【摘要】 1960—61连续二年在河北衡水施用颗粒剂防治玉米螟:春、夏玉米心叶末期用5% DDT 颗粒剂,不仅前期的螟虫减少了80—90%左右,穗期的螟害也适当地被控制。1次施药能减少整个春玉米生育期的虫数65—77.4%,夏玉米60—71.9%。防治效果似与玉米后期虫口密度有关。心叶期防治以在心叶末期为最理想,提早施药不能获得最高效果。心叶期防治2次与防治1次的效果没有差异。心叶末期与穗期各防治1次,收获时检查,防治效果春玉米上可达85.8—88.6%,夏玉米90.6—91%。因此,在螟害较轻的年分,防治1次即能解决大部分的螟害问题,大发生年分,可以在穗期再防治1次。试验证明不同载体、不同加工方法配制的颗粒剂、不同用量和不同施用方法的防治效果差异都不显著。虽然含5% DDT 或0.5—1%666的颗粒剂的残效能维持1个月以上,但由于田间植株上残存的颗粒剂损失很快,1个月后的残存量仅为12—15%,因此1次防治的效果受到限制。由于防治效果与施药时螟卵发生的情况关系不大,而心叶未期是防治最适时期,因此作者建议可以玉米生育阶段作为施药时期的标准。更多还原

【Abstract】 Field plot tests on the control of the European corn borer,Pyrausta nubilalis Hubn.,withgranulated insecticides were carried out at Heng-shui,Ho-pei,during the year 1960-1961.One application of 5% DDT granules at the late whorl stage reduced the earlier borerpopulation about 80-90%,and the insecticides deposited in the leaf axils remained sufficientlyeffective for the control of those larvae hatched after tasselling.The total borer populationbrought under control by a single application was 65-77.4% on corn planted in the spring and60-71.9% on corn planted in the summer.The best time for a single treatment was found tobe late whorl stage,earlier application of granules would be less effective.Double applicationsof insecticides,with the first at the late whorl stage and the second at the silking stage,weremore effective.The borer population on corn planted in spring and summer was reduced85.8-88.6% and 90.6-91:0%,respectively.No significant difference was found between formulations,dosages,and methods of applica-tion.Although the residual toxicity of 5% DDT and 0.5-1.0% γ BHC granules was found tobe well above one month,as the insecticides deposited in the leaf axils lost 85-88% of theiroriginal quantity within the same period,it is concluded that double application might benecessary espeeially when borer population is high.As the relation between amount of egg laying and the effectiveness of insectieidai applica-tion was insignificant,it is suggested that growth stage of corn can be used as the basis fortiming the insecticidal application.更多还原