Hello I was helping a friend weed and prune a garden and I noticed the bark on all 3 crabapple trees has splits in it mostly near the bases of the trees but one had a split further up the trunk. What could be causing this and what should be done to help the tree heal?
Onondaga County New York
The split in the trunk of your friend's crab apple trees is of some concern as it indicates a tree under stress but depending on the age of the trees and the depth of the split it may be of no harm to the trees. Bark splitting is not uncommon on thin barked trees like crab apples. Increasingly erratic weather patterns - alternating periods of extreme warmth and freeze in the winter and drought and flood in the growing season - are usually the reason. The bark and the tree's core are warming, chilling, drying and hydrating at different rates.
If the splitting is on the southwest facing section of the trees, it could be sun scald. This is the result of late afternoon sun hitting the bark of the tree, sometimes reflected off the snow, on cold winter days.
A young vigorous tree will repair itself from this sort of damage most times. An older tree may or may not.
You can help the trees by making sure that the cultural conditions in which they are growing are the best possible. Make sure there is nothing shiny nearby reflecting bright sun onto the bark. It would be helpful to make a soil analysis to see if there are any nutritional deficits that could be adding to the trees' stress. If you would like to do that on your own, you can get instructions on preparing a sample and expert analysis through your Onandaga County Cooperative Extension. The soil analysis will also tell you if your soil is within the right band of pH to make the nutrients in the soil available to a crab apple.
The cracks in the trunks may be an access point for insects or disease. Keep your eyes out for any unusual appearance of the leaves that may hold a warning for additional troubles. If you notice bug or disease activity in the cracks, it may be well worth consulting an arborist to assess the depth of injury to the trunk and any other factors evident on closer inspection and suggest a course of action.
Please let us know if we can be of further help.