May 09, 2020

'Winter Burn' on Ponderosa Pines

Ponderosa pine with winter burn "Needle drop" is normal with ponderosa pines and other conifers. The pine's needles last two or three years before falling off in a normal way and becoming "duff" on the forest floor. Usually the dead needs fall from the interior of the canopy while new growth occurs at the tips of branches.

On this pine, however, and some growing near it, you can see that the dead, yellow needles are at the tip. A recent news release from the Colorado State Forest Service suggests a reason:
A cold snap in October, coupled with last week’s [mid-April 2020] 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.
I  don't live in one of those counties, which include the part of the Black Forest area NE of Colorado Springs, called that for its stands of pine trees. But we had the weather: On April 14, a neighbor's weather station recorded a low of 2° F. (-16° C), following a week of warm temperatures.
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.
The tree I photographed is rooted in a small gully, which means it gets a little more moisture, so it has grown taller than the pines around it. On the other hand, that gully is a conduit for cold air rolling down the slopes.
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.” 
Some others are showing dead needles that might mean more pine beetle kil/fungus infection. We don't lose whole mountainsides of trees, as has happened with the lodgepole pines further north. It's more a question of a few here and a few there. There is not much I can do about that. The standing dead trees mostly become firewood.

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