The winter of 2014 took a great toll on evergreens in northern Illinois, said a University of Illinois Extension horticulture educator.
“Just driving down the highway, you can notice browning on a good portion of evergreen shrubs and trees. This browning can be called winter burn or dessication,” said Candice Miller. “Because evergreens retain their leaves throughout the winter, they are susceptible to a variety of winter related problems. And because the leaves on evergreens are still green and living, they need to be able to use and take up water from the soil.”
Dessication happens when cold winter winds blow past evergreens and pull moisture out of the leaves faster than the plant can replace the moisture. If the ground is frozen and the plant cannot take up enough water, the leaves brown as a result. This typically shows up on the windward, sun-exposed side of the plant and is not uniformly spaced around the plant. This can happen on young as well as old trees and shrubs, Miller explained.
The other possible cause of browning on evergreens could be from salt spray. This browning can occur on evergreens that are close to sidewalks and roadways where de-icing salt may have splashed on the plant. Because salt draws water from plant tissue, this salt spray can cause winter burn. This again will appear on only the side of the tree closest to the sidewalk or street.
“Luckily, many times an evergreen come overcome this damage if it just occurs on a portion of the plant,” Miller noted. “They just need some time to recover.”
This spring and summer, the evergreen will start to put on new growth in the areas where it was not too badly damaged. Gardeners can prune off the brown foliage, or it will fall off naturally as new growth starts. If no growth has come from a branch by June, it’s likely that the branch was too badly damaged and will need pruned out, Miller said.
To prevent this problem next year, Miller recommends making sure evergreens are well watered in the fall going into winter.
“Anti-dessicant sprays can also be purchased and applied following the label’s directions next season, and a burlap wrap around the plant can also deflect some wind,” she said.