As weather warms...and it will - the calendar says it is officially spring - people will hopefully be spending an increasing amount of time outdoors. As they are outside, they may notice some things that they had not observed last year, and it may catch them by surprise, and they may begin seeking answers. We had just the situation in the OSU Lucas County Extension office when a resident stopped by to ask what happened to their tree over the winter.
Their verbal description of "vertical raised lines" on the main trunk of some of their trees in their landscape, and photos on their cell phone that they shared, confirmed what I suspected was frost cracks. Their visit to the office in search of answers to what they were seeing, planted the seed to do a BYGL Alert to describe what others might be seeing too.
If you too are seeing frost cracks, we would love to hear from you. You can email me at stone.91@osu.edu with a description or photos. Other information that could be helpful to include in the email: the location of the tree - county/city; the species of tree(s); the side of the tree that you are seeing the injury; and is this something new or is it reoccurring. Thanks, in advanced for sharing your observations if you are seeing frost cracks!
The photos that are included in this Alert were taking at the Toledo Botanical Garden (TBG) over a period of time this winter following a cold snap where temperatures dropped quickly and then warmed up. The frost cracks on these trees have been a reoccurring issue and something that I try to monitor when we are on the receiving of those very cold temperatures.
While the coldest days of the year might not have you running outside to check on your trees, it could be when you would see this injury in progress and the crack or cracks opened up as shown in the first three photos below. You will notice if you look closely there is callus tissue along the edges, indicating that there was earlier wounding and the trees natural response to that injury that happened. Once trees have developed a frost crack, it can reopen and close during other cold events in that same year, or in subsequent years.
This particular frost crack was wide enough that I was able to slide my hand into the opening. Image
The are certain trees that tend to be more prone to this happening, including young thin barked trees. Most commonly it is seen in sycamores, but has also been observed occurring on maples, apples, cherries, horse chestnuts, lindens, tulip trees, walnuts and willows.
The next two photos illustrate that sometimes when the wound closes, it leaves a raised ridge or bulge, rather than just closing flat. Image 1 and Image 2
Frost cracks are usually found on trees that are located in open areas where the sun shines directly onto the tree's trunk. The cracks typically begin on a winter’s day when the sun is out and the rising temperatures warm the bark and inner wood, usually on the south, west or southwest side of the tree. As the sun sets or is hidden on a cloudy afternoon, the temperatures can drop quickly. With a sudden and sharp temperature drop, the outer bark layer contracts more rapidly than the inner layers. The difference in contraction causes a spilt and can be particularly severe where there is a previous injury. Many have reported hearing a loud noise when the splitting occurs.
For additional information on this, several states have a FactSheets that you can refer to:
Missouri Botanical Garden:
Michigan State University:
https://www.canr.msu.edu/news/frost_cracks_in_trees
University of Connecticut:
https://homegarden.cahnr.uconn.edu/factsheets/frost-cracks-and-sunscald-on-trees/
Additionally, past BYGL Alerts that have also covered frost cracks include:
https://bygl.osu.edu/node/1246 (Cold Case Cracked: Crime on Crabapple Exposed (April 30, 2019), Jim Chatfield)
https://bygl.osu.edu/node/1917 (What's Cracking in the Yard of Woods (February 1, 2022), Carri Jagger)