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大白菜霜霉病是白菜三大病害之一。1972年以来,我市多次流行,影响白菜产量。我们通过研究,开展综合防治,取得了成效,近两年,全市大白菜平均单产稳定在4,246—5,560斤。一、摸索流行规律,进行预测预报,重点防治。我们着重分析气候与大流行的关系:(1)8月份低温来得早是病重的预兆。发病重的1972年,最低温度20℃以下到来的时间是8月22日,1974年是8月23日,而且持续9天低温有雨。1971、1973年这种气候9月才发生。8月份低温有雨,有利于病原菌孢子囊的萌发侵入,引起苗期发病,增加当年病菌基数。(2)9、10月的温湿度是发病的条件。病害大流行年份,
Cabbage downy mildew cabbage is one of the three major diseases. Since 1972, the city has repeatedly prevailed, affecting cabbage production. Through research, we conducted comprehensive prevention and treatment and achieved fruitful results. In the recent two years, the average yield of Chinese cabbage in the city has been stable at 4,246-5,560 kg. First, to explore the prevailing laws, forecasting and prevention, focusing on prevention and treatment. We focus on analyzing the relationship between climate and the pandemic: (1) It is a sign of serious illness in August when it comes to low temperatures. Severe onset in 1972, the minimum temperature below 20 ℃ arrival time is August 22, 1974 is August 23, but continued for 9 days low temperature and rain. 1971, 1973 This climate did not happen in September. Low temperature and rain in August is conducive to the germination of pathogen sporangia invade, causing disease at seedling stage, increasing the number of germs in the current year. (2) September and October temperature and humidity are the conditions of onset. Disease pandemic year,