Climbing spurs are tools that arborists use to climb trees they are removing. They are not intended for use when pruning a live tree. Use of climbing spurs, also called gaffs, climbers, or spikes, can damage a live tree in a number of ways.
Climbing spurs needlessly create holes in trees. These holes damage some of the vital tissue of the tree, called cambium. The wounds may encourage the growth of unwanted shoots, called water sprouts. In addition, the holes allow a sight of entry for wood decay organisms. It is also possible for infected climbing spikes to transfer some disease organisms from diseased trees to healthy trees, much the same way the common cold can be spread from person-to-person.
In addition to health concerns for the trees, the holes that climbing spikes leave are just plain unsightly and can diminish the dollar value of your trees!
This information is not new even though some tree workers continue to use climbing spurs to climb trees when pruning. In fact, it has been known for well over 100 years that climbing spurs should not be used when pruning a tree.
The improper use of climbing spurs led A. Des Cars, author of Tree Pruning, to write the following quote in 1881, "Except in very exceptional cases, or where very large trees are to be operated on, the climbing spurs sometimes used by professional pruners should not be allowed. These men, paid according to the number of trees operated on or the quantity of wood cut, have no idea in pruning beyond cutting the largest amount of wood in the shortest time. Climbing spurs should never be used by good workmen. Wounds made by the sharp iron teeth of this tool encourage the growth of injurious side shoots on the trunks, and leave defects in the wood which never disappear and diminish its value." - excerpted from Sierra Moreno Mercantile Company catalog, 1986.
Here are some tips to use when hiring an arborist to prune a tree: Ask what equipment they plan to use when climbing your tree; Ask if they prune according to the American National Standards Institute (ANSI) A300 Tree Pruning specifications; Ask them to write pruning specs according to ANSI A300; Always get more than one quote and ask for references.