If traces of rock salt find their way to the foliage, it becomes desiccated. Some trees absorb the sodium and others suffer from root damage when salt seeps into the soil.

Evergreens, including conifers, pines, spruce and holly trees, are the most susceptible to damage. Fraedrich says soil damage results in significant drooping of the tree, especially at the top, as salt inhibits absorption of water by the root system.

Salt damage produces similar symptoms as drought. Airborne salts (from vehicles) tend to make for thinner leaves and later spring blooming. Stunted growth or browning of foliage, thinning of branch tips, premature fall coloration, defoliation and dead branches are other symptoms. Severe cases often lead to insect infestation.

You can divert salt sources from trees by erecting barriers of burlap or wood, lay down mulch to prevent seepage and thoroughly water during dry periods.