Growing Green: salt damage to trees
Winter brings frigid temperatures, icy winds and snow. Just as people battle Mother Nature at this time of year, so do trees, with one major exception: trees can’t avoid exposure to the elements.
While your trees seem to be in a state of hibernation in the winter, exposure to tough conditions can cause them major stress. Minimize that stress by helping your trees through the cold months, a little at a time. If you take care of your trees in the winter, you’ll be rewarded in the spring. Here are a few tips:
Put composted organic mulch under your tree in the fall or early winter to help retain water and reduce temperature extremes. A thin layer of mulch will act like a blanket and give the tree’s roots a little extra winter protection.
Give your trees a drink. Winter droughts require watering as much as summer droughts. If temperatures permit, an occasional watering during the winter on young trees could be a lifesaver. But be sure to water only when soil and trees are cool, not frozen.
Prune your trees. Winter is one of the best times to prune because it is easiest to see the structure of your trees without their leaves. Limit your pruning to deadwood and poorly placed branches in order to save as many living branches as possible.
Prevent mechanical injuries. Branch breakage or splitting can be caused by ice and snow accumulation or chewing and rubbing by animals. Prevent problems from occurring on young trees by wrapping the base of your trees in a hard, plastic guard or a metal hardware cloth.
Wrapping trees with burlap or plastic cloth also can prevent temperature damage. Remember to remove the wraps and guards in the spring to prevent damage when the tree begins to grow.
Salt is great for clearing roads and sidewalks of ice and snow in the winter, but too much of a good thing for streets and walkways can be downright rotten for your trees. Excessive exposure to salt can cause widespread damage to your trees, leading to permanent decline and sometimes death.
The problem with salt damage is that it might not show up on your trees until summer, when deicing salt is the last culprit you would suspect. The symptoms of salt damage are stunted growth; yellowed foliage with brown edges; brown, scorched foliage, or yellowing and withered evergreen foliage.
To minimize the damage done to trees by deicing salts, follow these tips:
Use less salt. Mix deicing salt with abrasives such as sand, cinders and ash or use alternatives such as calcium magnesium acetate and calcium chloride.
Protect your trees from salt trucks on the street. If possible, set up barriers between the street and your trees to keep salt spray from hitting tree trunks.
Improve soil drainage. Add organic matter to your soil to help filter salt deposits.
“Growing Green” is contributed by Lehigh County Extension Office Staff and Master Gardeners. Information: Lehigh County Extension Office, 610-391-9840; Northampton County Extension Office, 610-746-1970.