Everything on the tree looks OK- metal (look at the screw indents) outside cover, used a junction box, attempt at strain relief. What strikes me is that the connector under the box looks like a plumbing PVC piece, and the conduit appears to be drip irrigation tubing. The curve in the tubing make me doubt that it's buried mor than a few inches deep.
Also: If he'd used a plastic outdoor box, he wouldn't need a ground wire.
