辽宁地区柞树早烘病发病规律研究

Study on Prevalence of Disease of Oak′ Abnormally Withered Disease in liaoning Province

通过对辽宁省西丰县、沈阳市及凤城市的几个发病较重柞蚕场的调查和查阅相关资料,研究发现柞树早烘病开始发生于8月下旬,大面积的早烘病开始于9月上旬,此病首先发生在柞树下部枝条的基部叶片上,再向中上部叶片发展。发病初期在柞叶边缘处出现褐色的小斑点,分布不均匀,以后斑点继续扩大,由叶缘部位不均匀地向中部扩展,最终叶片全部变成褐色,但叶片并不脱落。一般柞墩密度大、根刈树形、北向坡(阴坡)、坡度大的蚕场早烘病发病重;从树种看辽东栎、蒙古栎发病较重,槲和麻栎较轻;从树的枝龄来看,3￣5年生或者更老枝龄的柞树发病严重,1￣2年生的枝龄不发病或发病较轻。

Based on the research of several oak fields with higher incidence of the abnormally withered disease, such as Xifeng, Shenyang and fengeheng, the disease was studied. The results showed that the abnormally withered disease of oak started in late August and extended greatly in early September. The disease first appeared in leaves of lower branches, then in the middle part of a oak. At initial stage, small brown spots appeared in parts of leaf fringe and extended to the whole leaf fringe in succession. With the extending of spots, the whole leaf became brown and did not fell off in a few days. There were serious diseases in following conditions of tussah field： great stump density, no-stem tree type, seldom sunshine, great gradient. There was a serious disease in Quercus mongolica Fisch, Q. liaotungensis Kvidz, a light disease in Q. dentate Thunb, Q. acutissima Carr. According to ages of branches, there were serious diseases in more than 3 ages of branches, light diseases in one or two ages of branches.