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在病、虫、杂草的化学防除中,农药使用方法的正确与否,不仅与提高工作效率、节省农药有关,更重要的是对防治效果的影响很大。例如在防治棉花红蜘蛛中,使用无内吸作用的三氯杀螨醇,如果药液喷不到叶背或喷药不均匀,这样效果就差;如喷药量过大,又易使作物发生药害。再如,防治小地老虎的方法要考虑它的生活习性,在其三龄前幼虫抗药力很小,可用喷雾或撒粉的方法防治;但到四龄以后,抗药力增强,幼虫白天钻在作物根部附近的土内,到晚上才出来为
In the disease, insects, weeds, chemical control, the correct use of pesticides, not only with improving work efficiency, saving pesticides, more importantly, the effect of prevention and control of a great impact. For example, in the control of cotton spider mites, the use of non-systemic effects of dicofol, if the liquid spray can not spray leaf back or uneven, so the effect is poor; such as the spray amount is too large, but also easy crop injury. For another example, the method to control the small tiger to consider its living habits, before the third instar larvae resistance is very small, can be sprayed or dusted method of prevention and treatment; but after the fourth instar, the resistance increased, the larva drilling in the daytime The soil near the root of the crop came out at night