农药使用效果差的七种原因防冶农作物病虫害，当前仍以喷洒农药为主，但在生产实践中，常出现合格农药却使用效果不理想的情况。究其原因，有以下七点：一、诊断错进。病当虫治，虫当病治。如果树早期落叶，当作红蜘蛛危害；番茄青枯病死苗，错诊为地下害虫咬根等等，这样... Seven reasons for the poor use of pesticides Preventive plant diseases and insect pests, spraying pesticides are still the main, but in production practice, the use of qualified pesticides often appear unsatisfactory. The reason, the following seven points: First, the wrong diagnosis into. Disease when the worm, insect treatment when the disease. If the tree early deciduous, as a red spider harm; tomato wilt dead seedlings, misdiagnosed as underground pests bite, etc., so ...