Frost Cracks and Sunscald on Young Maple Trees

Vertical bark splits on 6-year-old maples are likely frost cracks—caused by differential expansion of inner/outer wood during rapid winter temperature drops. Maples are highly susceptible. Sunscald on southwest sides is another winter injury.

Don't paint cracks. Remove loose bark. Wrap trunks with tree wrap paper each fall until bark roughens. Spray cracks with imidacloprid (Merit) to deter borers. Fertilize with 10-10-10 at 1 lb per inch of trunk diameter. Most cracks close in summer and reopen in winter but rarely kill the tree.