【摘要】 <正> 目前在栽植杨树新区,食叶害虫十分严重。据调查,杨扇舟蛾、杨尺蠖、杨毒蛾和杨梢叶(虫甲)等食叶害虫,近来经常猖獗成灾,对杨树生长造成了重大损失。为避免任意使用农药,消除害虫产生抗药性和环境污染,我们研究了杨树摘叶量、杨扇舟蛾食叶量与生长关系,找出食叶害虫虫口密度与食叶量多寡与树木生长关系,提出合理的防治指标,为实现综合防治提供依据。更多还原

【Abstract】 Based on the effect of natural defoliation of pest insects on thegrowth of poplar tree,an artificial defoliation has been made to observethe influence of this treatment on poplar tree’s growth.The resultsobtained are as follows: 1. There was no significant effect of artificial defoliation 25％ and50％ on the growth in diameter and in height,as compared with thecontrol.However,a defoliation of 75％ and 100％ resulted in thedecrease of 21.2％ and 50.8％ in diameter and 20.5％ and 44.7％ in heightof the tree tested,respectively. 2. The average amount of leaves eaten by a single Clostera anachoreta(Faby.) from the first generation to the fourth generation was 15935mn~2,8184mm~2,10226mm~2,14168mm~2,respectively.更多还原