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Trees get sunburns too: tips to protect your trees from the sun this winter

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USU Forestry Extension
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Most Utahns are hoping for significant snowfall this winter so our lakes, reservoirs, and canals can be full of water next summer. Our way of life in these mountain valleys depends on winter snowfall, not only in the mountains, but in the valleys as well. Snowfall in the winter poses challenge for both fruit trees and shade trees. A little work now can prevent injury later.

As weather fronts come across the Intermountain West and deposit snow, it is common that the low pressure weather system that brought the snow will be followed by high pressure, accompanied by cold sunny days and clear, calm, cold night. 

During the day, light energy from the sun is reflected off the surface of the snow and the south facing bark of fruit trees and shade trees absorb this light energy. Because the bark is dark colored, it can warm up significantly, even during a cold, but sunny day. 

As the bark warms, it loses hardiness.  Clear sunny days are often followed by frigid cold nights and the bark that has lost its hardiness is damaged by the cold weather. This is commonly called southwest injury The injury is more likely on young trees than mature trees with corky bark.

This damage can be avoided in a couple of different ways. 

  • First, trunks can be wrapped with burlap, spun bonded fabric, or kraft paper. Rolls of these products are available from local garden centers or on-line sources. Wrap the trunks of young trees from the soil to a height of about 4 feet. Remove the wrap in the spring as the chance of snow wanes. 
  • Alternatively, tree trunks can be painted with dilute interior grade white paint. Mix 1 part paint to 2 parts water and brush onto the trunk, particularly the south and west facing portions with a brush. Don’t use colored paint or exterior grade paints. The white paint will reflect the light energy from the trunk and prevent it from warming on sunny days.

Either approach will protect tree trunks from damage.