桑橙瘿蚊危害后的桑园结构变化及相应管理

桑瘿蚊危害后桑园结构发生了很大变化。桑树受害止芯后，继而生出若干侧枝呈帚状。桑叶密集于条高１．１—１．６米之间，通风透光性变差。叶面积系数可暂时增大。超过未受害区２０％以上。随之下部叶黄化脱落加快，收获叶量减少。五龄用叶期嫩叶比例增大，影响了叶质。受害后采取加强肥水管理，疏芽疏枝，增养夏蚕，继续查虫治虫，严防８月中旬第二次受害等措施，可以减少和避免损失。

STRUCTURE CHANGE AND ADEQUATE CONTROL OF MULBERRY FIELD HARMED BY MULBERRYGALL MIDGE(Diplosis mori Yokoyama)

Great changes took place in the structure of mulberry field damaged by mulberrygall-midge.After terminal bud of the harmed mulberry stopped growing,the plant pro-duced many lateral branches in the shape of broom.The length of branch was between1.1 1.6 metres,the leaf distribution was dense.This led to poor ventilation and illumi-nation.The leaf area index seemed to grow large for a spell.It could be 20%higher thanthat of the unharmed mulberry field.Consequently,leaves of the lower portion grew yel-low and fell off earlier,leaf yield decreased.Besides,too many tender leaves were therewhile the larvae were at the 5th stage.The loss could be decreased or avoided by adopt-ing adequate measures such as:Strengthening mannuring and irrigation; Thinning budand branch; Rearing silkworm in summer to make good use of the lower leaves in time;Go on eliminating harmful insects to prevent mulberry from being damaged again afterthe middle of August.