Trees and shrubs: With recent snowfalls, many of us may be using deicing salt products to keep driveways and sidewalks clear. However, we all need to be careful about using deicing salts on driveways or sidewalks. Excessive use of salt is not a good thing for our soils or lakes and streams. Excess sodium in the soil leads to reduced water infiltration and soil compaction, among other things. After years of salt build-up in the soil, plants can be stunted or die. Plants that receive salt spray from passing vehicles on a constant basis are especially prone to damage. Some symptoms of damage include dead twigs (and dead needles on evergreens), leaves with brown margins, dead buds and formation of “brooms” (tight clusters of short twigs) on branch ends or along branches and reduced leaf size. If possible, in locations near plants, don’t use deicing salt alone, but mix it with sand or use an alternative product that is not pure sodium chloride (NaCl), such as calcium chloride. It does tend to be a little more expensive, but is better for the environment and your plants. Laura Jull of the UW-Madison Horticulture Department wrote a detailed publication on the effects of salt on woody plants and also recommends some salt tolerant species for places where deicing salts are needed for winter pedestrian or vehicular safety. It is titled “Winter Salt Injury and Salt-Tolerant Landscape Plants.” You can find this free printable article at https://learningstore.uwex.edu/ — type A3877 into the search box. The city of Madison has started a certification program for winter maintenance crews who serve homeowners, corporations and municipalities. It focuses on how to use the least amount of road salt possible and still maintain safety in winter.
Lisa Johnson, Dane County UW-Extension horticulture educator