The rock salt used to melt ice and snow on the roads and walkways, typically sodium chloride, can have a devastating impact when it comes to the growth and overall health of trees and shrubs.
Rock Salt hurts trees in two different ways; when it comes in contact with the above-ground portion of the tree, and when it enters the soil. When salt is splashed onto the trunk, bark, and leaves of the tree it can cause salt burn and pull the water out of the needles, buds, and branches leading to dehydration and the exposure of tender developing tissue.
When the road salt enters the soil in high concentrations it will displace other nutrients in the soil and lead to the roots absorbing what is left, sodium and chloride. This will lead to nutrient deficiencies and can interfere with photosynthesis and chlorophyll production. In toxic levels, it will also cause leaf burn and dieback. In smaller concentration, rock salt will pull water out of the tree’s roots dehydrating the tree even more; also known as Chemical Drought.
Signs Of Rock Salt/Ice Melt Damage On Trees?
On Evergreens you will likely start seeing the effects of salt damage in late winter; however, deciduous trees will not show damage until growth resumes in the spring. Look for the common warning signs below:
- Damage mostly on the side of the tree facing roads, sidewalk, and driveway
- Browning or discoloration of needles beginning at tips
- Marginal Leaf Burn: Browning or discoloration along the edges of leaves.
- Fewer and/or smaller leaves than normal
- Flower and fruit development delayed/smaller than normal
- Bud damage/death
- Twig dieback
- Delayed bud break
- Reduced plant vigor
- Discolored foliage
- Early leaf drop or premature fall color
Trees Highly Susceptible to Rock Salt Damage:
Red Maple, Sugar Maple, Boxwood, Dogwood, Black Walnut, Norway Spruce, Eastern White Pine, Douglas Fir, Pin Oak, Littleleaf Linden, and Eastern Hemlock.
Rock Salt Tolerant Trees:
White Oak, Northern Red Oak, Paper Birch, Colorado Spruce/Blue Spruce, Juniper, Mugo Pine.
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Ways You Can Avoid Salt Damage on Trees This Winter:
- Don’t Use Salt: Do not lay down salt anywhere near your trees and landscape plants.
- Choose Something Other Than Typical Rock Salt: If you can’t avoid placing salt near your trees, opt for calcium chloride, magnesium chloride, potassium chloride, or calcium magnesium acetate (CMA). These are more expensive than typical Rock Salt (Sodium Chloride) but are friendlier to trees and landscape plants.
- Install A Barrier: If you don’t have control over what type of salt your trees/plants are exposed to, install a barrier between your yard and roads/walkways that use salt. Try snow fencing or planting a barrier of salt-resistant trees.
- Treat With Anti-Desiccants: Anti-desiccant form an invisible protective coating on leaves helping protect them from winter burn and rock salt damage.Learn More About Anti-Desiccants!
- Rinse Your Trees: In the spring, once temperatures are above freezing rinse of all trees and plants near salted roads, sidewalks, and driveways. Then water them thoroughly to dilute leftover rock salt.
As winters become harsher and snowier in the Northern VA, DC, and Maryland area, salt damage will become an increasing problem for trees and landscape plants. Make sure to protect your trees this winter. And keep in mind, if you see signs of Salt Damage on your tree in late winter/spring make an appointment to have one of our arborists check it out using our online booking system or call us at 703.573.3029.