I am in zone 5 and just starting to see little green tomatoes. You don't say where you are located, but I wouldn't be worried about production yet.

The little white bumps look like adventitious roots, where the plant would grow roots if the vine were on the ground. I don't think they are affecting your production.

Steve

The bumps pop up when the humidity is high. Roots would sprout from those spots if they came into contact with the soil or you planted cuttings. Nothing to worry about.
Kim

Here is a link that might be useful: My Garden...including tomatoes

Oh cool!
I'm in New York and we have had some humid hot weather (I'm guessing that's the culprit)

If I were to chop that off, and plant the top of the plant, the mother plant wouldn't grow higher but would instead bush out, is that right?

"If I were to chop that off, and plant the top of the plant, the mother plant wouldn't grow higher but would instead bush out, is that right?"

That would depend on whether the parent plant is a determinate or indeterminate variety.

If it is indeterminate, the plant will continue to grow and one of the suckers or branches that you have now would become your main leader. The new plant from the cutting would grow the same as any normal indeterminate plant and will produce fruit.

If the plant is a determinate variety, it wouldn't be likely to grow anymore and depending on where the plant is in it's growth cycle it might not bush out either. (That is the reason it isn't recommended to prune determinate tomatoes.) Your new plant from the cutting may or may not make fruit since all the growth tips on a determinate variety are terminal tips, and they will stop growing when they have set fruit. If you take your cuttings before any fruit has set, you might get a decent plant and fruit from it.

Betsy