Yes, the drone approach is very tempting. But I still insist on us removing the need to use of manmade chemicals that don't exist in nature naturally... (That I am aware of...)

For instance, I am all fine and dandy with using lye soap and vinegar to kill weeds. It's not 100% effective, but it's also not going to poison you just because your potatoes happen to be near by. Lye is a tricky example, because it's not exactly always natural, but not exactly always manmade either. You can get naturally occuring sources, etc.