I should add that the "growth spurt" is mainly heavy foliage, probably due to high nitrogen in my soil (tilled in aged manure and mushroom compost last fall)

Mystery solved. My local garden center says that it is caused by watering the tomatoes too often, to let them dry out between waterings. Interesting that only one variety shows this symptom but I'm just happy that it is not a disease.

Any update, b/c spiral stems I don't know as a symptom of overwatering.Wilting and foliage turning yellow, but not spiral stems

Carolyn