There are several things you should avoid when pruning a tree. You don't want to do more harm than good.
Bad Pruning Methods
Topping and tipping are pruning practices that harm trees and should not be used. Crown reduction pruning is the preferred method to reduce the size or height of the crown of a tree, but is rarely needed and should be used infrequently.
TIP: Our expert gardening advisor, Susan Patterson adds, "Never top a newly planted tree."
Figure 1 Figure 2
Topping, the pruning of large upright branches between nodes, is sometimes done to reduce the height of a tree (Fig. 1). Tipping is a practice of cutting lateral branches between nodes (Fig. 2) to reduce crown width.
These practices invariably result in the development of epicormic sprouts, or in the death of the cut branch back to the next lateral branch below. These epicormic sprouts are weakly attached to the stem and eventually will be supported by a decaying branch.
Bad Pruning Cuts
Improper pruning cuts cause unnecessary injury and bark ripping (Fig. 3). Flush cuts injure stem tissues and can result in decay (Fig. 4). Stub cuts delay wound closure and can provide entry to canker fungi that kill the cambium, delaying or preventing woundwood formation (Fig. 5).
| Figure 3. Bark ripping
|| Figure 4. Flush cutting
|| Figure 5. Stub cutting
Courtesy of the US Dept. of Agriculture.