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(一)问题的提出近几年来,各地广泛栽培香椿,栽植量年年大幅度增长。但是,香椿发病死亡,是比较普遍严重的。1969年夏,我们开始察觉到这个问题,并在附近三个公社的立地条件各不相同的三个大队栽植的香椿中,选取典型,对它的发病率、死亡率作了调查统计,并对它的发病原因、条件作了分析研究,同时进行了综合防治试验。下表是发病率的统计:
(I) Proposal of the Question In recent years, Toona sinensis has been widely cultivated in various places and its planting volume has risen substantially every year. However, the incidence of toon death, is more common and serious. In the summer of 1969, we began to perceive this issue and selected among the toon-planted Toona sinensis planted by the three brigades with varying site conditions in the three communes nearby. The incidence and mortality rates were investigated and statistically analyzed. Its etiology, conditions were analyzed, at the same time a comprehensive prevention and control test. The following table is the incidence of statistics: