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棉铃虫Helicoverpaarmigera（Hubner）是棉花整个生育期的主要害虫，近几年来，越来越严重地影响棉花的产量和品质，为及时准确地做出发生期预报，指导防治，减轻其为害，笔者根据本站1982～1994年间年系统调查资料，运用加机频率法[1]对2代棉铃虫发生期预报进行了研究。1材料
Helicoverpa armigera (Helicoverpa armigera) (Hubner) is the main pest of cotton throughout the growing period, in recent years, more and more seriously affect the yield and quality of cotton in order to make timely and accurate prediction of the occurrence, guidance and prevention and mitigation of damage, the author based Based on the annual systematic survey data from 1982 to 1994, the forecast of the occurrence of the second generation cotton bollworm was studied by using the method of adding frequency [1]. 1 material