LONDONDERRY, N.H. — Each winter, vast quantities of de-icing salt are applied to state and municipal roads to keep them safe for commuters, and salt is spread near houses to avoid pedestrian injuries.
This is necessary for safety, but excessive salt can cause widespread damage to trees and shrubs — possibly leading to permanent decline and even death. Even severe salt damage might not be visible on a tree until the end of summer, leaving homeowners wondering what might have caused the problem. In some cases, decline might not be visible for years.
Salt deposits migrate to the stems, buds and roots of trees causing disfigured foliage, stunted growth and severe decline in tree health, said Tchukki Andersen, staff arborist with the Tree Care Industry Association. “Salt runoff washes from pavement into the ground, increasing salt levels in the soil,” said Andersen
TCIA recommends the following steps to ward off tree damage:
- Avoid use of de-icing salt unless necessary.
- Mix salt with abrasives such as sand, cinders and ash.
- Use alternative de-icing salts such as calcium chloride and calcium magnesium acetate.
- Improve drainage of soils.
- Add organic matter such as activated charcoal or gypsum, and thoroughly leach salt residues from the soil by flushing with water.
- Erect barriers between pavement and plants.
- Plant trees in locations away from any type of salt spray.
- Plant salt-resistant trees in areas where high salt spray is inevitable i.e., near walkways, driveways or roads.
- Provide adequate irrigation and mulching to reduce water loss.
- Prune properly and add fertilizers to correct nutrient deficiency as indicated in spring soil testing.
- Control tree-damaging diseases and pest infestations.
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