The Clinic recently received an inquiry via our Ask an Expert feature, about the bark splitting on a red maple tree. A key piece of information was the south west exposure of the tree. The maple is suffering from what we call winter cracking or frost cracking in trees. What happens during very cold weather is that the side of the tree that faces south in the sunny location has temperature changes that are more pronounced than on the rest of the tree. The freezing and thawing of the bark and side of the tree facing that sunny area during the day, but re-freezing overall or at night, will lead to cracking of the bark. Many times the tree can heal or compensate for the crack in the bark on that side. You will want to watch that area closely for signs of insect damage or disease as time progresses, though. Do not paint or cover the area. The tree should begin to form a callus or thickened area around the split. Avoid fertilizing trees in the late fall, as that encourages new growth and new growth is more susceptible to splitting. Thin barked trees such as maple and cherry are more prone to frost cracking. Keep the tree watered next summer if we experience times of drought, and water once a week, deeply.
nfg 1/31/14
