Best ultimate solution to the problem is to develop mass-producible (thus cheap) mini-robots, perhaps solar-powered, that roam fields and pluck out any plant other than the crop, while they are yet very small. Thus all agriculture will be organic.
Wow! What a great idea. Sure it can't be one extreme or the other, but robots could be an extension of the farmer's hands and other senses. Robots could monitor soil moisture, nutrient status, and even provide some watering services while they are also culling weeds. Some of that information might be available soon via satellite-mediated remote sensing of the farmer's fields, but maybe the two methods could be combined; with robots receiving commands from the satellite (or providing calibrating information for the satellite).
Robots in Agriculture! Of course! :headslap:
There are all sorts of possibilities that evolve from that singular idea. I think these qualify as synergized solutions, the best kind. I "second" Paul's post. Good going Warren!
p.s. ...and Thanks Mike! for the very neat article on evolving resistance.