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Making Room at the Top

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Published on: Apr. 2, 2000

Last revision: Nov. 4, 2010

The number of cuts made on each tree tends to be fewer and the remaining branches are growing away from wires. Time between needed prunings tends to be greater. This all adds up to time saved for pruning crews and fewer electrical outages. Property owners and the general public benefit from safer, healthier, nicer looking trees along streets and roadways. This, not heading or topping, is the pruning technique people should emulate.

Natural target pruning doesn't solve all problems with trees growing under utility wires. Some trees may appear lopsided or bisected, or they may be left with gaping holes, even when correct pruning cuts are made. These shortcomings may be especially obvious when a utility company changes from old heading methods to natural directional pruning, or with trees that require removal of large limbs low in the tree.

Some trees will suffer extreme treatment regardless of the pruning approach, simply because they are the wrong tree in the wrong place. Many utility companies will remove problem trees under wires if it proves the best overall solution. Some companies even offer to replace problem trees with new ones that will not interfere with wires.

Natural target pruning or directional pruning is now practiced by many Missouri utility companies--some have used these methods for years. Five utility companies in Missouri have been recognized by the National Arbor Day Foundation as Tree Line USAs for using approved pruning practices, providing regular training for their crews and promoting well managed municipal trees. These companies are City Utilities of Springfield, the Light & Power Company of St. Joseph and the Water and Light Department of Columbia, Ameren UE of St. Louis and Independence Power and Light. In fact, Missouri is now the national leader in companies so honored.

DO YOUR PART

Utility companies continue to make progress in the quality of their line clearance work, but there are also things we all can do to improve the condition of trees along streets, in parks or in our yards.

  • Plant the right tree in the right place. Don't plant tall-growing deciduous species such as oaks, maples, ashes, sycamore, pines or spruces beneath utility wires. Lower-growing trees, such as redbuds or crabapples, may be appropriate for planting under wires, but check with your utility company or city government if planting on the street right-of-way to be sure.
  • Observe pruning work done in your area for utility wire clearance. Know that some pruning cuts must be made to provide needed clearance that would not be needed for other trees. Support efforts of your utility company to prune trees using natural target pruning principles.
  • Consider removing trees under utility wires if they must be harshly pruned to provide clearance or are in poor condition.
  • Encourage tree workers in your community to use natural target pruning and other good tree care methods for all trees. Employ a trained arborist or commercial tree care service for trimming work. Don't top trees.

If you would like more information about managing or planting trees near wires, or about the Tree Line USA program, contact the Urban Forestry Coordinator, Missouri Department of Conservation, P.O. Box 180, Jefferson City, MO 65102.

Pruning Methods Contrasted

Heading Method

  • Branches are shortened, leaving stubbed-off branch ends.
  • Sprouting occurs near the ends of cut branches. Branches grow back, only thicker.
  • Regrowth is weakly attached and breaks easily in storms
  • Can cause dead branch stubs. Maximizes chances for future decay inside branches and trunk.
  • Trees require pruning as soon as regrowth enters area needed for clearance.
  • Especially destructive if applied to entire tree.
  • Produces a whole population of weak, unhealthy trees over time.

Natural Directional Pruning

  • Whole branches growing toward conductors are removed, leaving branch collars intact.
  • Only offending branches are removed. Remaining growth is directed away from wires
  • Future storm damage is minimized
  • Tree can grow over pruning wounds. Chances for decay are minimized.
  • Tends to lengthen time needed between prunings.
  • Works with natural growth habit of tree.
  • Encourages trees to grow safe and sound.

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