I’ve had some kind of illness with tomato plants and it spread in a way that is pathogenic where a 3rd plant was kept separate but upon leaving in closer proximity it become infected. I thought the first two were due to some circumstantial factors like using some soil from another plant that died, or pots with poor drainage, but the third plant did not have these factors. So am I forced to clean surfaces, toss the soil and start over, or can I reclaim the soil?
You probably don’t have to toss it. I’d try sterilization first, and if it happens again, you’ll know that the soil can’t be reused. You can sterilize it by baking it in the oven at 180°F for 30 minutes or leaving it in a clear plastic bag in the sun for a few weeks.