· Brent Wilson's Answer
· Hi Cheryl - As John mentioned, a picture of the bark splits would help for a positive identification, though sometimes it's difficult to determine exactly why the bark is splitting.
We usually see the bark splitting on young trees. These splits usually won't kill trees though, as John mentioned, they can allow diseases and insects in that could cause decay to set in.
As John also mentioned, there are many environmental factors that can cause bark to split on a plum tree.
Waether extremes can do it. Warm temperatures that come right after very cold weather can cause the bark to split. Also, a prolonged period of dry weather followed by a period with excessive moisture can cause the splits in the bark.
Over-fertilization can cause it, especially when fertilized too late in the season. Cease any fertilization two months prior to the typical first frost date in your area. Also avoid using quick-release, high-nitrogen fertilizers. Nitrogen is the first number in the three numbers found on fertilizers. I fertilize all my fruits and vegetables with a non-burning organic fertilizer.
Sunscald can also cause the bark on trunks or branches to split, especially on younger trees. The only way around this is to wrap the trunks of young trees with tree wrap. This product comes in rolls. It my be a "special order" item at your local nursery and garden center, though some may have it in stock.
Whatever the cause, you want to do something to help the wound heal. Tree paints and tars have shown very little if any value in helping to close wounds or help them to callus over. The best thing to do is to trace the bark around the split. To do this you'll use a sharp knife to trace around the wound about 1/2 to 1 inch beyond the split. When tracing just cut deep enough to go through the outer bark layer. Then, carefully remove the bark from inside the traced area. You should now have a bare area. Don't treat the bare area with anything...just leave it alone to heal naturally. If the tree is healthy, it shouldn't take to long for the bare to callus over completely.
Hope this info was helpful and let us know if you need more details or have any other questions.