Ok, well, so you do admit it that from engineering standpoint it is not too much of a challenge to do it. Now to the question of Why would they do it, way i understand it is they are spraying different chemicals which affects the natural gestation and grwth of the organic plant seed, whilst simultaneously there are government supported companies that are developing the genetically modified seeds that can survive the chemicals in the soil. If the spraying does not stop, farmers around the world might end up in a situation where they can not grow anything unless they spend millions of buying this genetically modified seeds. Now to add 2+2 and think where money from this will go, where else but on the very same military development.
That is not to mention that the chemicals make people sick, which again makes them to rely on drugs developing industries and so on and so forth..
Hardly a conspiracy really, as long as there are people going "I dont believe these conspiracy theories, I dont believe whats right in front of my face", the people responsible for this dont even have to hide...