果树生产上经常有成龄树改劣换优的做法。某果园将5～8年生树,从地面10厘米处锯掉,上面劈接1～2个枝;或在分蘖处芽接1～2个芽。另有一果园,同样改劣换优,只在主枝头上枝接,但对原来的枝不加管理,结果主枝头生长衰弱,分蘖枝旺长,原品种长势不均衡,嫁接枝生长不良。 Fruit trees are often poor quality of aging trees change practice. An orchard will be 5 to 8 years old trees, sawing from the ground 10 cm above the split 1 to 2 branches; or sprouting at the tiller 1-2 buds. Another orchard, the same change of mercy, only in the main branches of the branches, but the original branches unmanaged, the main branch of the results of weak growth, tillering Wang Long, the original varieties of uneven growth, poor growth of grafted branches .