冻害是我国柑桔栽培北缘地区的主要灾害,公元1111—1949年,长江中下游地区发生过江湖结冰60次,因寒冷天气使柑桔树几乎冻死有19次,解放后,也发生过3次冻害。据中央气象局提供的资料,上述地区的极端最低气温达-7—-12℃,其多年平均值为-5—-10℃,因而柑桔树经常受冻。在这个地区中出现中度冻害的机率,普通甜橙为30％左右,宽皮柑桔南部为10％左右,北部达20％左右。 Frost damage is the main disaster in the northern margin of citrus cultivation in our country. During the period from 1111 to 1949, there were 60 rivers and lakes frozen in the middle and lower reaches of the Yangtze River. Citrus trees were almost frozen to death for 19 times due to the cold weather. After the liberation, 3 times cold damage. According to the data provided by the Central Meteorological Bureau, the extreme minimum temperature in these areas is between -7 and 12 degrees Celsius, and its average annual temperature is between -5 and 10 degrees Celsius. Citrus trees are often subject to freezing. In this region there is a moderate risk of frost damage, the average sweet orange is about 30%, the width of the citrus is about 10% in the south, up to about 20% in the north.