦品种，结果使部分抗白粉病的品种变得不抗病了。在美国中西部，白粉病在小麦叶片上能形成条纹，在湿润的东南部更普遍。据统计，美国每年因白粉病危害损失达650、2000万美元。用农药防治花费更大。最近，美国科学家用从伊朗和美国采集的野生小麦进行抗 Due to the long-term cultivation of a variety of wheat varieties in the United States, some powdery mildew-resistant varieties have become non-resistant. In the Midwestern USA, powdery mildew is stripe-forming on wheat leaves and more prevalent in the wet south-east. According to statistics, the U.S. damages each year by powdery mildew amounted to 6.52 billion U.S. dollars. Pesticide control costs more. Recently, U.S. scientists used wild wheat collected from Iran and the United States for resistance