在果树生产中，经常会发生各种自然灾害，特别是早春晚霜冻的危害，致使果树发育受到抑制或局部花芽冻死、花期冻花、个别年份苹果树落花后遇低温，幼果受冻，果实萼部周围出现环状伤疤，造成幼果大量脱落，严重时落果率高达30％～50％以上，损失严重。一、早春晚霜冻危害果树 In the production of fruit trees, all kinds of natural disasters often occur, especially the frost damage of early spring and early evening, causing the development of fruit trees to be inhibited or local flower buds freezing and freezing, flower blossoming. In some years, Ring appearing around the calyx fruit scars, causing a large number of young fruit off, severe decapitation rate as high as 30% to 50% or more, the loss of serious. First, early spring night frost damage fruit trees