With heavy snows comes heavy salting of roads,
resulting in subsequent damage to roadside plants. Certain preventative
measures, and selection of salt-tolerant plants, will help lessen the damage.
The symptoms of excessive salt resemble
those caused by drought or root injury. They include stunted, yellow foliage;
premature autumn leaf coloration; death of leaf margins (scorch); and twig
dieback.
When conifers are injured by salt spray,
the affected foliage turns yellow or brown in early spring. If spray is
the primary cause of the salt deposit, discolored needles are soon masked
by the new year's growth.
However, if salt is excessive in the soil,
the new needles may die as chloride ions accumulate in them. This could
be lethal to the entire plant if it occurs for several consecutive years.
One characteristic of salt injury that
aids in diagnosis is that it is often confined to branches facing the road.
Trees closer to the road suffer more damage than those set farther back.
Screens of fencing or burlap may be erected
to ward off salt spray from roads. Salt and snow should not be piled around
plants or in places where the resulting salt water will drain into plants
when the snow melts. If weather permits, it's a good idea to flush the
area around roots exposed to salt with fresh water as soon as the snow
melts.
Where new trees and shrubs are to be planted
and where exposure to salt is likely, select species or cultivars resistant
to salt injury. Examples of salt-tolerant evergreens include tamarack (larch)
and Austrian pine. Salt-tolerant deciduous trees include yellow birch,
Russian olive, honey locust, white poplar, white oak, red oak, and weeping
willow. Salt-tolerant shrubs include rugosa rose, tamarisk, tatarian honeysuckle,
and pfitzer juniper.
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University of Vermont
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