The formation of a frost crack in a tree trunk can be alarming. Often a large cracking sound rings out as the crack forms. You will also notice deep vertical cracks running up the trunk, which may widen or close up in response to changing temperatures. Understanding the phenomenon can help you protect your landscape trees.
Frost cracks form on cold, clear winter days when temperatures are below freezing. The sun warms the south side of the trunk, heating it well above freezing, but then the sap inside expands too rapidly as it freezes back up after sunset.
Certain trees are more prone to frost cracking than others. Young trees have thinner bark than mature ones, which makes them more likely to experience cracking. Some species have naturally thin bark that cracks more easily. These include — but are not limited to — apples, beeches, willows, and walnut trees. Frost cracking tends to impact deciduous and broadleaf trees more than it does conifers, perhaps due to the harder wood and more exposed trunks.
The long, vertical cracks are open wounds on the trunk. Pests, fungi, and both bacterial and viral pathogens are more likely to make their way into the trunk due to the exposed heartwood. These problems can lead to tree decline and eventual death.
There are also structural concerns with frost-cracked trees. The more or deeper the cracks, the greater the concern. A crack can make the tree more likely to break in the event of high winds or stormy weather, simply because the trunk is not as strong as it would be if it were still whole.
Unfortunately, there are minimal treatment options once cracking has already occurred. Your tree service may clean up the wound if the surrounding bark edges are ragged, as a clean edge makes it more likely the tree will callus over the crack. The arborist may also stake the tree if there are especially deep or wide cracks that pose an immediate structural concern. This will give the tree some support as it heals over the wound.
The best treatment is prevention. If you have trees that could be prone to frost cracking, then have your tree service wrap the trunks before extreme winter temperatures arrive. Burlap wraps supply insulation to prevent the temperature fluctuations that lead to frost cracks.
Contact a tree service such as Carpenter Costin Tree and Landscape if you are concerned about frost cracks or other types of winter tree damage.