Last year I planted a dwarf apple tree, and this year after returning from vacation it has a secondary tree that's sprouted up from around the base. Here's a photo showing what I mean:
A little hard to tell from the photo, but the secondary tree diverges from the main tree somewhere below the mulch/soil level. It went from nothing to what you see in the photo in the span of about 3 weeks.
Mainly I'm not sure if this is an issue, or what I should do about it if it is. Is it fine to just let the secondary tree do its thing, or is it better to take some action against it. And would that action be pruning it? Uprooting? Something else?