上强下弱树是有中干的王林、红富士等苹果树经常遇到的现象。 造成这种现象的原因是:①中央主干连年长留,壮枝、壮芽带头,未实现折叠或弯曲延伸,上长过快。②主枝角度过小,树冠抱合,或对第一层主枝剪得过 Weak under the strong tree is dry in the Wang Lin, Fuji and other apple trees often encounter the phenomenon. The reasons for this phenomenon are: ① even the central trunk stay older, Zhuang Zhi, Zhuang Ya take the lead, did not achieve the fold or bend extension, too fast. ② The main branch angle is too small, crowns, or cut to the first layer of main branches too