MileOne

By Richard Jauron

   While de-icing materials improve travel conditions, they can damage automobiles, concrete surfaces and landscape plants. De-icing salts can damage landscape plants when excessive amounts accumulate in the soil. The most serious damage typically occurs near major streets and highways where salt from runoff accumulates in the nearby soil.

   Excessive use of salt by homeowners also can create other problems. Trees, shrubs, perennials and turf grasses are susceptible to salt damage. Additionally, spray from passing vehicles can damage roadside plants, particularly evergreens.

   Salts affect plant growth in several ways. When high levels of salt are present in the soil, plants are unable to absorb sufficient water even though soil moisture is plentiful.
Plants suffer a salt-induced water shortage termed "physiological drought." High levels of salt restrict the uptake of essential nutrients by plant roots. Excessive amounts of sodium and chloride ions in plant tissue are toxic to many plants. High sodium levels damage soil structure. Salt deposited directly on plant foliage can cause dehydration of plant tissue.
   The symptoms of salt injury to deciduous trees and shrubs include stunted growth, marginal leaf scorch, early fall coloration and twig dieback. Accumulation of salt in the soil over several years might result in progressive decline and eventual death.

   Salt damage to evergreens results in yellowing or browning of the needles and twig dieback. Evergreens near heavily salted roadways are often damaged by salt spray.