Weeds can invade pastures when they are able to out-compete the existing forage stand. That means the first step in weed control is to manage pastures so the forage can be competitive. Techniques might include fertilizing, extra seeding and especially well-managed grazing, according to Chris Calkins, professor of meat science at the University of Nebraska.
If weeds are already present, control strategies must be used. One choice would be to heavily stock a pasture with maybe 10 times the concentration of animals per acre than usual for a very short time. This may require temporary electric cross-fences to create small areas to achieve these high animal concentrations.
If that technique is used while weeds are still young, many will be eaten readily. Some are good forage when they are young, such as crabgrass, foxtail, field bindweed and lamb’s-quarters. Even cheatgrass, downy brome and sandbur will be consumed when plants are young. But once these plants form seed stalks, cattle will reject them. It’s important to remove animals while desired forage still has some leaves remaining so they are able to re-grow quickly and compete with recovering or new weeds.
Not all established weeds can be controlled with grazing. Clipping or spraying these weeds when their root reserves are low will help prevent seed production and reduce their pressure. They can still return unless follow-up grazing management keeps your pasture forage grasses competitive.