University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Plant Damage and Deicing Salts

December 11, 1997

Certainly deicing salts are an important part of winter travel safety for roads and sidewalks. Keep in mind, however, that deicing salts also pose an environmental threat when they move off-target, such as by plowing or runoff. Among the problems is damage to vegetation.

Trees, shrubs, lawns, and other landscape plantings can be damaged by deicing salts accumulating in the soil, either deposited directly from plowing or through runoff as snow melts in spring. Diagnosing salt damage sometimes is difficult. General decline of plants can be due to a variety of factors. Location near sidewalks, roadways, and parking lots may be an indication that salts are involved, however.

As salts accumulate, plants take up chloride, which causes problems leading to dieback and decline. In addition, sodium from salts may destroy soil structure, causing more plant problems. Most damage will occur within 30 feet of the roadway or parking lot.

Salt damage depends on a variety of factors, including type and amount of salt, timing of application and species of plants. Sodium chloride, although cheaper, is more damaging to plants than sources such as calcium chloride. Only apply the amount of salt needed to do the job. Mix salt with sand (for traction). Try to shovel or plow before salting. Also, when deciding where to pile snow, note where melting snow will drain and what vegetation may be affected.

Applying gypsum to lawns is sometimes suggested to counteract the salt, but soil drainage needs to be good. Typical turf areas near roads, sidewalks, and parking lots are usually on compacted soils, which have poor drainage, limiting the effectiveness of the gypsum.

Trees can be damaged by salt spray along roadways with high speed traffic. Evergreens will show browning of foliage, while deciduous trees often show a clumping of twigs called witches brooms. This is due to buds being killed by salts settling on the branches. Temporary screening may help prevent damage. Also be aware of areas prone to salt spray when choosing plant material for these sites so salt-sensitive species are not used.

 

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