Tordon 22K doesn't kill grass. It only kills broadleafs when applied properly.

I've been using a helicopter outfit instead of a spray plane. It costs $4/acre more, but I've been getting almost 100% kills. They can put out over twice as much water per acre, and they use bigger droplets, so they get a lot better coverage.

You'd also be suprised at how much you can get done spot spraying. Since Surmount has been released, a 25 gallon tank only costs about $18 to mix. Tordon was costing about $27/tank to do the same thing. I've cleared several pastures of prickly pear by spot spraying.