The first time you see rows of trees with bright white trunks, it may look like decoration or a way to mark property. In reality, the coating has a practical purpose: protecting trees from winter damage. The simple treatment helps prevent a condition called sunscald, which can seriously weaken bark.

During cold weather, sunlight can warm one side of a tree trunk while the rest remains frozen. When temperatures suddenly fall after sunset, the warmed bark cools too quickly, creating stress that can cause cracks and splits. “The damage caused by rapid temperature changes is known as sunscald.” These injuries can leave trees vulnerable to insects, fungi, and disease.

To reduce this risk, farmers and gardeners often apply diluted white latex paint to the lower part of the trunk. The white surface reflects sunlight instead of absorbing it, helping keep the bark at a steadier temperature throughout the day. This reduces the sudden heating and cooling that can lead to winter injuries.

Young and newly planted trees benefit especially from this protection because their thinner bark is more sensitive to temperature changes. Fruit trees, ornamental trees, and young shade trees are commonly treated before winter. Tree wraps can also provide similar protection when paint is not preferred.

Rather than being decorative, the white coating works much like sunscreen for a tree. “The practice is inexpensive, easy to apply, and highly effective when done correctly.” So, the next time you see white-painted tree trunks along a road, in a park, or in an orchard, you’ll know that the coating is there to help protect the trees and keep them healthy through harsh winter conditions.