Recently Westar Energy began a program to treat trees in the path of utilities with Shortstop, a Tree Growth Regulator. Some of the objectives of the program are: 1) To slow re-growth after a tree has been pruned and thereby lengthen the interval in which that tree will need to be pruned again; 2) To reduce the amount of pruning waste when that tree does need to be pruned again; 3) To improve the overall health and appearance of the tree.
So, how does Shortstop help Westar Energy achieve these goals? The active ingredient in Shortstop, paclobutrazol, has widespread use in the greenhouse and ornamental production industries to produce more compact plants using fewer pruning, shearing, or pinching events. The compound works by inhibiting the production of a class of plant hormones called gibberellins. One of the primary roles of the gibberellins is cell elongation. Plants treated with paclobutrazol have a similar number of leaves and internodes, but the internode length is greatly reduced. The result is a more compact plant. Paclobutrazol also increase chlorophyll content yielding a ‘greener’ plant, and research has shown it may increase stress tolerance in trees by increasing fine root densities.
When utility arborists come through your neighborhood to prune branches away from the power lines, you may receive a door hanger indicating that the tree will soon be treated with a plant growth regulator. The product, Shortstop, is applied to the soil at the base of the tree. It is fairly immobile in the soil, so it will not travel and influence the growth of other plants. The result should be a darker green tree with a more compact habit and potentially improved drought tolerance. Due to the reduced growth rate, the time period before that tree will need to be pruned again is extended, and the amount of pruning debris is reduced when it finally is time to prune again.
While there are many benefits to treating street trees with Shortstop, you can say ‘No thank you,’ and your trees will not be treated. For more information visit the ReliabiliTree site (www.westarenergy.com/reliabilitree-program). (Jason Griffin)