CHARLESTON, W.Va. -- Weather has been a hot topic around our area this year -- hot, hot summer; snowy fall; warm early December.
Certainly cold winter months are still ahead of us. Bert T. Swanson, a professor in the Department of Horticultural Science at the University of Minnesota, and Richard Rideout, city forester for the city of Milwaukee, are living in an area that is truly familiar with harsh temperatures. Recently they wrote an article about different ways the cold weather can damage our landscape plants. Over the next few weeks, I'll share some of their tips for saving your trees and shrubs from winter damage.
"Sun scald is characterized by elongated, sunken, dried or cracked areas of dead bark, usually on the south or southwest side of a tree. On cold winter days, the sun can heat up bark to the point where cambial activity is stimulated. When the sun is blocked by a cloud, hill or building, bark temperature drops rapidly, killing the active tissue.
"Young trees, newly planted trees and thin-barked trees (cherry, crabapple, honey locust, linden, maple, mountain ash, plum) are most susceptible to sun scald. Trees that have been pruned to raise the lower branches, or transplanted from a shady to a sunny location are also sensitive because the lower trunk is no longer shaded. Older trees are less subject to sun scald because the thicker bark can insulate dormant tissue from the sun's heat ensuring the tissue will remain dormant and cold hardy."
The specialists suggest wrapping the trunk of the tree with a commercial tree wrap, plastic tree guards or any other light-colored material, keeping the bark at a more constant temperature. Put the wrap on in the fall and remove after the last frost. Newly planted trees should be wrapped for two years, and thin-barked species up to five winters.
"Browning or bleaching of evergreen foliage during winter occurs for four reasons:
"1. Winter sun and wind cause excessive transpiration (foliage water loss) while the roots are in frozen soil and unable to replace lost water. This results in desiccation and browning of the plant tissue.