Deicing Salt and Trees

With the new ice coming, I thought it would be a good idea to update and repost this article I wrote; As all the snow and ice starts to melt over the next few days, the next worry is having your trees get flooded!


It’s snowing in the Lehigh Valley (Eastern, PA) and thoughts of shoveling and plowing are dancing in everyone’s head. It’s only natural to want to do as little of these activities as possible and that’s where the application of de-icing salt comes in. The more we salt and sand the walkways and driveways, the less shoveling we may have to do! As we get knee deep into the snow and sleet season, it’s a good time to talk about salt injury to your plants.

As you might expect, the damage is more common along walkways, driveways and roadways, but what exactly is salt anyway?

Salt (NaCl; sodium chloride) is commonly applied as a deicing mixture on streets and sidewalks and can cause damage to many of your trees and shrubs. The damage results when salt, dissolved in runoff water, either enters into the root zone or comes in contact with foliage in the form of spray created by passing vehicles. Symptoms of salt injury may not always be well-defined and often resemble those caused by other adverse environmental factors, particularly drought or air pollution. Affected plants commonly exhibit some or all of the following symptoms:

  • Delay in leaf budbreak flowering
  • Stunted foliage
  • Reduced shoot growth
  • Leaf and Needle browning.

Injury is most pronounced on the side of the plant facing the salt source and, particularly on evergreens, on lower branches that can get “salt spray” from passing traffic. Salt causes a “burn” to the roots and foliage it comes in contact with. This results from the natural movement of water from an area of lower salt concentration within plant cells to one of higher concentration in the soil or on foliar surfaces – causing the water to be literally “pulled out” of the plant. Another way that salt is considered to be harmful to plants is in the sodium ions themselves. Sodium concentration in plant tissues may alter a plant’s mineral nutritional balance and inhibit protein synthesis and other biochemical processes.

As you can see, most of the symptoms become obvious in the spring, so prevention is the best strategy. When shoveling snow, try not to pile it up near the root system of a tree – this might be the best prevention stratgey of all! If you do see any symptoms like the ones noted above – the first step is to water deeply and try and leach out any salt; the second step is to call your Arborist!

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