These articles are written to apply to the northeastern
corner of Illinois. Problems and timing may not apply outside of this
area. |
Consider Adjacent Plants
When Using Deicing Salts
December 9, 1999
A dusting of snow this weekend reminds us it is December, and significant
snows may not be far off. While deicing salts are important tools to help
assure safer foot and vehicle traffic in the snow and ice, their use can
also damage plantings. Here's my annual column on use of deicing
salts and considerations concerning adjacent landscape plantings.
The most common deicing salt material, sodium chloride, damages plants
in two ways. Plants may take up chloride from salts accumulating in the
soil, which can lead to dieback and decline. Sodium from salts may destroy
soil structure, causing more plant problems. Most damage will occur within
30 feet of the roadway or parking lot. Along high-speed roads, salt may
also drift onto vegetation, causing "witches brooms," or clusters
of twigs at the ends of branches. Evergreens tend to turn brown when salt
settles on their foliage.
In residential areas, trees, shrubs, lawns, and other landscape plantings
are most often damaged by deicing salts accumulating in the soil, either
deposited directly from plowing or through runoff as snow melts in spring.
Diagnosing this salt damage can be difficult, as decline, lack of vigor,
and many other things could also cause dieback attributed to salt damage.
If declining plants are located near sidewalks, roadways, or parking lots,
consider deicing salts as a potential source.
Salt damage experienced by plants 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, consider where
snowmelt goes and vegetation that may be affected when deciding where
to pile snow.
Applying gypsum to lawns is sometimes suggested to counteract the salt,
but good soil drainage is needed. Typical turf areas near roads, sidewalks,
and parking lots are usually have poor soil drainage, limiting the effectiveness
of the gypsum. Along highways, temporary screening may help prevent damage to trees
and shrubs. Also be aware of areas prone to salt spray when choosing plant
material for these sites so salt-sensitive species are not used. |
