24 WINTER 2015 ARBOR AGE www.arborage.com
INDUSTRY INSIGHTS
more susceptible to foliar salt spray. The Virginia Cooperative
Extension (VCE) bulletin, "Trees and Shrubs that Tolerate
Saline Soils and Salt Spray Drift," provides a long list of trees
that teases out the kind of salt tolerance each species possesses.
SITE THE SENSITIVE ONES
The VCE bulletin advises arborists to plant trees sensitive to
soil salinity on berms or uphill so that gravity works to keep
the salty water away from tree roots. Trees that are sensitive
to both soil salinity and spray should also be planted at least
50 to 60 feet back from surfaces that are commonly deiced.
Arborists can group salt-tolerant species in such a way as to
protect the salt-sensitive species behind them from salt spray. To
accomplish this, there is also the option of fencing to provide a
physical barrier between salted roads and treasured trees.
COAT THE LEAVES
Percival and a colleague have done research on film-forming
polymers. "These are specially derived polymers that are
designed to be sprayed onto tree foliage that, in essence, act
as a salt-protective barrier across the leaf or conifer needle
surface, and prevent salt ions entering the plant," he said.
Field trials by Percival and others showed that these newer
polymers, unlike those of the past, also have no detrimental
effects on tree biology, and that their protective effects last up
to three months per application.
APPLY SUGAR BEFORE SALT
In another study, Percival and Al-Habsi Sulaiman found
that the salt tolerance of trees can be artificially enhanced by
applying sugars to their root systems before salt is applied.
"Admittedly, it's a little out of left field," said Percival; but for
the two species they studied, application of sucrose, which
can protect leaf cellular structure, induced tolerance to and
recovery from de-icing salt damage. It's an intriguing finding
worthy of more study with more tree species.
IMPROVE SOIL AND INCREASE SOIL VOLUME
Where there is more organic matter, there is better soil
structure, and where there is better soil structure, there is
Baldcypress trees are observed to have some tolerance to both soil
salinity and salt spray.
Ginkgo trees are observed to have some
tolerance of salt spray.
PHOTOS
BY
MICHELLE
SUTTON
