The damage is thought to be caused by a combination of desiccating winds, winter sun, and widely fluctuating temperatures. The dry conditions that have prevailed over large areas of Iowa over the past two years may also have played a role. While the browning of needles normally shows up in March and April, this winter it began to appear in January. It has become progressively more widespread over the last few weeks. Browning of evergreen foliage can be seen on pines, yews, arborvitae, firs, and spruces.
Damage is most evident on the south and west sides of trees and shrubs.
The brown needles on affected trees and shrubs have been destroyed and will eventually fall off. Fortunately, the buds on most damaged evergreens are still alive and will break bud and produce new growth this spring. The affected trees and shrubs should look much better by late June or July. There is no need to fertilize affected evergreens. However, if the weather this spring is dry, periodically water the trees and shrubs to encourage new growth and speed their recovery.