At the bottom of my elm the bark has split. The tree is quite tall and about 30 years old. Can you give me advice?
Bark Has Split on Chinese Elm
If the bark has split clear down to the interior wood, then it needs to be sealed to keep insects out and prevent disease. There is a tar like product called Tree Wound Sealer on the market. Most garden centers have it. I believe ACE hardware carries it as well. Apply such a product to the split working it well into the split. Once done sprinkle it lightly with a fine sand to help make it less sticky, thus it will stay in place better if anything brushes against the treated area.