Abstract

EVANS, P. and J. E. KLETT. 1985. Pruning at planting may not enhance growth. Am. Nurseryman 1 62(8):53-57, 60-61.

A rule of thumb in the nursery business is that 30 percent of the tops of bare-root trees should be removed at planting time. Since a tree’s fibrous root system is reduced to a few woody stubs during digging, it seems appropriate to reduce the top in some proportion before replanting. However, for almost 100 years, good evidence has existed that dormant pruning may not be beneficial for all bare-root trees. The Department of Horticulture at Colorado State University, Fort Collins, has studied branch thinning with two species that are commonly planted bare-root (Newport plum and Sargent crabapple). One of the surprising results of these experiments was that the variability in new root production was high. Regardless of pruning treatment, the difference in new root development between trees within each group was large enough that no effect of top pruning on root production could be found. Most top pruning on these species might profitably be delayed until the second or third year when more growth is produced. Except for removing major structural defects (such as twin leaders) or balancing the length of major branches, this research indicates that first-year pruning appears largely ineffective in determining structural development or total growth.

• © 1986, International Society of Arboriculture. All rights reserved.