Every year I get lots of questions on why trees crack the most common reason is periods of severe cold, followed by rapid thawing, causes barks to split open. This is commonly referred to as frost cracks. Barks often split when trees are suddenly faced with ideal growth conditions following extended periods of slow growth. The sudden speed of growth causes barks to split under pressure. Sunscald during winter months is another possible cause of damage.Although bark splits are generally not fatal to the trees, they become entry points for numerous disease causing bacteria and fungi and cause the tree to be unattractive . The best way to aviod is to avoid creating conditions that are likely to cause bark splitting. Do not fertilize trees too late in the growing season as new, vigorous growth during winter is more prone to winter injury. Wrap trunks of new trees, especially, with tree wrap to prevent sunscald damage.