2. Evolution of guiding principle of plant protection In the early 1970’s, Chinese experts in plant protection brought in a guiding principle in plant protection work based on a summarization of experiences since new China built, This guiding principle is “ putting prevention first and integrated control ” The connotation of this guiding principle is to take overall situation of agricultural production as a starting point in consideration, flexible, safe, economized and effective control measures should be taken according to the relationship between pests and host crops. The goal of plant protection is to increase yield of crops and income in agriculture. In practice, however, the meaning of “control” was once taken as “ kill all pests. ”
