Anyone have ideas what this could be? It’s the second one I’ve seen on our young 6+ft satsuma plum still on a pot. Zone 8a. The other one is also located near the base of the scaffold near the trunk. Nothing oozing out.
It appears similar to a failed T or Shield bud. I triedT budding on cherry, peaches, plum, and figs. The failed results always look similar to your pic. I have decided to never t- bud ever again as they take too long to heal and always seem to fail. My chip budding efforts have very good success ratios, so no more t- budding here.
As explained above, this looks like a callous area over small damage. However, if it grew to its current size, or it is growing, it may be some form of canker. In my experience, not all produce gum ( at least not all of the time ). I would keep an eye on it and, If it does appear to be growing larger, cut out that area of bark to clean, green wood.