By Laura Pottorff, Colorado State University Cooperative Extension agent and Certified Plant Pathologist
Look at your ponderosa pine trees. What do you see?
If you see needles, at the end of branches, turning brown, join the club.Your pine tree is bearing witness to the dry winter.
Austrian pine appear to have been spared, but Colorado's ponderosa trees need moisture year round to keep their needles "a perfect green."
Here's what happened to the ponderosas: With the lack of significant moisture for several months in a row, and with temperatures in the 40's and 50's, they (and other evergreens) became metabolically active. As a result, the needles begin to respire and lose moisture. With no soil moisture available to replace that which was lost, dehydration occurred. Brown needles and tips are the result.
The solution? Water once a month during dry fall and winter periods. Obviously it's too late for that now, so what should you do? Unfortunately nothing much can be done at this point. The damage is already done. New buds on most of these trees are green and succulent-- a very good sign. New growth will occur if the buds are green. In the longer term, the trees should be fine. The brown needles, however, will remain. DO NOT remove branches that are displaying brown needles. If you do, you risk removing the new buds and any potential for new growth.
Why didn't Austrian pine show the same damage as ponderosa pine? Because Austrian pine adapts better to urban soils. Ponderosa pine do not do as well in the heavy clay soils found in urban areas. Many experts feel that ponderosa pine should be left in the foothills and mountains where they are native. Austrian pine is the preferred pine for urban areas.
Photograph courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010