水稻条纹叶枯病的为害损失及防治指标

2004-2006年在浙江北部系统地调查了水稻条纹叶枯病发病动态和为害损失。单季晚稻秧田期介体灰飞虱有效虫量（X2）与水稻株发病率（Y1）的关系式为Y1=0.0873 + 1.0757X2，晚稻本田株发病率（X）与产量损失率（Y）总关系式为Y=0.1254+0.7551X。在现有生产条件下，经济允许水平以损失率表示为2.0%~2.5%，制订了水稻条纹叶枯病防治指标为水稻秧苗期和本田前期介体灰飞虱有效虫量2~3头/m2，该指标已在生产上大面积推广应用。

Rice Yield Loss Caused by Rice Stripe Disease and Economic Threshold

Rice stripe disease,transmitted by the rice small brown planthopperLaodelphax striatellus Fallén(Homoptera: Delphacidae),has been a severe devastating disease in Northern Zhejiang,China since 2004.To understand the relation of rice grain yield loss to the incidence of the disease and the density of the vector,a series of experiments were conducted from 2004 to 2006 in rice fields.The results showed that the incidence of the disease(Y1) at the seedling stage increased with the increasing density of infectious vector(X2) as the equation of Y1=0.0873 + 1.0757X2,while the rice yield loss(Y,%) increased positively in a linear mode with the incidence(X,%) in the single-cropping late rice asY=0.1254 + 0.7551X.The economic injury level(EIL) was calculated as 2.0%-2.5% of yield loss according to the current economic scenarios for rice production for the control of the disease.Therefore the economic threshold for controlling the disease was set as the density of 2-3 per square meter of the small brown planthopper in the seedling nursery and at the early stage in rice fields.Such economic threshold has been practically applied in control of the disease in large scale fields and a significant economic benefit has been achieved.