棉花苗期棉蚜防治指标的研究

棉蚜(Anhis gossypii Glover)是上海郊区棉花早中期主要害虫之一,但近几年来,很多人改变了对棉蚜为害的看法,有的认为有虫无害,有的认为天敌能控制棉蚜为害,所以可以不进行防治。作者从1977～1981年对棉蚜的为害进行了研究,为综合防治提供正确的防治指标。本试验在小区及大田中进行。结果表明,在1～2张真叶卷叶时,单株减产率为31.02％～51.46％,而在3～4张真叶时为24.80％～42.97％,在大田条件下,不同卷叶株率(x)与减产率(Y)的关系式为: y=0.7034×-1.4641利用y=0.7034×-1.4641关系式,结合当地棉花的生产水平,可确定防治指标。

STUDIES ON THE CRITERIA FOR CONTROL OF COTTON APHIS APHIS GOSSYPll GLOVER IN THE SEEDLING STAGE OF COTTON

In Shanghai,cotton aphis is one of the important pests of cotton at its eariy and middle growth stage.But in recent years,concept regarding the damage caused by cotton aphis has been changed.Some do not consider cotton aphis as a harmful pest,and others think that natural enemy is capable of controlling the cotton aphis,therefore,control measures are not necessary.The damage caused by cotton aphis was studied during 1977~1981,and adequate control criteria have been suggested for comprehensive control. This experiment was conducted in field plots as well as in the field.The result obtained shows that the yield decrease for individual plant of 1~2 leaf stage was 31.02~51.46%,while that of the 3~4 leaves stage was 24.80~42.97%.Under field condition the percentage of curlyleaf plant (x) and the percentage of yield decreased(y) can be expressed as a linear regression equation,y=0.7034x-1.4641. Using this regression equation and at the same time consulting the cloal productive level of the cotton crop,the control criteria can be worked out.