Plants repeatedly exposed to salt over long periods of time may accumulate chloride ions to toxic levels, resulting in leaf burn and twig die- back. The injury a plant sustains increases with an increase in foliar chloride levels. Foliage in direct contact with road salt sprayed by tires and wind becomes desiccated and may appear burned. Unlike animals, plants do not have mechanisms to excrete excess salt from tissues and can only shed salt in dead leaves and needles. Because conifers do not shed leaves on a yearly basis, they tend to suffer damage from accumulated salt more easily than do deciduous trees.
Salt tolerance is directly related to the concentration of chloride ions in the foliage.
Many herbaceous plants such as grasses adapt fairly readily to high salt levels. Among woody plants, tolerance varies with the species. Plant species with waxy foliage are generally more tolerant of salt spray. In salt-sensitive plants, exposure to salt often results in an unthrifty appearance and poor growth. Other symptoms of salt injury include stunted leaves, heavy seed loads, twig and branch die-back, leaf scorch, and premature leaf drop.