随着市场经济的发展，农产品在市场上的流通和交换频繁，使许多随农产品传播的害虫和病菌，到处传播蔓延。农业种植结构调整和种植技术的不断提高，再加上近年来华北地区夏、秋季节持续高温干旱、冬春温暖多雨的气候特点，以及不合理的化学防治和日趋严重的环境污染，使玉米、 With the development of market economy, the circulation and exchange of agricultural products in the market are frequent, causing many pests and germs spread with agricultural products to spread everywhere. Agricultural planting structure adjustment and planting technology continues to improve, coupled with the summer and autumn in North China sustained high temperature and drought, winter and spring warm and rainy climate characteristics, and unreasonable chemical control and increasingly serious environmental pollution, so that corn,