我区自五十年代初引种苹果以来,发现“冻旱”(2—3月)危害幼树越冬,造成“抽条”死亡。以后,又相继发现早霜冻(即深秋冻,9月底—10月上旬)、仲冬冻(11月中旬)、深冬冻(12月—1月)和晚霜冻(即春霜冻,4月下旬—5月中旬)等多种类型的冻害。特别是近年在1981年出现的严重早霜冻害,使成批的幼令苹果园和 Since the introduction of apples in our district in the early 1950s, it has been found that “freezing drought” (February-March) harms young trees to winters, resulting in the death of “splinters”. Later, one after another found that the early frost (that is, deep autumnal freezing, late September - early October), midwinter freezing (mid November), deep frozen winter (December-January) and night frost (ie spring frost, Mid-May) and many other types of frost damage. In particular, the severe early frost damage that occurred in recent years in 1981 made batches of young apples and orchards