油菜死苗是我区油菜生产上一个急待解决的问题。根据我所近几年试验,造成油菜大面积死苗的原因主要是烂根、露根和弱根,其中尤以烂根较为普遍和严重。一、烂根:油菜烂根多是由于播种过早而引起的。有的人错误地认为,粗大菜根就是壮根,只有早播才能形成壮根。实践证明,过早播种的油菜冬前早旺,吸引大量根蛆为害,致使油菜烂根严重。同时,过早播种的油菜,冬前生长时间过长,越冬菜根虽然粗大,但菜根的糖分和含水量不高,结果不是壮根越冬而是老根越冬,冬前和春后常有菜 Rape seedlings is the rapeseed production in our area an urgent problem to be solved. According to my tests in recent years, resulting in large areas of rapeseed dead seedlings are mainly root rot, root and weak roots, especially rotten roots are more common and serious. First, rotten roots: Rape rotten roots are caused due to premature planting. Some people mistakenly believe that the root is the strong root vegetables, only the early sowing to form strong roots. Practice has proved that premature sowing of premature rapeseed Wang, attracting a large number of root maggot damage, resulting in rotten roots rape. At the same time, premature sowing of rape, winter growth time is too long, although the overwintering Caiotou coarse, but the root of sugar and water content is not high, the result is not strong root winter wintering roots but old, often before winter and spring vegetables