Have you ever been driving down Boulder Canyon, seeing a pine tree with brown needles, and thinking “I thought those were supposed to stay green all year long. What’s up with that?”
Although these trees are evergreens, sometimes they don’t get enough water. During the summertime when the sun’s hot and drying out everything it touches, these trees will try to preserve the water they have, which can cause needles to turn brown. In the wintertime, pine trees transpire (give off water vapors through pores) from their needles, which results in some water loss, but this is sped up by dry winds and the roots freeze and are unable to take up more water.
In the winter, walking around Nederland, or even just walking up to the school, you can see blue salt crystals all over the ground to melt the snow and ice. As it turns out, this compound of magnesium chloride could be harmful to plants if it seeps into the ground. A Colorado State University article written in 2008 and last revised in 2014 states, “Chloride (Cl- ) and magnesium (Mg+2) are both essential nutrients important for normal plant growth. Too much of either nutrient may harm a plant…or change water relationships such that the plant cannot easily accumulate water and nutrients.” These toxins may end up killing leaves, which in turn kills the tree since a lot of the processes the tree undergoes, like photosynthesis, happens in the leaves.
Another cause for the discoloration of pine needles is dothistroma septosporum, or dothistroma needle blight, which is a fungal infection that may turn pine needles brown and cause them to fall off. It is spread when spores are produced in cold, wet weather and then spread with the help of wind. To help control, and somewhat treat already infected pines, a copper fungicide is used. Copper is the active ingredient in these fungicides, which kills the spores so they can’t germinate, meaning they can’t grow.
Pine beetles also have a role to play in the browning evergreens. These beetles carry a fungus, which is what primarily kills the trees. These beetles also dig tunnels in pines, which then blocks food from flowing from the pine needles to the roots. Solutions consist of removing infested trees and setting up trap trees to trap emerging adult beetles.
There’s not many ways we can combat nature, but if we do it carefully we can slow the dying of evergreen trees.
