近几年小麦白粉病危害逐年加重.小麦受白粉病危害后,对产量究竟有多大影响,国外曾对此作过研究.据美国约翰逊报导,种感病品种Chancellor比抗病品种产量少收34%.Large和Doling(1963)报导,产量损失率=2 x~(1/2)(x为发病率).由于产量损失除与病指高低和病害发生早晚有关外,同时也受环境与品种的影响,因此,这些数据是否适合我国情况,需进一步验证.为此我们进行了三年研究,第一年采用田间选穗法测产,误差很大,以后则按国内外对农作物叶部病害为害损失研究法进行,从而获得了一个中病指与一个低病指的两个回归方程,具有较高精确度和可靠性.现将进行情况分述于后. In recent years, the harm of wheat powdery mildew has increased year by year.Wheat wheat powdery mildew endangered by the impact on yield exactly how much has been studied abroad.According to Johnson, USA, the susceptible variety Chancellor yield less than the yield of 34 % .Large and Doling (1963) reported that the yield loss rate = 2 x ~ (1/2) (x is the incidence rate) .In addition to yield loss in addition to the level of the disease and the disease occurs sooner or later, but also by the environment and species Therefore, whether these data are suitable for our country need to be verified further.To this end, we conducted a three-year study, the first year using the field election ear test method, the error is very large, then according to the domestic and foreign crop leaf disease Loss of damage research method, which obtained a pathogenic index and a low disease index of the two regression equations, with high accuracy and reliability, the situation will be described later.