Winter Burn of Evergreens
Mike Mickelbart, Horticulture & Landscape Architecture,
Janna Beckerman, Botany & Plant Pathology, Purdue
Winter burn is a common occurrence to boxwood,
holly, rhododendron, and most conifers. Winter burn symptoms often
develop when temperatures warm up in late winter and early spring.
This type of winter damage is often misdiagnosed as an infectious
disease or damage from excessively cold temperatures.
winter injury, it is important to understand that while a plant
is creating its food by photosynthesis, it is releasing large amounts
of water through the process of transpiration (the evaporation
of water from the plant). Over the course of a day, a large tree
can lose hundreds of gallons of water. When plants are unable to
obtain the water they need (due to drought or frozen soil), the
water lost through transpiration cannot be replenished, resulting
in dehydration, foliar damage, and even death.
The pines in the
picture are showing damage on the road side of the trees. This
is most likely a combination of three factors: 1) this is south-facing,
so heat from solar radiation will cause the needs on that side
of the tree to lose water more rapidly, 2) salt spray from the
road during winter can burn the foliage, and 3) increased wind
(relative to the north side) from traffic can lead to needles drying
Symptoms. Winter burn causes the scorching of
leaf tips or outer leaf margins, complete browning of needles or
browning from the needle tips downward, or death of terminal buds
and/ or twigs.
Management. Several techniques
to minimize or prevent winter burn can be implemented, with varying
degrees of success:
choose plant material, avoiding trees and shrubs that are known
to suffer from winter burn (including, but not limited to Sitka
spruce, English holly, and Colorado blue spruce).
planting broadleaved evergreens like rhododendron in areas of
high wind exposure.
- In the Fall, deeply water plants before the
ground freezes, and continue to water during winter months when
temperatures are above freezing but there is little precipitation
- Erect physical windbreaks
- Wrap problem plants
with burlap or other material to protect from wind and subsequent
moisture loss to evergreen shrubs and small trees.
of antitranspirants are available, but there is no data that these
products limit winter damage.
Click image to enlarge