Is there such a thing as an old canker? Is it possible that a canker that used to be active with for example bacteria, heals up, like on a trunk.
In my experience, an active canker is not going to heal without serious treatment e.g. copper ammonium or zinc oxidate.
Alright, if a tree was store bought let’s say and has a crevice in the trunk but there isn’t any gum would that mean a canker is healed, or if a specific spot happened on a tree and you didn’t notice it over a period of years, but when you notice it looks like a dry crevice.
More likely a sign of physical damage to the trunk, or where a branch was accidentally ripped off or purposely removed.