The bark on the sunny side of my young tree is cracked, sunken, and peeling off

A patch of dead bark on the south or southwest face of a young, thin-barked tree, usually between the ground and the lowest branches. Early on it looks faintly sunken and off-color and sounds hollow when tapped; later the bark cracks at the edges and sheets off, leaving dry bare wood with a sharp raised callus rolling in from both sides. If a row of trees was planted together, the damage lands on the same face of every affected one — that repeating pattern is what separates it from a mower or animal wound. Newly planted maple, cherry, crabapple, linden, honeylocust, and young thin-barked oak are the usual patients.

Not urgent