When weeds invade pastures, it’s nearly always partly because the existing forage stand wasn’t thick or vigorous enough to out-compete them, says Bruce Anderson, University of Nebraska Extension forage specialist.
The first step in pasture weed control is to manage pastures so they can be competitive, says Anderson. “That may include fertilizing, extra seeding and especially well-managed grazing.”
Once weeds become a problem, though, control strategies must be used. One technique is to heavily stock a pasture, maybe with a 10-fold higher concentration of animals per acre than usual, for a very short time. You probably will need to use temporary cross fences to create small enough areas to achieve these high animal concentrations.
“If this is done while problem weeds are still young, many of them will be eaten readily,” he says. “Weeds like crabgrass, foxtail, field bindweed and lambsquarter make good forage when young. Animals even eat cheatgrass, downy brome and sandbur when plants are young. Once they form seed stalks, though, cattle almost totally reject them. Be sure to remove animals while desired grasses still have a few leaves remaining so they regrow quickly and compete with recovering or new weeds.”
Some established weeds aren’t controlled easily with grazing. Clipping or spraying them when their root reserves are low and to prevent seed production will reduce their pressure. “But remember, they will return quickly unless follow-up grazing management keeps your pasture healthy, vigorous and competitive,” says Anderson.