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1987年秋季泰安市郊区的一个梨园,暴发了一种前所未见的梨果实病害。8月下旬始见少数梨果罹病,9月上旬黄梨品种的病果率达到20%以上。此病症状,先是在果面上出现水浸状小点,2—4天后扩展成直径1—2cm的褐色病斑,同时向果肉深部发展。病部果肉腐烂变软,有臭味,手触之即下陷。病果稍摇晃便落地,落地后多失去梨形。不同品种发病轻重(病果率)大不相同,黄梨最重,鸭梨较轻,晚三吉梨和苹果梨未见有病果。分离病果得到的是一种细菌。经平板划线纯化,得到的优势菌株,在27℃下肉汁胨琼脂平板培养4天
A pear garden on the outskirts of Tai’an in the autumn of 1987 broke out an unprecedented pear fruit disease. In late August saw a small number of pear fruit disease, yellow pear varieties in early September disease rate reached 20% or more. Symptoms of this disease, first appear in the fruit surface flooding dot, 2-4 days after the expansion into the diameter of 1-2cm brown spots, while deep development of the pulp. Sick flesh decay soften, stink, hand touch that is subsidence. Sickly shaking the disease and then landing, lost more pear-shaped landing. The incidence of different species severity (disease rate) vary greatly, the most heavy yellow pear, pear lighter, late Ji-Ji pear and apple pear no disease. The result of separation is a kind of bacteria. The dominant strain obtained was streaked and purified by agar plates for 4 days at 27 C