Anybody had experience using a 4-wheeler mounted weed wiper to combat Smutgrass? I've got two pastures that have about been taken over. I'd say that 30-40% of those fields are Smutgrass. I need to deal with the problem this Spring. I really like the idea of the wiper. I'm scared to try the Valpar herbicide...don't want to kill my oak trees. I understand that can happen.