Every spring, gardeners and homeowners survey how trees and shrubs survived the past winter. As I drive around each spring, I notice the red/brown foliage and I assume its winter damage.
According to Janna Beckman, extension plant pathologist, winter damage is not always the cause. The real culprit can be the result of dryness in the fall and winter. This affects the needles throughout the entire tree, and the needles dry out and fall off. This develops when warm air temperatures trick the tree into becoming active. Although the winter was not dry, the fall was extremely dry and conifers take moisture all winter long.
As the tree loses water by transpiration, the roots are still frozen and water can’t get through to the foliage to replace the lost moisture. This causes the needles to dry and as the needles dry, they turn reddish-brown in the early spring.
Most plants will show symptoms evenly throughout the tree. Plants exposed to extreme temperature fluctuation, strong winter winds, or direct sun from the south or west-facing sides are more severely affected. Evergreens in windbreaks, with a southern or eastern exposure, regularly have winter injury every year. Trees planted too deeply, too close together, or in poorly drained soils are all susceptible to developing winter injury.
If there are brown, dead-looking needles on your evergreens, there’s good news and bad news. The bad news is the brown needles are dead. If a tree or shrub is brown from top to bottom, go to a nursery or garden center and buy a new one. The good news is that although many pines, junipers, cedars, spruce and arborvitae may have spots with brown needles, you don’t need to get out the pruning shears just yet. Experts say it’s very likely that these plants will recover.
Depending on the type of plant and the severity of the damage, new growth will develop, and that the time to prune out the dead needles.