By Steve Boehme
Large, mature trees often interfere with utility lines, block important views, grow too close to buildings or crowd neighboring trees. Very often trees are planted without considering their final mature size, and this can lead to many problems including the cost of “topping” as the trees grow.
Topping, also referred to as heading, stubbing, trimming or dehorning, is the drastic removal or cutting back of large branches in mature trees, leaving large stubs. This practice was once thought to be a good way to reduce the height of trees considered too large for a particular site.
Utility companies frequently top trees to protect overhead wires. However, a topped tree often will re-grow to its original height faster and with greater density than a tree that has received proper pruning.
Topping injures trees in many ways. Removing a major portion of the canopy upsets the delicate balance between foliage and the rest of the tree. Tree leaves manufacture chemical energy required by the tree for growth and maintenance of branches, trunk and roots. A tree’s energy-producing potential is severely reduced when large portions of leaf surface area removed. Large reserves of stored energy in many stems and branches also are lost when trees are topped.
Large branch stubs that result from topping invite insects and wood-rotting pathogens, which find the living but defenseless stub an inviting and plentiful source of food. Stubs can’t wall-off or heal over the wound or protect themselves. Once decay has entered the branch stub, it progresses into the main trunk, hollowing out and eventually killing the tree.
Topped trees grow vigorous “water sprouts” just below the pruning wound. These rapidly growing shoots have very weak attachment to the remaining stub, making them vulnerable to wind and ice damage. Sprouts resulting from topping are very succulent and more susceptible to attack from insects and diseases, particularly fire blight.
Bark suddenly exposed to the sun after topping often is damaged by sunscald, and may become diseased, further weakening the tree.
Because the results often are short-lived, topping actually is a more costly solution to the problem of interfering trees than selective thinning or pruning. Topping disfigures the tree and ruins its beauty, replacing its natural form with unsightly branch stubs, ugly pruning wounds and a “witch’s broom” of branch re-growth.
There’s a slippery slope of expense involved once a tree is topped for the first time, a step which costs hundreds of dollars. It’s just a matter of time until the tree re-grows, this time with weakly attached water sprouts, and will need topping again. Eventually the whole tree will have to be removed.
The real solution to this problem is to select trees that fit the space. There are trees available that will grow to every shape and size imaginable, from dwarf ornamentals to huge towering shade trees, from narrow columnar forms to wide spreading canopies. The first step in selecting which tree to plant is to figure out how tall and wide it can get before outgrowing the space where you’re planning to plant it.
Steve Boehme is the owner of GoodSeed Nursery & Landscape, located on Old State Route 32 three miles west of Peebles. To e-mail your landscaping questions click “Contact Us” from their website at www.goodseedfarm.com or call (937) 587-7021.