Improper Pruning


Figure 1, Photo by Bruce Hagen

This method of managing trees is called ‘topping’ or heading back and is used to describe a fairly common, yet sub-standard pruning method to reduce tree height and spread. Topping destroys natural shape, weakens structure, reduces health, and useful life span. Typically, all of the branches are shortened and much of the foliage is removed. In this manner, trees are disfigured, and greatly devalued. Topping also stimulates sprouting near where the cuts are made. These sprouts are fast-growing, crowded and prone to breakage as they increase in size. Furthermore, branch stubs often decay, increasing the potential for limb failure.

Topping also starves trees by removing too much of the tree’s leafy crown and dangerously reduces the tree’s food-making ability. Topping can kill older or stressed trees.

Removing all the tree’s foliage-cover exposes its bark tissue to direct sun which can result in sunburn damage to the previously shaded bark, exposing the wounded tissue to colonization by wood decay fungi or wood-boring insects.


Figure 2, Photo by Bruce Hagen

Another example of topped trees.


Figure 3, Photo by Bruce Hagen

Business owners are often concerned that people in cars can see their business. They respond by pruning them harshly. It's important to recognize that it's the tree's foliage that provides all the benefits. The point of planting and maintaining trees is to provide and maximize shade. Moderate pruning often becomes necessary to maintain safety, maintain adequate clearances, or improve aesthetics. Pruning like this reduces the amount of shaded parking that customers covet, and adversely affects tree health and longevity.

In this case, many of the lower and smaller interior limbs were removed creating ‘lion-tailing’. Lower and smaller interior laterals make the main trunk or scaffold structure more stable by helping to dissipate the wind-loading or prevent it from whipping around in the wind. This type of pruning also increases the risk of limb failure. Lion’s- tailing weakens branch structure, increases limb breakage potential, stimulates water sprouts and can lead to sunburn injury. Of greater concern, though, is that this practice leaves few options to shorten over-extended branches or reduce end-weight in the future. In many cases, thinning outer canopy foliage, installing a supplement support system or removing large branches are the only options left to reduce the potential for limb failure.


Figure 4, Photo by Bruce Hagen

In this case, all of the branches with foliage were cut off, which stimulated the production of vigorous, but weekly attached shoots. Sprouting from the bark rather than growth from the buds it the tree's 'fail-safe' system to prevent death. A tree's leaves are essential to make sugar, a source of energy used to maintain all of its living cells. All of the energy that trees and plants need come solely from the sun through photosynthesis. The roots provide only water and minerals.