使用化学农药防治农作物病虫害是当前采取的主要措施。但喷药效果往往受到环境条件的影响,为提高药效、降低成本,既要掌握虫情,把握时机,又要考虑气象条件,科学用药,才能达到预期目的。降雨能稀释农药,降低药效,冲掉的药剂还会污染河流、泥塘、水渠,因此施药要选晴天,切忌雨天喷洒农药。乐果、杀虫双等内吸性乳剂。喷洒几小时就能渗透到作物体内,若喷后一昼夜遇雨,对药效影响较小。敌敌畏筹触杀剂、胃毒剂,接触虫体或等待取食,需政长的时间,要使药效显著,喷后须保持两天以上的晴朗天气。另外,空气湿度大,易加速某些农药的分解,产生药害。温度对药效有较大的影响,高温天气药剂的活 The use of chemical pesticides to control pests and diseases of crops is currently the main measure taken. However, the spraying effect is often affected by the environmental conditions. In order to improve efficacy and reduce costs, it is necessary to grasp the pests, seize the opportunity, and take into account the meteorological conditions and scientific medication to achieve the expected purpose. Rain can dilute pesticides, reduce efficacy, washed away chemicals will pollute the rivers, mud ponds, drains, so spraying should be sunny, avoid spraying pesticides on the rainy day. Dimethoate, insecticidal double sucking emulsion. Spray a few hours will be able to penetrate into the body of the crop, if the rain spray after a day and night, less effect on the efficacy. Dichlorvos preparation touch agent, stomach poison, contact with parasites or wait for food, the need for the Chief of the time, to make significant effect, to maintain more than two days after the spray fine weather. In addition, the air humidity, easy to accelerate the decomposition of some pesticides, resulting in injury. Temperature has a greater impact on efficacy, high temperature weather agents live