病虫预测预报,通常是通过取样调查来估计病、虫在田间的密度、发育进度(流行速度)及对作物为害程度等.而这,必须事先明了一定虫期或病害发生期病虫在田间的分布情况,并根据这种分布特点来选定适宜的调查取样方法. Prediction of pests and diseases is usually based on sample surveys to estimate the disease, the density of insects in the field, the progress of development (prevalence) and the degree of harm to the crop, etc. However, it must be clear in advance that pest or disease at the stage of pest or disease occurs in the field According to the distribution of characteristics to select the appropriate survey sampling method.