Winterburn on Evergreens

Modest winterburn
Modest winterburn
Severe winterburn

We are starting to get calls about concerns people have for evergreen trees and shrubs with needles that are turning brown, which is a condition called winterburn.  Winterburn is generally worse in years when there has been a really long period of snow cover, especially if continuous snow cover has existed for more than 60 days.  This winter, I think we have had 100-120 days of snow cover, so winterburn is probably going to be widespread on susceptible varieties.

The evergreen shrubs and trees most vulnerable to winterburn are those most recently planted that do not yet have a large and well established root system.  White Pine, Red Pine, Scotch Pine, Austrian Pine and some varieties of Arborvitae develop winterburn more easily than the other evergreens.  The bad news is that winterburn is an issue once every few years.  The good news is that most trees that look poorly i the spring will push out nice new growth in May or June, and will look good again in a relatively sort period of time.

Sometimes selected twigs/branches may get dried out enough to kill the twig/branch.  If this happens – wait until mid to late June before pruning out twigs you think are dead, to give them a chance to sprout new growth if the damage is light enough.

Most winterburned evergreens will make a comeback.  In cases where damage is extensive, a decision will have to be made to work with a tree or shrub that is misshapen, or to remove and replace.  It’s all a matter of degree, and what each property owner finds tolerable.

In years like this when winterburn is fairly widespread, I’m always amazed at how terrible an evergreen tree or shrub can look and still make a good recovery.  If needles brown out, but the surface of the twig is not shriveled, a good recovery is possible.  When the bark of a twig is shriveled the twig is probably dead, and it may be time to make plans for replacement.