Broadleaved evergreens (boxwood, rhododendron, azalea, holly, etc.) and needled evergreens (yew, arborvitae, spruce, pine, etc.)
Description & Symptoms
Winterburn is a cultural condition that affects plants that do not lose their leaves over the winter. Leaves turn yellow and then brown in response to specific weather conditions. Leaves do not actually burn but rather dry up.
Timing & Life Cycle
Symptoms of winterburn typically appear first in late winter and accelerate in early spring. Various conditions combine to cause leaves to dry out. Mild winter temperatures and warm winter sun prompt leaves to process water, which cannot be replaced if the ground is either frozen or very dry. Winter winds also contribute to the problem. Winterburn is common after extremely cold and extremely mild winters, and in both cases it is exacerbated by lack of snow or rain in combination with strong winds and abundant sun.
Yellowing and browning leaves eventually die and will not green up, even under improved conditions. In severe cases, whole branches or sections of shrubs may defoliate.
Treatment & Solutions
Broadleaved evergreens should be planted where they will be protected from winter sun. Generally, an eastern exposure is best. In the fall, thoroughly water evergreens during dry weather until the ground freezes. Where practical, burlap screens can be constructed in the winter to provide some protection from wind and sun. In spring, wait until new growth appears before pruning out damaged areas. New growth may camouflage dead areas, making pruning unnecessary. In severe cases, plants may have to be replaced.
For more information about winterburn, call the Plant Information hotline at (847) 835-0972.