Hello,

These bumps or nodules are called adventitious roots, prop roots, root initiatives, and sometimes root initials. This is the tomato plant's attempt to send out more roots. A tomato plant has the ability to send out roots from any where on the stem.  Some tomato varieties, especially heirlooms, are more prone to creating root initiatives than others. 

This is not a problem for the plant. There is nothing that you can do in this situation.  In the article below from Kansas State it mentions that waterlogged soil could possibly cause adventitious roots. With the heavy rains that have occurred recently, it may have encouraged the growth of the roots.

Whatever the reason, it's always important to maintain good watering practices when growing tomatoes.  Tomatoes like evenly moist soil and you should avoid overhead watering if possible to avoid fungal disease.  A layer of good quality mulch around the plants will help with moisture regulation during rainy and drought periods, and also help protect the plant from soil borne fungal spores.

For additional information, I've listed links below for articles on adventitious roots, and the proper care of tomatoes.

Please write back if you should have more questions.

Thanks for asking Ask Extension.

Betsy B. - MGV

https://extension.umd.edu/resource/bumps-or-swelling-vegetable-stems/

https://hnr.k-state.edu/extension/horticulture-resource-center/common-pest-problems/documents/Tomato%20Warty%20Stem.pdf

https://ohioline.osu.edu/factsheet/HYG-1624

https://u.osu.edu/growingfranklin/2019/06/18/keeping-tomatoes-healthy-in-wet-weather/