What we discovered last year was that crowding tomatoes is a bad thing. Barb hates to waste seedlings, but spacing them 24” apart dramatically improved yield and allowed her to deal with diseases.
Just what we discovered.
Yep. Proper air circulation around your tomatoes, and pruning off all the unruly, unproductive ‘stuff’ helps greatly.
I have 4’ x 8’ beds, and I put 4 well-caged/staked plants in each. No disease issues until much later in the season...when I get lazy, LOL!