What is causing the rot-like damage on my apple tree?
Question:
My Ashmead’s Kernel apple didn’t do well last year. It looks like it didn’t overwinter well. I was doing some spring clean up and noticed some rot-like damage. Do you have any idea what is going on or how I can help?
Answer:
Tori Lee Jackson, Extension Professor of Agriculture and Natural Resources
It’s a bit tough to say from this photo, but it may be frost cracking. This can occur when the bark quickly changes temperature late in winter, usually on the south-facing side of the trunk. It can be prevented by wrapping the trunk in white plastic tree guard or painting the first few feet in white, interior latex paint each fall. This reflects light and prevents the huge temperature swings that leads to cracking. At this point, there is nothing you can do about the damage. Many trees can heal, but this can sometimes lead to a stunted or short-lived tree. The University of Connecticut has a nice article about sunscald and frost cracks.