of Rhode Island GreenShare Factsheets
Winter injury can take many forms. It can be the result
of desiccation and temperature fluctuations or it can result
from damage due to salt, snow or ice.
Desiccation (drying out) injury usually takes place mid-January
through March, when the grounds is still frozen and plant roots
are dormant. When a thaw warms the foliage, moisture drawn
out of the leaves on sunny, windy winter days cannot be replaced
because of the frozen roots.
Desiccation is easy to detect. When the leaves dry out,
they may look scorched or yellow to dark brown at the tips,
outer margins or between the mid-rib and outer edges. The symptoms
sometimes do not become evident until early spring. Arborvitae
and rhododendrons are especially affected by desiccation.
Injury due to temperature fluctuations can result from
a loss in hardiness or from sunscald.
As fall approaches, gradully lowering temperatures harden
off (acclimatize) woody plants. This pattern reverses as spring
approaches. If temperatures fall too quickly (more than six
degrees/hour) and stay too low for a prolonged period of time,
the plants may not have enough time to harden and can be injured.
Early fall or late spring frosts cause the most damage. A mid-
or late-winter thaw can cause the plant to lose hardiness and
begin new growth which is injured or killed when the temperature
Temperature injury results in the browning or dieback
of newly-emerged shoots or buds. Flower buds may be killed
while there is no obvious injury to the rest of the plant.
To see if your tree or shrub was damaged, try to force the
flower buds in March or April. Cut branches and put them in
warm water in the sun. If the buds do not swell and open, they
were probably damaged during the winter.
Winter sunscald is a result of rapid changes in bark temperature.
During sunny winter days, the sunny side of the bark heats
up, then cools rapidly after sunset. Most sunscald happens
during January through March. Dark- or thin-barked trees, like
cherries, plums, peaches and crabapples, are the most susceptible.
Sunscald injury shows up on the southwest side of trunks, and
the bark may split or develop cankers.
Salt in the soil during active growth can make water and
essential nutrients difficult to absorb and predispose the
plant to other kinds of stress. However, salt is usually leached
out of the soil by spring rains and causes little damage unless
there is a winter thaw and roots come out of dormancy.
Salt spray is much more of a problem,
as the salt lands directly on the foliage of evergreens and
causes rapid water
loss or "burning."
Trees along roadside may develop a one-sided appearance
with the tips or margins of the leaves or needles looking burned
as a result of salt spray from snow plows landing on the leaves.
Conifers may develop shorter tufts of needles when active growth
Snow and ice accumulation on the plant can cause physical
damage as the plant is very brittle when frozen. A result may
be bent or broken stems or branches.
1. Use plants hardy to your area. Consult your nurseryman
as to the zone you are in. Drought-resistant or native plants
may suffer less winter damage.
2. Increase hardiness by slowing down growth. Do not fertilize
after July 4th.
3. Apply 3 to 4 inches of mulch when growth has hardened
(around the time deciduous trees lose their leaves). If the
plant was previously mulched, remove the mulch gently (to make
sure that the plant has not rooted out into the mulch) in October
to allow the roots to cool down and dry off somewhat. Replace
the mulch (3 to 4 inches only) when ground freezes.
4. Use an antidesiccant in late fall.
5. Provide windbreaks on the side of the prevailing winds
for plants in exposed sites. Lath, snow fencing or burlap may
6. Plant in sheltered locations, downwind side of less-sensitive
evergreens or courtyards. Avoid southern exposures. Move in
early spring or late fall when roots are dormant.
7. Plant at least 30 feet from sides of roads or provide
barriers/screens to decrease damage from salt spray.
8. Use salt-tolerant species.
9. Shade plants in mid-February through March to prevent
10. Use protective trunk wrappings on young or thin- or
dark-barked trees to prevent sunscald.
11. Keep plant healthy. Control insects. Make sure plant
receives adequate moisture throughout growing season, especially
during drought. In dry autumns, water the plant heavily before
the ground freezes. Never water when the ground is frozen.
Fertilize in spring.
12. Corrective pruning of broken branches or stems should
take place just before growth begins in the spring.
13. When snow or ice accumulates on plants, do not try
to remove it. Let the sun gradually melt the snow and ice.
The plant will recover slowly.
By Diana Vogel. Edited
by Kathleen Mallon and David B. Wallace.
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
of Rhode Island Cooperative Extension provides equal program