小麦条锈病与吸浆虫混合危害损失估计

Loss Assessmant of Stripe Rust Together with Wheat Midge

1992～1994年研究了小麦条锈病与吸浆虫共同危害对小麦产量的影响。当小麦吸浆虫和条锈病同时发生时，随着病、虫数量的增加，稳重的减少与每稳虫量呈曲线相关，而与条锈病的病情指数呈线性相关。不同年份间病害与虫害的损失当量基本一致；当病、虫的数量相同时，干旱年份作物的实际损失比正常年份大。正常年份小麦条锈病的病指（x）和每穗吸浆虫数量（z）造成的产量损失（L％）模型为：L％=0．0259＋0．0024x＋0．14991g（x）；干旱年份的损失模型为；L％=0.111＋0．002372＋0．14701g（x）。病虫混发时的防治指标与吸浆虫数量、病害严重度、小麦产量及防治代价等因素有关。

The yield loss of wheat induced by stripe rust and whcat midge had been studied from 1992to 1994. There is a linear correlation between the car wcight of wheat and wheat midges' numbers whilethe wheat midges' numbers on each ear less than 20. The regress slope of loss cquation of ear weight issimilar between different years, but the regress intercept is dissimilar by main reason of the differentrainfall in years. Two models for relative yield loss of wheat were built as a function of stripe rust density(X) and wheat midge' S number(Z).In the normal years it is L% = 0. 0259+ 0. 0024X+ 0. 1499log Z, in the drought years it is L% =0. 11+0.00277X+0. 1470logZ.The threshold of loss is a complicated problem according to wheat midges' numbers, disease density,wheat yield and control cost et al. This paper showed a Dynamic Threshold table in different cases.