Wow I knew it was a problem but had no idea it was this bad. Must be spread by birds? I'd be pissed if my stuff got pollinated that way. I've been to the Emerald Triangle in areas where everyone was growing outdoors and things weren't that bad, but the people were cash cropping. During prohibition spreading cannabis plants around was fun and acceptable. Now that it's legal there's no excuse for that shit, especially hemp. If you're planting cannabis as an ornamental or for fun you should know enough to cull the males.
In India and other places with lots of cannabis plants, feral or wild and cultivated, this isn't really a problem. The different types of plants flower at different times. They may get a bit of feral hemp type pollen in their ganja flowers but most of it is male pollen from the ganja. A lot of the hempy wild stuff autoflowers or flowers long before the cultivated plants.
I would toss the mystery seed, not much of a reason to grow unlabeled stuff. Too many good strains available why waste your time when the males could be whatever. The volunteers, I'd cull most of them. I'd still take a look, do some stem rubbing and if something tickled my fancy I'd keep it. A few of your volunteers look like nice stuff, most of them look like whatever.
I've got volunteers this year but they aren't from careless neighbors they're from careless me. Last year I let my separated selected males go a bit further then I normally do, had a bit more seed in my stuff then normal. Still it was hardly any. October was wet, I had much more moldy buds then normal. Including purposely labeled seeds. After a while I stopped caring, didn't want to pick the seeds out of moldy goo when I had plenty of good seed already. I threw it on the ground in the garden.
This March we had a couple days above 70 degrees F. Much to my surprise I had 7 or 8 volunteers. Most of them were nice looking. In late April I was preparing my soil, I wasn't ready to transplant them and the guy who was manning my rototiller was going a bit fast and wild. I wanted to get it done so I transplanted 4 of the volunteers haphazardly. Not quite enough water and I threw them in regular old unprepared sandy soil.
They didn't die but they were stunted and burnt looking. A couple weeks later when I was planting out my purposely planted ganja I had to make a decision. I closed my eyes, cursed,and yanked the 4. It was especially hard to do because they were nice looking plants before I neglected them, I know the pollen came from select males. But I already had too many healthy starts I'd put out on purpose, didn't want any more runts and needed the space.
I kept the 4 I didn't transplant. I've got pics. Three popped up in one spot, I know this was a moldy seeded bud. I moved one to another spot, left a big one and a little one. The biggest one, the biggest volunteer all along, has a good skunky smell. It's the same size as my cultivated plants. Haven't done much for it until I dug fertilizer in around it a few days ago. Transplanted a bunch of potato plants away. You can see the little one on the left near the ground, it's much lighter green. I'm hoping the big one's female!
Here's the third one, it's always been scraggy. I'll probably leave it where it is until it sexes, let it go feral.
I gave it a bit of fertilizer, not a lot. They all came up near my potato patch, it's why I didn't move them. Didn't need to rototill there. The fourth one is in the potato patch. It's a bit scraggy as well. Probably leave it where it is, give it a bit of fertilzer, cull it if it's male. Let it grow together with the potatoes.
Behind it you can see a bit of my purposefully planted ganja patch. I wish I had pics of the other volunteers, they were superior to all but the big one. I wish I'd put them in containers earlier and taken better care of them, I'd like to have my own landrace.