By Mary Small, Colorado State University Cooperative Extension, Urban Integrated Pest Management
Evergreen needles often turn brown or appear to be "burned" during the winter and early-spring months. This is because evergreen needles transpire (lose moisture) on warm, sunny winter days just like they do during the growing season. If the ground is frozen or too cold, the evergreens may not be able to replace the lost moisture or be able to replace it fast enough to keep up with the loss. As leaf-moisture loss continues, needles dehydrate, turn brown and may drop.
At this point, the damage has already occurred. You can prevent further damage by applying water to the tree's absorbing root system. The absorbing roots are located at a distance equal to two to three times the height of the tree, away from the trunk. If the pine was planted during the last two years, concentrate the water in the root-ball area and under the drip line (the outermost extension of the branches). New growth will eventually mask the brown needles. Beginning around Nov. 1 and continuing through March 1, water evergreens monthly in the absence of sufficient rainfall or snowmelt.
When soil temperatures are above 40 degrees, the root can absorb and use the water.
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010