Answer: Let's start with some terminology! Frass is a polite word for debris or "poop" left behind by insects. It's not the same as a fungus. I looked up the earlier question you were referring to, and frass was given as a possibility.
Orange/yellow spots are often some type of rust, a fungal disease that can live to pop up when conditions are right--often warm weather and high humidity--which is exactly what happens during the monsoons. It's a great idea to harvest water from the rains, but if it is just splashing down uncontrolled into your garden, it may splash fungus from the soil up onto plant leaves, which is how many fungi spread. Rust is not a real common problem on vegetables, but corn rust can occur.
You were correct to destroy the infected plants and rotate crops every season. To kill pathogens in the soil, you need to solarize the soil--really heat it up for 2 months or so, by incorporating fresh manure, watering, and covering with plastic. It works best during the summer. If you have any of the infected plant material left, I suggest that you take it or mail it to the Cochise County Cooperative Extension so they can identify exactly what it is. 450 South Haskell, Willcox, 85643, 520-384-3594. Good luck!
Q&A Library Searching Tips