A few opportunities have come up for saving something with unknown availability for this gardener.
An annual brassica was one of these. I bought a package of seed off the rack in an Asian market, immediately forgotten was the name it was sold under. It isn't all that special but just a mild-flavored brassica. Buying seed for what I thought it is from 3 different seed companies has broadened my experience but hasn't eliminated the need to save seed from the un-duplicated original.
I found the annual brassicas easy choices for a casual seed-saver. My grandmother's tomato, from seed given me about 30 years ago, has been an easy save and not required isolation. Only once did it seem to cross with another variety. The experience made me aware of the value in saving seed from multiple years. No seed need be collected from the "suspect" plant(s). The "suspect" seed from the previous year can be tossed. And, older seed (not too much older!) can be used again. Worked!
Steve
Yes, thank you. I'm lucky enough to have two separate growing areas about 100 metres/320 ft from each other which for me, not selling seeds, is very helpful and not too far from the article's suggestion that 400ft is good enough for many purposes. It doesn't help with polytunnel or greenhouse crops but I can use it for sweetcorn, runner beans, various flower varieties, some alliums etc.You might find this interesting @Decoy1. It isn't a direct link to peppers and beans, but a deeper look at cross pollination in the industry. No wonder there is so much speculation about it, when some cross-polli info is considered proprietary. Interesting that we've had the same experience of seeing crosses in retail packets. The most memorable for me was a Marina di Chiogga squash, clearly crossed. I knew that OSC, the company I got it from, had isolation distances by the kilometer so I was surprised to see it.
Communing with Cosmos - EFAO
Starting in 2019, Kim Delaney conducted a farmer-led research project to see about reducing isolation distance for cut flower seed production.efao.ca
If you're persistent with your grinder you can go down a few inches so it would depend upon your effort. I think it would be better in the short term for shallow rooting crops and I don't know how quickly the remaining roots would decay.Can you plant a garden over an area that has had the stump base ground down? Or does the stump still remain fairly close to the surface?