Once I figure out how to make it work at all, I'll build a network of plant nerds and teach them to do the same in their cities, and pivot to providing lab services and training for them. Much of the time no sequencing will be required, just a microscope and knowledge of what's growing nearby. But if they have more than one plant of the same species, sequencing will be necessary.

Fingers crossed they're not clones, though I suppose I could do lab testing for that as well, and then I maybe you'd have to kill multiple just to be sure you got the one. In that case, hopefully I'd have at least narrowed it down for you. Probably would just deny the job if the odd of being helpful are low, like if you have 50 clones of the same tree all growing along your sewer line, then I can't help you, it's time to start saving for a liner or a replacement.

It's like uber, but for shit-covered roots.

Now that I think about it - could you just pour some sort of biodegradable broad-spectrum herbicide down the drain to get the same effect for cheaper?

I don't wasn't to kill parents idea. It's neat, and Im sure there's use cases that my solution doesn't meet

It will not degrade anywhere near fast enough to not cause serious issues in the biological treatment stage of the wastewater plant.

https://www.naturemetrics.com/species-detection

https://www.ednacollab.org/industry/

https://wilderlab.co/

These companies focus on environmental DNA - some are more on the level of local government monitoring, some are for private customers.

Or in some cases you might not even need to kill the whole plant, just dig a targeted hole and hack off the problematic root. It'll probably take years for a different root to find the same crack in your sewer line and start wedging it open.