Communities filled with urban trees and lots of tree-lined streets must consider the health of their trees when it comes to spreading road salt.
Road salt can have several detrimental effects on the health of your trees, and an unhealthy tree could eventually become an expensive liability if large limbs start to weaken and fall or the overall health suffers to the point of decay.
On evergreens, damage is more obvious to the naked eye. Air borne salt residue can turn the conifers pale green and yellow the needles. Cars and trucks also can splash salt onto needles, which discolor as a result.
For deciduous trees, damage is less obvious. Salts that trickle down to tree root systems can cause desiccation (drying), which alters trees' mineral nutrition balance and soil structure.
Look for salt damage—bark discoloration and dieback—where snow has piled up near your trees to see if treatment is necessary. Treatment options are available to combat salt damage. A certified arborist can remediate the soil by drilling holes around the trees' drip lines and replacing salt-tainted soil with organic matter to provide the trees with a salt-free area in which to grow.
Think about trying a different kind of road salt. Calcium chloride based road salt may be a more expensive type of salt than sodium chloride (a more common alternative), but calcium is less harmful to plants. If you’re going to use sodium chloride, then mix it with sand, sawdust or other similar materials, which aid in traction, to reduce the amount of salt spread and lessen its negative effects on plants. Extra watering of road-side trees, when possible, can help wash away salt from tree leaves and near trunks.
Shawn Fitzgerald, Davey Institute tech advisor, recommends property owners consider applying gypsum to help protect plant and tree roots from salt damage.
Fitzgerald says property owners should apply 50 pounds of gypsum per 1,000-square-feet of turf or soil in late November or early December to shield roots.
Remember, careful planning and placement can limit all plants’ exposure to road salt.