hackberry split

[Bunyaneer]

This fissure recently appeared in my hackberry. It runs 2/3 the length of the tree, which is 2.5 stories tall. It's very near my house.
What to do? Remove it or treat somehow? How urgently should I act?
Thanks in advance for your help.

 

[Raintree]

Possible old lightning strike, less powerful bolts will travel down the inner bark without causing external damage. As the tree increases in diameter the old wound is revealed. If your Hackberry appears healthy I'd let it grow, it should close the wound over time. The surface seem is considered a structural defect that most likely will attract insects, just monitor it.