论文部分内容阅读
在京郊农业生产中,蔬菜占有重要地位。大白菜是京郊蔬菜的主要品种,每年从■月一直供应到翌年3～4月,约占全年蔬菜总上市量的十分之四。大白菜生产上的主要问题是产量不稳。造成产量不稳的因素很多,其中尤为突出的是:(1)三大病害(孤丁病、霜霉病、软腐病)。特别是孤丁病和霜霉病的流行,经常造成严重减产,同时又不
Vegetables in the suburbs of Beijing occupy an important position in agricultural production. Chinese cabbage is the main variety of vegetables in the suburbs of Beijing. It is supplied from March to April in the following year every year, accounting for about four-tenths of the total annual market volume of vegetables. The main problem in the production of Chinese cabbage is its unstable yield. There are many factors causing instability in production. Among them, the most prominent ones are: (1) Three major diseases (solitary and downy mildew, soft rot). In particular, the prevalence of solitary and downy mildew strains, often resulting in serious cuts, at the same time not