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www.arborage.com ARBOR AGE WINTER 2015 23 INDUSTRY INSIGHTS Commission Bulletin 101," published most recently in 2011 and freely available on the web. "This is essential reading for anyone involved in selecting trees for salt tolerance and/or undertaking any form of salt related research," he said. SELECT SALT-TOLERANT TREES "Select the right tree species for the site," said Percival. "Salt tolerance varies massively between tree generations and even between species within a genus." For example, red and sugar maples (Acer rubrum and A. saccharum) are very sensitive to salt spray, but hedge and sycamore maples (A. campestre and A. pseudoplatanus) are not. Japanese black pines (Pinus thunbergii) can tolerate saline soils and salt spray, but white pines (P. strobus) tolerate neither. English oak (Quercus robur) is much more tolerant of salt that pin oak (Q. palustris). Percival describes an interesting dichotomy: "You generally find that tree species that are very tolerant of salt applied to the roots tend to be sensitive to salt applied to the foliage and vice-versa; so, when selecting a species for planting, make sure there is an appropriate species/site fit." He said that in his observation, street trees tend to suffer more from salt applied via the roots, while in more open/exposed areas, trees are PHOTO BY MICHELLE SUTTON really is not much research in this area that I am aware of. The use of calcium magnesium acetate has proved effective and far more environmentally benign than salt, but it is expensive and therefore rarely used as an option." Percival is currently evaluating the salt tolerance of many ornamental trees whose salt tolerance was yet unknown — trees that could prove useful in urban situations. "This is a joint research trial with Barcham Trees (a nursery in Cambridgeshire, U.K.) who have a phenomenal collection of trees with which to use for experimental purposes," said Percival. "The system we are using is a laboratory-based test that is rapid and effective. Data will be available very soon." SALT-WISE ACTIONS Commercial arborists can't control how their clients' municipalities run their deicing programs, but things arborists can do to help prevent or mitigate damage to trees are as follows: EDUCATE YOURSELF, YOUR CLIENTS AND LOCAL OFFICIALS Arborists can educate themselves and others about soil salinity and salt spray damage to trees. Percival recommends the bulletin, "Deicing salt damage to trees and shrubs: Forestry A surprising number of conifers can tolerate some salt exposure, but hemlock is especially intolerant. " Salt tolerance varies massively between tree genera and even between species within a genus. "