For most of my career farmers have been reluctant to spray pastures for weed control using herbicides for fear of losing their legumes.  Even though in many cases the farmers overestimate the actual percentage of legumes in their pastures and would be ahead to spray hard to control weeds such as Tall Ironweed, cocklebur, etc.  In many cases the weeds make up 30-40% of the pasture.  Costing the farmer decreased carrying capacity and the loss of additional lbs of gain.  

This agent was approached by Dow Chemical Company two years ago about establishing on-farm trials to evaluate a new herbicide chemistry that may not kill legumes in pastures but control most all broadleaf weeds.  We are in the second year of a replicated study to evaluate this potential new chemistry.  Results look very promising after the first year of data.  If year Two looks as promising farmers will soon have a new herbicide on the market for controlling broadleaf weeds in pastures that could dramatically improve carring capacity of pastures and hay fields.