I was doing some electrical work at my in-laws this weekend and had to
relocate an electrical box. Unfortunately, they have plaster and lath wall
construction that quickly crumbled away as I was cutting the hole (it had
multiple cracks before I even started).

To get things fixed up as quickly as I could, I mounted the electrical box
and repaired the hole with the only supplies I had available at the time,
an old piece of 1/2" plywood. The switch box has a nice sturdy mounting and
it holds the wall together nicely.

Of course, the piece of plywood and the crumbled plaster edges don't look
all that great, so I'd like to patch it up a little to make it blend a
little better. The rest of the wall is in pretty rough shape already, and
we're planning on remodeling that room in a few years anyway. It doesn't
have to be top quality, but I don't want the patch to crumble away in a few
weeks either...

So, I'm curious if I can apply joint compound directly over the plywood
patch? I would use fiberglass mesh tape to control cracking, but will the
compound stick to the plywood? The plywood is very dry and has a rough
texture.

The overall patch is about 6" wide x 9" high.

Thanks,

Anthony