“Leslie, something’s killing my pine trees. They are all turning brown, and we have to keep cutting down trees. Do you know what it is?”
My neighbor calling me gave me the first hint that something was infesting pine trees. In that moment, though, I thought hers to be a unique case. Knowing I worked as a Park Ranger for several years at Rocky Mountain National Park, she enlisted my help.
“I really don’t know. I could come over and take a look.”
It seemed to mainly afflict the Ponderosa Pines. Big trees, smaller trees, all within a fairly small area. Still, I hadn’t seen any on our property. I told her I’d check into it and get back to her.
A week later, I found out it was far more widespread. Running into another neighbor on a different road, his story seemed strikingly similar.
“Leslie, all these pine trees on Rocky Knob are dying. It must be fifty trees or more!”
During the last two weeks, I’ve noticed countless numbers of red and dead pine trees along Boulder Canyon and on the hillsides around Nederland. There seem to be more of them on south facing slopes than on the north side.
I’ve gotten a few more clues. Recently, someone told me they saw blue stains in the wood when they cut the tree down. As I’ve walked among the dead trees, their trunks glistened with thick, oozing sap.
The truth is it’s probably a combination of factors that have occurred during the last 1-2 years. Last year brought incredibly dry weather to the Colorado Rocky Mountains. Drought causes stress in a tree.
Much like people, trees need food and water to survive and even thrive. When they don’t get enough those nutrients, they become weakened and vulnerable.
Like a starving person, a tree deprived of water can’t ward off infection. Beetles and fungus can infest the tree, strangling it, cutting off its ability to access water and food. The ultimate result is death.
When a tree is trying to fend off an insect invasion, it will pitch sap out of the tree onto the trunk. When you see gobs of sap coating a trunk, it’s a pretty good sign, some insect is attacking it. Also, seeing clumps of trees is symptomatic of beetles, as they fly tree to tree, laying their eggs.
Blue stain in a cut tree tells you the tree has a fungus in it. Mountain pine beetles actually transport the blue stain fungi in their bodies, leaving it behind in the tree when they nest in the tree. In actuality, it’s not the beetles that kill the tree, but the fungus.
For every kind of conifer, there is an insect that will periodically attack it. Depending upon the population of the insects, and the health of the tree, it can cause serious tree mortality.
Once the tree dies, there are still risks. Leaving the dead snags can be dangerous especially if they are close to your home. During the windy winters around Nederland, snags are likely to be blown down.
So what’s the good news?
Usually, these insect’s population peaks, and they subside. The frequently will outstrip their food source. Also, some trees dying off isn’t the worst thing, as it usually leads to greater diversity in our local forests and better health.
In the meantime, get used to seeing lots of read, dead pine trees around the foothills.