Question
Hello,
   My October's Glory Maple trees' bark split over the winter. Now I live in Fl. so the temp. never fell below 32 degrees for more than a few hours where I live, so I am wondering if it still could have split from the cold. My second part of my question is, that I was told by the my local home improvement store where I bought it (last year) that I should spray prune sealant (black tar?) in the split to protect the inside from disease and insects. I read that I should not do that after I had already done it? What should I do to fix it or should I leave it?

Answer
Sunscald is a  form of winter injury that can cause cracks and splits. Sunscald occurs when cells in the living tissue beneath the bark thaw out on sunny days. This occurs mainly on the south or west side of trunks and branches. These cells rupture when they re-freeze at night. The tree is injured when enough cells in a given area rupture. You'll notice the injury the following spring as a discolored, sunken area. Fungus infections often invade trees via sunscald injuries. Young, thin-barked trees are most susceptible to sunscald injury. These include maple, honey locust, linden, and mountain ash. Heavy pruning on neglected trees exposes sections of bark that have been protected from the sun's direct rays for years, predisposing them to sunscald injury.

You can reduce or eliminate sunscald injury on young trees by wrapping the trunks each fall with tree wrap paper. Do this every year until the bark begins to roughen. This may take only a few years on some trees, but more years on others. Prune trees that haven't been pruned for years in stages, not all at once. This will help prevent sunscald.

I would spray the area with an insecticide called Merit to prevent borers from entering the trunk. And fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. This will increase the health of the tree and allow the tree to better stave off any insect or fungi. The pruning sealant slows down the healing process. IT is not going to harm the tree but the wound from the scald will heal at a very slow rate . Trying to remove the product will cause more damage than just leaving it now.