3/03/09 WHEN SALT OF THE EARTH BECOMES SALT OF THE ROAD

Tuesday, 7:15 AM. 2 degrees, wind WSW, calm, sky mostly overcast. The barometer predicts snow.
As winter progresses, damage to roadside evergreens from road salt becomes obvious. These pines, both red and white, along Hwy. 13 at the southerly approach to Bayfield, are obviously badly damaged or dying. Salt desiccates leaf tissues, and needles being green and absorbing salt all winter , conifers are very susceptible. There are many salt tolerant species, including many that have evolved in a seashore habitat where salt ocean spray is prevalent, or were there are naturally saline soil conditions, such as desert-like areas where there is little rainfall to leach out soil salts. Salt damage is pretty obvious along roadsides, but salt spray lifted from roads by speeding cars and carried by the wind can damage conifers quite a distance from the road. Deciduous conifers such as tamarack and bald cypress are also more tolerant. There is considerable difference in salt tolerance among deciduous trees and shrubs as well, the damage obvious after the trees leaf out, the salt being taken up out of the soil by the roots. Sugar maples are notoriously intolerant to salt. Salt tolerance is a factor to be considered when planting trees along roadsides, and information is easily obtainable these days, as are most of the salt tolerant plants. Less use of road salt, and use of salt mixtures that cause less damage to plants are hopeful trends, but safety always must come first, and plantings will have to adapt.