Utah trees, the winter damage that can impact them, and how to combat it

SALT LAKE CITY — Winter can be a difficult time for the entire landscape, and trees and shrubs are no exception. Frozen ground, drought stress, rapid temperature swings, and wildlife damage can all take a toll during the winter months.

One common winter issue is leaf or needle browning in conifers, such as pines, spruce, arborvitae, and junipers, and in broadleaf evergreens like laurels, boxwood, euonymus, and photinia. This often occurs when the soil is frozen deeply, but daytime temperatures rise above freezing, especially on sunny days.

Plants continue to lose moisture through their needles and leaves, but frozen soil prevents roots from taking up replacement water. The result is browning at branch tips and, in severe cases, branch dieback.

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The same type of injury can occur when plants enter winter already drought-stressed. A key preventive step is to irrigate trees and shrubs deeply in the fall before soils freeze. During extended dry periods in winter, additional irrigation may be needed, particularly for newly planted trees, shrubs, and perennials.

In cold, windy locations, such as Evanston, Wyoming, antidesiccant sprays are sometimes used on conifers to reduce moisture loss. Salt used to melt ice also causes similar damage in plants. Avoid applying salt under the canopies of trees and shrubs.

Rapid temperature changes can also cause serious damage. When temperatures plunge below zero, water inside trunks and limbs can freeze and expand, causing cracks in the trunks and limbs and conductive tissue damage or death.

Sunscald is another common problem, especially on the south and west sides of trees. Winter sun warms the bark during the day, triggering sap movement, which then freezes at night and damages conductive tissue. This often causes bark to split or slough off. Wrapping the trunks of young trees with fabric tree wrap in the fall and removing it in spring can help prevent this injury. Continue wrapping until the tree develops thick, corky bark.

Winter and wildlife damage

Finally, winter is peak season for wildlife damage. Deer, rabbits, voles, and other animals frequently feed on bark when food is scarce.

A simple and effective strategy is to place metal mesh or hardware cloth around tree trunks to prevent chewing. This should be temporary, as leaving it on too long can restrict trunk growth.

Repellents—homemade or commercial—may provide limited protection, but hungry animals often ignore them. While some extension sources suggest providing alternative food, this can attract even more wildlife.

The most reliable solution is exclusion. Fencing individual areas, such as orchards or vegetable gardens, is often more practical than fencing an entire yard.

For deer, fences should be at least eight feet tall. Utah State University Extension also provides fact sheets on managing damage from squirrels, skunks, raccoons, and other wildlife common to Utah landscapes.

With a little preparation and vigilance, you can reduce winter damage and help your trees emerge healthier in spring.

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