It's challenging to diagnose diseases and disorders without pictures and a thorough history of what was done and when.

only a few diseases are soilborne. Most are transferred by air. Keys to success include healthy plants with good air circulation as well as fertilizer and water as appropriate.

Are you willing to try an antifungal spray like neem oil or daconil? The bulk bottles seem expensive but can make a lot of spray. The white powdery mold on the peas, cukes (melons and squash too?) should respond to the spray as a preventative, not a cure. Also is possibly a remedy for the toms.

Guessing a lot here without pics and climate info. Do you remember what the roots looked like when you pulled the tomatoes last time? Did the toms wilt, drop leaves, or just discolor? Did they all do it at once or at random over time? rain? sun? watering? All sorts of info needed to guess at a distance!

Anyhow, a good general idea is to not recycle any of these ill plants back into the garden soil, mulch, or compost.