Signs from the Pines
Within the past 30 to 45 days, many Colorado spruce and pines have taken on a poor crown appearance. What we see unfolding in the evergreen trees now could be a prelude to the 2011 growing season. Since the Mountain Pine Beetle has made a significant presence in pine trees on Colorado’s Front Range, it is not business as usual for pine trees in Denver and other urban Colorado areas.
Pines are Storytellers
Dendrochronology is the discipline of correlating tree growth rings with significant historical events. Analysis performed on both live and preserved fossilized trees have identified volcanoes, fires and climatic events. Spruce and pines can also identify specific events, especially over the past five years. Three to five years of retained foliage act as a living report card of tree vitality. Robust annual twig growth (elongation) and normal needle length and color are indicators of a good year. Short annual growth and off-color, stunted needles indicate poor growing conditions. Growth years may be compared and contrasted to identify increasing vigor, decreasing vigor, or a recent sudden event.
What’s Happening Now
Since August 2010, the prevailing climate has been unseasonably warm and dry. In the last 30 days, most of Colorado’s Front Range has been categorized as being in a severe drought. In Denver, only 14 inches of snowfall has been recorded this season in contrast to a normal 50 inches. Strong winds have desiccated evergreen foliage. Three basic scenarios exist:
1. Loss in foliage color and browning of needle tips. These changes indicate desiccation damage. In most cases, the new growth will develop normally on these individual branches and the older needles will fall off.
2. Interior needles turning straw color and/or individual branches dying. This is a tree survival technique. By shedding unthrifty needles and branches, sugar and water resources are conserved. The resulting tree canopy will be sparse.
3. Entire tree turns brown. Winter, as well as the new spring growth, is fueled by the previo us year’s energy (sugar) reserves. If the tree runs out of energy to sustain itself, it dies. Trees infested in 2010 with Ips Beetles are also fading at this time.
What To Do
Recommendations are site-specific. If your landscape is populated with evergreen trees, now is the time to contact Swingle to perform a plant health care inspection with recommendations. Swingle has been the preferred Colorado tree care, shrub care and lawn service company since 1947.
Colorado Tree Care: Stories are Your Evergreen Trees Tell