Hi Suz,

Split bark like what you have observed in your plum is a common winter injury among fruit trees and other trees with thin-skinned bark. It is often caused by a difference in thawing rates between the inner and outer bark layers, and can occur during a cold snap in the fall, before the tree has had a chance to harden off its bark for the winter.

If the tree is healthy, it may recover on its own over the summer by growing a callus over the crack. You can encourage this by fertilizing the tree in spring to encourage vigor and growth. Research has demonstrated that tree wounds also heal quicker when the extra bark is removed from the outer edge of the crack. To do this, use a sterilized knife blade to trace 1/2 to 1 inch around the split on the trunk, then peel away the bark inside the traced area.

Don't attempt to paint anything on the wound, as this will slow the healing process.

For more information about treating split tree bark, take a look at this publication from Cornell University: http://plantclinic.cornell.edu/factsheets/barksplitting.pdf

Good luck with your tree this summer!

Regards,

Sarah Bronstein

Master Gardener, '22