frost cracks[′frȯst ‚kraks]
cracks in the bark (and sometimes also wood) of the trunk and main branches of old trees with roughened, inelastic bark. They form during extended periods of very low temperatures when the outer layers of the bark and wood cool more rapidly and strongly than the inner layers. In the spring and summer callus (new tissue) forms along the edges of the crack and usually seals it. Frost cracks may lead to the appearance of hollows. Spraying the trunks and main branches with a lime solution (whitewashing) in the autumn helps to some extent in preventing the formation of frost cracks.