I'm all for progress and improving farming practices and crop yields. Pesticides and herbicides and GM strains have done a lot not only to improve performance in farming "bread baskets" around the world but also to ease starvation in many hard-hit areas. My problem is that we don't know the long-term effects on humans for many of these chemicals and often these products are applied without following the manufacturer's guidelines (do you really think the Arg govt who is starved for soy Dollars is going to give the farming mafia here a hard time for aerial spraying over top of the farm worker's houses?).
My specific problem with Monsanto is that they are in bed with governments who are supposed to provide oversight. That relationship leads to all kinds of nasty offspring, not the least of which that they were able to get a patent on their GM seeds. Who gets a patent on a living organism? - the implications of that alone are scary. Not to mention that Monsanto is successfully litigating small farmers off of their lands in the US because those GM seeds blew across the road and took root in their fields. That's so #&%@ed up!