Trees and shrubs are susceptible to damage from cold weather and harsh winter conditions. Low snow cover, animal damage and ice breakage can all damage tree bark and branches. However, damage from the sun shouldn’t be overlooked, even in the coldest winters. Sun scalding happens when the sun heats up tree bark, stimulating cambial activity. When the sun is hidden behind clouds or no longer heats up the tree bark, the active tissue dies.
To prevent sun scalding, wrap the trunk with a tree wrap, plastic tree guard, or light-colored material in the fall. The wrap will reflect the sun, keeping the bark at a steady temperature. Remove the wrap in the spring after the last frost.
Learn more at: http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/protecting-from-winter-damage/