冀南棉麦混作区棉花害虫综合防治技术的研究

1983—1985年在河北南部棉麦混作棉区设点,进行了以棉蚜、棉铃虫为主要对象的综合防治技术研究。从棉田生态系的整体出发,根据棉花、害虫与天敌各主要组成成份的特点及相互关系,尽可能利用自然因素,设计了以棉麦邻作布局、种子处理、棉田内分阶段衔接种植诱集植物油菜——春玉米——夏玉米来保护增殖自然天敌、制订合理防治指标、减少用药和加强棉田栽培管理、种植抗病品种等配套技术的农业防治、生物防治和化学防治相结合的综合防治措施,经3年来多点大田试验、示范、应用,结果表明在控制虫害、减少用药、保护增殖天敌、降低防治成本等方面效益明显。

STUDIES ON THE INTEGRATED CONTROL OF COTTON INSECTS IN NORTH CHINA

This work was carried out in 1983-1985 at Handan,Hobei province, where the main crops are cotton and winter wheat and the key pests of cotton are the cotton aphid, Aphis gossypii Glover and the cotton bollworm, Heliothis armigera(Hübner). The current control work for these pests relies almost solely on the use of insecticides.This project aimed.(1) to develop control measures other than chemical control, especially those based on more sufficient utilization of natural factors such as the varietal resistance to insects and diseases, various agrotechanical measures and the natural enemies of pests;(2) to establish an approprate economic threshold for chemical control and (3) to design an effective, economic and enviromentally safe in tegrated control system.The current chemical control of the cotton bollworm emphasizes both the second and the third generations, especially the second brood. Because it was believed that during the second generation, bollworm injury is the chief cause of falling squares. The authors proved that the occurrence of the second brood bollworm synchronizes with the squaring stage of cotton, during this period the compensating ability of cotton plants is very high. Hence, the control index for the 2nd-generation ought to be higher than that for the 3rd-brood. According to field experiments, the economic thresholds for the second and third generations were revised to be 20 early instar larvae/100 plants and 6 early instar larvae/100 plants respectively.A new integrated control system has been designed as follows:(1) seed treatment with carbofuran;(2) improving cultural practices to promote the compensating ability of cotton plants;(3) on the basis of the local cropping system of cultivating wheat and cotton in adjacent fields, where the wheat fields serving as sources of natural enemies of insect pests, intercropping serially with adequate crops in cotton fields to facilitate the immigration and favourable development of insect predators and parasites;(4) adopting the revised economic thresholds for ascertaining necessary applications of insecticides and(5) using disease resistant cotton varieties. Field experiments and actual control work in large scale of this integrated system proved that the populations of natural enemies were obviously raised, insect damage avoided and the number of insecticide applications might be reduced by 3-4 sprays annually. Therefore, this system is proved to be effective, more economic and may reduce enviromental contamination.