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Thursday, April 30, 2020

Ponderosa pines, spruce may exhibit ‘winter burn’ by Colorado State Forest Service

A frost-damaged tree. (Courtesy of Colorado State Forest Service)
Ponderosa pines, spruce may exhibit ‘winter burn’ by Colo State Forest Service

A cold snap in October, coupled with last week’s extreme temperature fluctuations, injured ponderosa pines, other pine species and spruce trees in the Douglas and Elbert county areas, including Castle Rock, Franktown, Parker, Elizabeth and Kiowa. With warm weather preceding winter last year, the trees did not have the chance to transition into dormancy before freezing occurred. Large shifts in outside temperatures last week exacerbated the damage.


Blue Spruce with Winter Burn/Jefferson County - Photo: Vicky Spelman
Damaged pine and spruce trees may appear grizzled and possess white or straw-colored foliage, referred to as “winter burn.” Other symptoms may include the tips of needles appearing rust-colored while the base of the needles remains green. While most sightings of pines exhibiting these frost-damage symptoms have occurred in Douglas and Elbert county communities, trees in other areas of Colorado, including the eastern plains, may be experiencing this damage as well.

Unfortunately, little can be done for trees that have sustained winter burn damage, according to Meg Halford, a forester in the Colorado State Forest Service’s Franktown Field Office. However, “the buds on these frost-injured trees may have survived, and they may produce new growth this spring,” Halford said. “Don’t count them out just yet.”
Frost Damaged Tree/Jefferson County - Photo: Vicky Spelman
The CSFS recommends that residents monitor the foliage of their trees for color changes or a brittle appearance. Along with watching for these common frost injuries to their trees, residents should also frequently water their trees to avoid drought-like conditions throughout the spring, summer and fall in the absence of natural moisture from snow and rain. Trees require 10 gallons of water per inch of tree stem (measured 4.5 feet up the tree from the soil) per week during the growing season.

Fall Needle Drop may still be visible in the Spring - photo: Vicky Spelman
<<“This is not to be confused with Fall needle drop.  Spruce trees often get attention in the fall. Their inner needles turn yellow or brown and drop off. To put your mind at ease, it’s not unusual for these conifers to shed interior needles beginning in late summer and continuing well into fall.  This is normal evergreen behavior. 

In fact, all conifers (“evergreens”) including spruce, pine, fir, juniper and arborvitae lose their oldest needles every year. Contrary to what the name implies, “evergreens” are not really green forever. Their needles generally have a 2–4 year life span, although spruce trees live about 5-7 years”. ~Mary Small, CSU >>

Overly dry trees can become highly susceptible to root and branch die-off, as well as more prone to insects and diseases. The best time for watering is early morning or evening to avoid the hottest times of the day, when the moisture can be quickly wicked from the ground and trees. When doing this, residents should soak the entire base of the tree slowly, to ensure deep soil penetration, and repeat this process as necessary until abundant spring rains begin to fall.

Monitoring trees for cold weather damage and keeping up with watering should maximize the trees’ health and vigor as they come out of dormancy in the spring and summer months.

For any questions, comments or concerns, please contact the CSFS Franktown Field Office at (303) 660-9625, or visit csfs.colostate.edu/franktown/.