1冻害症状核桃树受冻害较轻时,秋梢抽干,多发生在1~2年生树及当年嫁接后生长的新梢。冻害严重时,主干产生纵向裂纹,部分主枝及多年生大枝死亡。1~3年生树根颈部形成层受冻后,先产生环状褐色坏死斑,以后皮层变褐腐烂,流出黑水,严重时整株死亡。根系冻害表现在春季萌芽晚或不整齐,或在放叶后出现干缩等现象,刨出根系可发现皮层变褐、皮层与木质部 1 Freezing damage symptoms Walnut trees suffer less damage when frozen, autumn tip drained, occurred in 1 to 2 years old tree and then grow new shoots after grafting. Serious freeze damage, the trunk longitudinal cracks, some of the main branch and perennial big branch died. 1 to 3-year-old tree roots neck layer of frozen, the first ring-shaped brown necrotic spots, after the cortex brown rot, out of black water, severe death of the entire plant. Root frostbite in late spring budding or irregular, or after the leaves appear shrinkage and other phenomena, planing the roots can be found brown cortex, the cortex and the xylem