Homeowner Alert

Tree Damage Caused by Chemical De-Icing Products

Road salt use in the United States was once considered the best method for de-icing roads and walkways.

De-icing chemicals were economical and considered to be the most effective method of making iced roads and walkways safe for use.

December 2013 Fairfax County Urban Forest Management Division,

Public Works and Environmental Services, Fairfax County, Virginia

1950 to Today Salt Use

• In 1950, fewer than 2 million tons of salt were used on US highways

• In 1988, about 10 million tons of salt were used on US highways

• Today, there may be as much as 20 million tons of sodium chloride (salt) spread or sprayed on highways each winter in the US

Anti-Icing• In some areas of the US, brine is used.

This is a mixture of rock salt and water. Applying brine before a snowfall, may prevent snow and ice from sticking to roads. This is known as anti-icing.

• The use of brine dramatically reduces the amount of salt needed and the time it takes to remove snow and ice from roads, according to the Conservation Law Foundation.

• For questions about substances uses on Virginia roads see VDOT.

• Products used for de-icing include calcium chloride and magnesium chloride

• These products are more expensive than traditional rock salt

De-Icing

Salt is Harmful to Trees

• Trees absorb salt through the air and soil when roads, sidewalks and driveways are spread or sprayed with salt

• Salt spray may travel 50 feet from the road

• Salt in the soil may create a physiological drought

• Tree roots cannot take in water

• A tree under stress from an overload of salt is “dying of thirst”

Salt is Harmful to Trees• The chloride in salt

may be taken up by tree roots, enter the sap, concentrate in the shoots and prevent buds from opening

• Salt restricts the ability of the tree to take up magnesium and potassium that are essential for making chlorophyll

Prevent Salt from Reaching Trees

Use salt alternatives on sidewalks and driveways• Non-sodium de-icing agents such as calcium chloride or

calcium magnesium acetate (CMA) • Other salt-free melting agents made from limestone and

acetic acid• Non-clumping cat litter or wood ashes• Coarse sand

• Cover trees with burlap if they are close to a road that may be salted• Erect barriers at road side with plastic fencing, burlap or snow

fencing

How to Diagnose a Salt Damaged

Tree**• Conifers that have been injured by salt show the damage in early

spring• Needles become yellow or broken, may drop off• Some needles may turn blue-green

• Deciduous trees develop a tuft called a “witch’s broom”• Flower buds may not open• Leaves may appear to be scorched or burned• Leaf margins turn brown prematurely

Generally, salt damaged trees have sparse foliage, may be stunted or yellow, and twigs may die back.

** Yates County Master Gardeners, Cornell University

How to Treat A “Salty” TreeIn the spring:

• Remove the mulch from around the tree and discard; mulch can trap a large portion of winter salt

• If drainage is good, wash the salt away from the top 18 inches of soil around the tree by watering thoroughly

In general:• Improve drainage around the tree roots• Avoid salting when trees are active in the fall and spring• Fertilize properly and only when necessary; carefully follow

directions on the package – more is not better!• Dormant trees are less likely to be harmed by salt

Plant Salt Tolerant Trees

Plant salt tolerant trees at least 30 feet from salted surfaces such as roads, sidewalks and driveways.

For a list of salt tolerant trees visit the Virginia Cooperative Extension

Young trees, with fewer roots, are more susceptible to salt injury.

Hedge maple Acer campestre

Hackberry Celtis laevigata

Fringetree Chionanthus virginicus

Ginkgo Ginkgo biloba

Several species are:Hedge maple Acer campestre

Hackberry Celtis laevigata

Fringetree Chionanthus virginicus

Ginkgo Ginkgo biloba

Southern Magnolia Magnolia grandiflora

For more information or to request this document in an alternate format call or email the Urban Forest Management Division, Department of Public Works and Environmental Services12055 Government Center Parkway (Herrity Building)Fairfax, Virginia 22035703-324-1770 TTY 711treemail@fairfaxcounty.gov

A Fairfax County, Virginia publication December 2013

Thank you.