Ag Facts Radio Program - December
Monthly Radio Program on KUVR Radio.
I guess winter weather has returned to the area. Each spring I get phone calls about damage that winter weather has caused. Winter burn and winter drying are two common injuries to trees caused by weather. Winter burn refers to the browning of the needles on coniferous trees during the winter months. It is caused by rapid temperature changes, particularly on the south sides of trees where there is more exposure to the sun. Rapid temperature changes, which occur most often during sunset and sunrise, damage or kill needle tissues. Injured trees will usually recover if damage is not too severe as new growth from healthy buds cover damaged areas.
Winter drying damages both evergreens and deciduous trees. The actual damage occurs in late winter or early spring, but the symptoms may not show up until growth begins in the spring. Winter drying is caused by the desiccation of foliage and twigs by warm, dry winds, when water conduction is restricted by freezing of plan tissues or by frozen soil. All trees transpire, or lose, water, even during the winter months. Sometimes this loss is greater than the roots can replace and drying damage results. Minor damage results in reddening or browning of foliage, which may later recover. Symptoms of more severe injury includes browning and subsequent death of branch tips or entire branches. The side of the tree facing prevailing winds is most susceptible to winter drying.
Often, a combination of winter burn and winter drying will occur, occasionally complicated by drought. If damage is severe enough, affected branches may die. Sometimes, the entire tree may be killed.
Little can be done to control weather, but a few precautions can be taken to reduce the possibility of damage:
- Chose species which are hardy and best adapted to the area.
- Plant in well-drained, deep soils.
- Plant where trees may be protected form winds and sun.
- Water trees thoroughly in the fall and during the winter when water can be taken from the soil.
- Mulch around trees to prevent deep freezing.
- Maintain a fertile, well-aerated soil to encourage deep root growth.
- For additional information check out the Nebraska Forest Service Website at: http://www.nfs.unl.edu/adulteducation/forestrypublications.asp
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