Monsanto is offering an incentive for U.S. farmers who buy a dicamba-based herbicide. The incentive to use XtendiMax with VaporGrip could refund farmers over half the sticker price of the product in 2018 if they spray the herbicide on soybeans Monsanto engineered to resist the weed killer, according to Reuters. However, further restriction on dicamba-based herbicides are in place for …