While I was growing up I worked on my Grand Fathers farm. One of the most mundane task that needed to be done was spray for weeds. As he hated to use spray we did a lot of cultivating which was worse than spraying as it promoted land erosion.
There have been great advances in the science of growing crops and the farmer of today does not cultivate his corn or soybeans instead they use time proven methods to kill weeds but no matter how hard they try sometimes the mother nature throws a curve ball and the $10,000 worth of weed killer sprayed on in the morning is diluted by rain in the afternoon. With everyone trying to cut back on herbicides the perfect solution may have been found. Read this great story that I found on [Wired]