乌鲁木齐地区大白菜花叶病流行主要因素的初步分析

在烏魯木齐地区,有翅甘藍蚜的迁飞高峯期与大白菜幼苗花叶病的发生密切有关。如迁飞高峯期在极易感病的大白菜幼苗初期(7月下旬),則病害发生普遍而严重;若迁飞高峯期推迟到8月中旬,則病情显著減輕。 1960至1963年研究观察結果指出,烏魯木齐地区6月份及8月上旬的降雨量,对有翅甘藍蚜在整个生长季节中的发生量、迁飞量与迁飞高峯期,有直接的影响,是决定本地区大白茶花叶病大区流行程度的主要因素。甘藍面积的扩大、毒源与蚜源距离的縮短、甘藍的零散栽种,职及种植甘藍的年数增多等情况,是促使大白菜花叶病小区流行程度更趋严重的因素。在病情特重的烏魯木齐地区,采用大白菜晚播措施,不能达到減輕病害的目的。

SOME FACTORS INFLUENCING THE EPIPHYTOTICS OF MOSAIC DISEASE OF CHINESE CABBAGE IN URUMCH, SINKIANG

In Urumch, Sinkiang, epiphytotics of Chinese cabbage mosaic appéared to be determined chiefly by the time of occurrence of the flight peak of cabbage aphid alatae, which occurred during late July in 1960-1962, years of severe epiphytotics, and mid-August in 1963, a year of moderate epiphytotics. It was found that the heavy rainfalls in June and August in 1963 kept down the aphid population and checked the activity of the alatae. In Urumch the acreage, distribution, field proximity, and number of years of continuous cropping of cabbage, the source-crops of the virus and the aphid were the factors found to be closely correlated with the prevalence of the Chinese cabbage mosaic. Experimental results obtained in different localities showed that late planting usually decreased the incidence of the disease in light, but not in heavy epiphytotic areas.