Sidewalks and driveways can be hazardous when covered with snow and ice and de-icing salt is widely used to help remove them. Safety is important but it should also be remembered that ice-melting materials may cause severe injury to lawn grasses, shrubs and trees.
Although the plants are dormant during the winter the roots still are active. The salt solutions that drain from or are swept off melting walk-ways may penetrate the soil around plant roots. The salt accumulation in the soil results in roots losing large amounts of water to equalized the salt concentration.
This phenomenon is the result of osmosis. The water already existing in plant roots will move out through root membranes in order to dilute and equalize the salt concentration in the soil.
Damage to plants takes many forms including stunting, poor growth and death. However, the same problems can be caused by drought, compacted soil, planting tree or shrub too deep, improper fertilization and several kinds of diseases.
Usually plants weakened by high salt concentrations are more susceptible to diseases which would not be serious if they were in good health.
The best way to avoid salt damage is to use minimum amounts and be careful when applying it near grass, trees or shrubs.
Don't try to melt six inches of snow s with salt. Shovel first. The salt should not be washed or shoveled off the pavement after snow and ice are melted. Leave it there, ready for the next snowfall. If you do have to shovel the salt, put it some place where it will do the least harm.
Plants most likely to be damaged by salt include roses, boxwood, black walnut, red maple, sugar maple and bluegrass. Kentucky 31 fescue and Bermuda grass have considerable tolerance.
A light sprinkling of granular nitrogen fertilizer could be as effective as salt. Heavy applications, however could cause nitrate pollution and the cost of the fertilizer would be rather high.
All across the country increased use of salt on roads in winter is detroying nearby trees and shrubs. Most noticeable injury to roadside trees occurs at school and commercial bus stops and low places where salt is washed down to tree roots.
Along highways vehicles splash salted slush for quite a distance particularly when the wind is blowing. Trees up to 30 feet from a highway have been crippled when salt seeped through to their roots.
Without adequated plant cover, the soil has eroded, increasing the rush so soil-laden run-off water into drain sewers. The soil has clogged the sewers and back-up water has become a problem.