Evergreens like pine, fir, spruce, and juniper trees are supposed to proudly display healthy green needles throughout the year. So if your trees are turning brown, you may have some concerns. Often, the problem is just temporary, but there could be some simple solutions if you know what to do. Here are five reasons why your evergreen may be turning brown, and how you should handle it.
Lack of Water
Evergreens face challenges that many other trees don't. But they also have a few clever ways that they meet those challenges, one of which is how they obtain water in the winter.
Since the ground freezes and water sources can be scarce in cold climates, evergreens store water in their needles so they have an abundant source of hydration during the winter. But as you may have guessed, that above-ground water source could dry up, causing the needles to brown.
To prevent this from happening, you can have an anti-desiccant spray applied to the needles—a waxy coat that helps to prevent the loss of moisture. This should be done no earlier than December, when the temps are between 40 and 50 degrees, and when it's not expected to rain for several days. Also, watering your trees on a monthly basis can help, but only when it's above freezing outside.
Freezing Temps
Evergreens don't always adjust to rapid drops in temperature. Ideally, they should have a little time to prepare for the change. This process, known as acclimation, is a delicate act involving physiological processes that aren't yet fully understood. Suffice it to say, as the days get shorter and the temperatures slowly drop, hormones are released inside the tree that change the membranes around the cell, making it more flexible and therefore more resistant to freezing.
If the temps drop too quickly, acclimation doesn't occur, and ice crystals will form, killing the cells inside the tree. When this happens, brown needles will be more noticeable on the ends of the branches since they are the ones more exposed to the cold, and the needles closer to the trunk will still be green.
The best thing to do in this case is to check the buds on the tips with a light pinch. If they don't crumble between your fingers, then the branch is probably still healthy and will have new growth in the spring. If the bud crumbles, you can prune it back, removing the dead part of the tree so that the healthy sections will have ample sun when the seasons change.
Needle Cast
If the needles on the inside of the tree are turning brown, but the ends of the branches are still healthy and green, then your evergreen is probably going through "needle cast." Just think of this as an evergreen's version of dropping leaves in the fall. This is perfectly normal and doesn't require any sort of treatment or attention.
Sun Scald
If the temps are extremely low, you have an unusually dry winter, and your tree is exposed to a great deal of sun, it can experience sun scald. Usually this results in just the tips of the needles turning brown. Also, if part of the tree is shaded, the needles on the sunny side will be the only ones affected.
This usually isn't enough to kill a tree, but you can sometimes ward it off with a regular watering cycle or the application of an anti-desiccant. If you have the time and inclination, you can erect a burlap wall next to the tree that acts as a barrier to the wind and sun.
Be sure to remove any damaged bark during the spring so that healthy, new growth can occur.
Pests
Certain pests can wreak havoc on an evergreen. Bark beetles, weevils, and the pine wood nematode are just a few examples of insects that can cause serious problems, but they can vary based on where you live.
Browning needles, small holes in the trunk, and the presence of sawdust and leaking sap near canker spots are all signs that the tree is in danger. Identification and treatment usually requires the skill of a landscaper or arborist. So if you notice any of the above symptoms, it's best to call a professional tree service as soon as possible.
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