I learned about this stuff tangenitally from The Big Lebowski because I had to look up what a “human paraquat” was the first time I saw it.
Unfortunately, I know about it because of a truly horrifying British PSA (“Apaches”) from before it was banned about the dangers of playing on a farm. Among other things, one of the children has a doll tea party and uses bottles and bowls for props. She meant to only pretend to drink from an unmarked brown clay bottle…
So what is a good weedkiller (herbacide) that isn’t harmful?
A goat.
I don’t think there are any
Very localized application to specific plants, ideally ones that are virtually impossible to mechanically remove and that threaten to smother local species.
An example would be Holly in the Pacific Northwest US, it spreads freely, outcompetes local species, and if you try to cut it down it spreads out underground like a hydra. Apart from getting machine digging to excavate the whole deep root, a measured amount of pesticide injected into the root crown is about the the only way to deal with it once it is established.
If this question refers to mechanized agriculture there are systems with cameras that recognize weeds in fields and specifically target them with a spray of poison.
If it’s a grass lawn, the best way is to internally adjust the image of a grass lawn from a golf course to a field at a school, church, or park near you where it’s mostly clover and dandelions. Then you don’t need to spray anything. Maybe then plant cool native plants and wow your friends with an impenetrable fortress of 10ft tall joe py weed filled with bees and butterflies but whatever you’ve got regionally.
If you can find it, ‘wood vinegar’ works as an herbicide at higher concentrations, but then supposedly dilutes throughout the soil/with rain to a level which is a type of soil amendment.
