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松苗猝倒病是我省松杉类树种苗木上最普遍和最严重的病害,是松杉育苗工作中最大的障碍。根据历年来各地的调查,幼苗被害率一般达30—60％,个别严重地区发病率高达70—90％,甚至全部毁灭。如1971年江宁县陶吴公社等地,所育杉苗重者死亡率达90％。猝倒病除为害柏类以外的各种针叶树,还为害桑树、刺槐、海棠、臭椿、银杏、榆、枫杨、枫香、石楠、紫荆等阔叶树种,以及瓜菜和各种农作物,为害范围极其广泛。 一、松苗猝倒病症状类型 1.种芽腐烂型:种子未发芽前即可受害,使种子腐烂,或种子胚芽刚外露时受害,使胚芽腐烂,直至胚芽达2—3厘米长,并伸出地面后还可受害而腐烂。 2.猝倒型:苗木揭草后即可看到,先在茎基部发生水渍状病班,后缢缩而倒伏;
Pine seedling damping off disease is the most common and the most serious diseases of coniferous fir tree seedlings in our province, and it is the biggest obstacle in the work of growing fir seedlings. According to surveys all over the years, the rate of seedling damage is generally 30-60%, and the incidence in some serious areas is as high as 70-90%, or even totally destroyed. For example, in 1971, Jiangning County, Tao Wu commune and other places, the mortality of seeding fir seedlings reached 90%. In addition to cataplexy poisoning all kinds of conifers other than cypress, but also for mulberry, acacia, begonia, Ailanthus, ginkgo, Ulmus, Maple, sweetgum, heather, Bauhinia and other broadleaf species, as well as vegetables and various crops, the scope of the damage Extremely wide range. First, the seedling damping-off symptoms of a type of seed rot type: the seed can not damage before germination, the seed decay, or germination of the seed germs just exposed, the germ decay until the germ reaches 2-3 cm long, and stretch After the ground can also suffer and decay. 2. Cataplexy type: seedlings can be seen after being uncovered, first in the base of the water-based stain disease class, after shrinking and lodging;