The bean plants were dieing. Must be some dreaded plague infesting my garden which would spread to all 28 varieties, wiping them out and ruining my business. Not to mention all my friends would shun me and never share bean seed with me again. Life was over.
Turns out the beans in question were simply done. As in finished growing. Like, bean seeds were mature and dry so pick us already would ya! I feel like such an idiot.
So they are now picked and the pods are drying on the racks, the old plants have been composted, their area seeded with fall rye and life is good. Silly Trowel. You should have remembered that that variety was planted 2 weeks before the rest and would naturally be ahead. Wasn't rust, wasn't blight, wasn't anything, silly Trowel.