Kelly Jackson
Christian County Extension Office
Topping Trees Bad Practice
The practice of topping damages hundreds of trees each year in Kentucky. Trees are subjected to many stresses during their lifetime (i.e., insects, diseases, lightning strikes). Topping is one form of stress that can be avoided. Unfortunately, it remains a common practice because many people are unaware of its detrimental effects to trees.
Topping is the drastic removal, or cutting, of large branches in mature trees which leaves behind a leafless stub. This practice is frequently the result of trying to manage trees incorrectly planted near overhead utilities or too close to structures. Site selection must always be considered before planting in order to provide any tree with sufficient room to grow.
Removing too much of a tree’s canopy upsets the crown-to-root ratio causing serious interruption of the tree's food supply. For example, a 20-year-old tree has developed 20 years worth of leaf surface area. This leaf surface is needed to manufacture sufficient food to feed and support 20 years worth of branches, trunks and roots. Topping not only cuts off a major portion of the tree's food-making potential, it also severely depletes the tree's stored reserves. Removing a large portion of the tree's canopy also exposes bark to the sun's direct rays, often scalding the suddenly exposed outer bark. Severe sun scald will cause the bark to split thereby obstructing the flow of nutrients.
Large branch wounds left from topping seldom seal or callus. Without callus tissue, the wounds become vulnerable to insect invasion and fungal decay. Once decay has begun in a branch stub, it may spread to the main trunk, ultimately killing the tree.
Some homeowners believe that new growth stimulated by topping is actually beneficial to the tree. Although new foliage and branches make the tree appear rejuvenated, damage has occurred. Topping removes existing buds that would ordinarily produce normal strong sturdy branches. Instead the re-growth of dense, upright branches, or watersprouts, is stimulated just below the pruning cut. Watersprouts that form near the pruning cut are not well integrated into the wood of the tree, weakly attached, and thus vulnerable to breakage caused by wind and ice. As watersprouts fall, they create a new potentially hazardous situation that can only be remedied by either tree removal or the continual practice of tree topping. Since watersprout re-growth is generally rapid and vigorous, a topped tree often will grow back to its original height faster and denser than a tree that has been properly pruned or thinned. Also note that some tree species such as sugar maple, oak and beech do not readily produce watersprouts. Without the resulting foliage, a bare trunk results and the tree quickly dies.
Topping removes dead or diseased branches and healthy branches alike. In some situations, removal of a large healthy limb may be necessary; however, correct pruning alternatives such as proper early training, selective thinning of branches and limbs, or whole tree removal should be alternatively considered and adopted.
Finally, from an aesthetic aspect, topping disfigures trees. Unsightly branch stubs, conspicuous pruning cuts, and broom-like branch growth replace the natural beauty and form of a healthy tree.
Topping is, at best, only a temporary solution to an oversized tree. Financially speaking, proper pruning work may cost more initially but a continual topping scenario can be more costly over the lifespan of the tree or its owner. Since topping most often occurs to trees under utility lines or that have grown too large near homes, here is a list of trees for small spaces, under 25 feet tall: Trident Maple, Flame Maple, small Japanese Maple cultivars, Tatarian Maple, Autumn Brilliance Serviceberry, Fringe Tree, Kousa Dogwood, Winter King Hawthorn, Amur Maackia, various cultivars of flowering crabapple, Leonard Messel Magnolia, Star Magnolia, Snow Fountains Cherry, Snow Goose Cherry, Weeping Yoshino Cherry, Ivory Silk Tree Lilac, and various weeping tree varieties.