马尾松毛虫防治指标的研究

<正>1983～1985年,在江苏省溧水林场对马尾松毛虫室内外取食针叶量、自然虫害和人工剪叶模拟虫害以及各种防治方法的效益等进行了测定和调查。结果表明,松毛虫自然为害与人工剪叶模拟处理对树木生长量的影响是趋于一致的。稂据松树损失针叶量与树木生长损失量的关系,提出了该地区马尾松毛虫的防治指标。

A STUDY ON THE CONTROL THRESHOLD OF DENDROLIMUS PUNCTATUS WALKER

In order to determine when and whether or not controlling D. punctatus with chemical, the effects of artificial defoliation and the caterpillar larvae have been studied. The results are as follows:There is no significant effect between artificial and natural defoliation for the volume growth rate. If the tree is defoliated to 70% or more, there is significant as compared with those non-defoliated. And if the tree is defoliated nearly 100% duririg the August or September, nearly 25 percent of trees died and the percentage of volume is lowering to 31% of the normal. In general,the trees injured heavily (?)y the pest recover at third year.The control threshold tables are developed as following empirical formula:CT = A(1293.4D + 4684.5C-626.2H-4088.5)/14.20where, CT = the larvae density that can be controlled with the chemicals, D = the diameted breast high (cm.) of the tree; H = the height (m.) of the tree;C = the ratio of the crown length/height of the tree; A = the degree of the defoliated from 10%to 90% ; 14.20 = a constant destruction by a single larva.