Answer: Frosty weather can cause cracks in the bark of an avocado tree, as can sunscald when winter sun shines on cold bark. Or, there's a disease that affects avocado trees called black streak. The bark develops cankers and then oozes black sap. Let's hope this is not what is causing the splits on the bark of your tree - it's a serious disease. I would just leave the tree alone and see if it attempts to heal over the cracks in the bark. Hope so!
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