Can you carefully raise the branch back up to stake it? If you leave it on the ground your tomatoes will be damaged from moisture on the ground. The other option would be to lift it enough to place a mesh 'table' underneath to support the branch while allowing for the water to pass through the mesh.
I am not a gardener, but the rocks seem to be allowing air to circulate under these so I would just watch them...could prove to be an very good learning experiment! You might want to elevate the limb by placing a larger rock, block of wood or something under the stalk at a couple of strategic places to get this lifted off the ground. If you are finding this to be a big problem on these plants, pick off some of the tomatoes before they get so big. And you can get old cloth strips and secure the limbs to a stake at more frequent than usual intervals, i.e., this bunch might need a tie at each end AND the middle. (I was raised with tending to a garden as a kid/teenager so I know that when tomatoes lie on the ground, rot is the big problem...so make sure they stay dry)
I like Four Season's idea of trying to prop the branch up enough to get a mesh hammock under the branch. Do whatever you can to tie up the branches on the rest of the plant.
'mortgage lifter's' are great !!
It looks like it may be too late to actual brace these plants sufficiently to prevent such events. However, I would look into stronger supports for next season and there are several ideals on Hometalk (i.e. building boxes to surround the plants, having your plants grow vertically on a trellis system).
If there is a semi-sturdier structure anywhere near the area (or you could devise one)..I've used old nylon knee-hi's to hammock my heavy maters. They tie off easy to anything available. They also stretch if they have to giving stems all the slack they need while still lending a 'staking' quality.
Thank you for these tips.. I will see what I can accomplish tomorrow :)
I was going to recommend stockings, but was not sure people had them in their vanities any more! HA! (Being retired, I avoid stockings) Actually, I cut up some old ones to use as ties last year! And I completely forgot about the slings I saw in the gardening books...that memory of mine is just so, so...But get them off the ground some way.
Thanks Jeanette!!! Stockings are not in my vocab any more... But in this case, yes I think stockings will work. Heading out that way shortly to do some rearranging :)