[AKmark]

I am no great tomato grower, but have tinkered for quite a few years with different methods, and have formed a few opinions. I have never read a tomato book, just gathered tid bits along the way, so my fine print may be way off in actual fact.
In AK our summers are short, so I always let my indeterminates form two forks, or more, by letting a sucker form the growth extension. By doing this tomatoes set faster because of the extra trusses that are available within the forks. However in the world of heirlooms... every now and then I get a beast that grows, and grows, (plant matter), but has whole trusses of flowers break off. Now the reason for this is only my hypothesis, and I am open ears to professional interpretation, or correction in thought. Cal- mag wont stop it, even watering, nothing works, additives that is, bear with me here, and correct me if I'm certainly off base too.
With an OP in nature, there is always a tussle between root capability to deliver versus plants ability to take, an equilibrium between parts. In nature, when the equilibrium is broken, survival kicks in and flowers and fruit are the first to go in order to reset the balance for survival of the plants. As growers we want the plant part to produce flowers and fruit over plant matter, to an extent that is, at peak capacity in regards to root ability to provide.
In the case of my plant, for whatever reasons, GROWTH was stripping away the plants ability to set fruit because it was absorbing the root output at full capacity. I guess the good part of this can be that, these observations also allow growers to tailor strains, by selecting tolerate individuals for future endeavours.
Anyway; to remedy a current problem like this, simply cut the tops above the last trusses with flowers, and let suckers from lower on the plant become new tops. You should also take note how much pressure it takes to push nutrient way up through a tall plant, and with that said, there is a two pronged advantage to this method.