September 23, 2013 Updated: September 23, 2013 at 12:10 pm
You may have noticed that some of the needles on conifers have been turning brown, and you may have presumed that has occurred because of the early-season drought this year, or because some kind of insect is attacking the trees.
But the truth is that conifers are not really EVERgreens.
The Woodland Park office of the Colorado State Forest Service explained the natural browning of pine needles last week, noting that "although thousands of evergreen trees along the southern Front Range are beginning to display dying yellow or brown needles, most are simply going through a natural shedding process - and are not infested by bark beetles or tree disease."
Michael Till, forester at the Colorado State Forest Service Woodland Park District, said, "Fall needle cast is usually brought on by seasonal changes and weather events. We commonly see conifers shed their needles in September and October."
In a news release, Till said, "Every autumn, many Colorado evergreen tree species shed some of their older, interior needles as part of an annual growth cycle. Needles on the lower portion of the crowns or closest to the trunk are most commonly shed, but trees stressed due to drought or root damage may shed more needles to keep the tree in balance with its root system. Soon-to-be shed needles typically turn yellow first, then a reddish-brown color before dropping off; very small branches with few needles on them also may die.
It's true that the notorious bark beetle is responsible for the browning of tens of thousands of acres of Colorado forests, but Till explained that "evergreen trees that shed fall needles have a different appearance than trees infested by bark beetles. The needles on a beetle-infested tree typically change color throughout the entire tree, initially starting with an off-shade of green and turning to reddish-orange by the following summer. In addition to changing needle color, bark beetle-infested trees will show other signs of attack, such as fine sawdust at the base of the tree."
In other words, if you're worried that your pine tree has brown needles after all of the recent rains - stop worrying.
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