By Bill Snyder
In our northern climate, chemicals are applied to our paved surfaces to prevent the formation of ice (anti-icing agents) or to break up ice that has already formed (de-icing agents).
The majority of ice-treating materials are salts that act by lowering the freezing temperature of water below 32 degrees.
These are usually the chloride salts of sodium, calcium, potassium and magnesium. Sodium chloride, the major component of rock salt, is the most inexpensive and most commonly used.
Abrasive materials like sand, cinders and sawdust are sometimes added to improve traction, but without providing any significant melting.
When de-icing salt runoff accumulates in nearby soil, the result can be salt damage to trees, shrubs, perennials and turf grasses.
Also, spray from passing vehicles can damage roadside plants, especially evergreens, by causing browning through dehydration of the needles. This damage may not become apparent until the following summer.
When salt accumulates in soil, the water-absorbing properties of these salts can keep valuable moisture from plant roots. The water is not only important for the plants over the winter, but also reduces the plants’ ability to absorb necessary nutrients from the soil.
In addition, uptake of sodium chloride into plant tissue can be very toxic, depending on the species of plant.
If you use rock salt, stop applying by late winter. When plants begin to break dormancy in late March, the roots need to absorb water and nutrients.
Homeowners can prevent damage by using de-icing salts carefully.
Keep in mind that calcium, potassium and magnesium salts are usually less toxic to plants than sodium chloride. It is better to use amounts necessary to loosen and remove ice and snow with a shovel instead of trying to apply a sufficient amount to completely melt the ice.
Mix the salt with an abrasivelike sand to limit salt concentrations and avoid placing salt-laden snow around trees and shrubs.
You can minimize damage to surrounding property by heavily watering the area as soon as the ground thaws. A thorough soaking will help to wash the salt from the root zone of plants.
For an extensive list of landscape plant sensitivities to salt, visit go.osu.edu/saltdamage.