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Bumper Crop of Pasture Weeds Needs Action

Pigweed/Palmer Amaranth MU Photo

SEDALIA, Mo. – Leonardo da Vinci might have been describing the last few growing seasons for pastures when he wrote, “Even the richest soil, if left uncultivated, will produce the rankest weeds.”

University of Missouri Extension livestock specialist Gene Schmitz says the Renaissance polymath’s words ring true.

“The past one to two years have been hard on pasture stands,” Schmitz says. “Last summer’s drought followed by a wet winter and summer this year has led to a bumper crop of ragweed, foxtail and other pasture weeds. Trying to control weeds and rejuvenate pastures looks to be a major challenge in some areas.”

The first step is to assess what plants are growing in the pasture. If more than half of them are undesirable plants, consider complete renovation.

If renovation seems the best option and forage is in short supply during summer, adding native warm-season grasses allows for grazing and haying flexibility. It also provides important rest for cool-season forages, he says.

Start now for spring warm-season grass establishment. Test soil and fertilize accordingly. “Weed control is crucial in the establishment process of warm-season perennial forages and can begin this fall,” Schmitz says.

This option calls for spraying glyphosate in fall and then seeding a winter annual such as wheat, triticale or cereal rye. Promptly remove the winter annual crop in spring. Apply glyphosate again when winter annuals regrow after spring harvest, then seed native warm-season grasses. Monitor weed pressure in the new seeding and be prepared to control both broadleaf and grassy weeds.

Select the type of forage in a renovation program based on soil fertility, renovation and maintenance expense, and ability to manage different forage types efficiently.

These are not easy decisions, says Schmitz. Poor and weedy pastures may force some producers into hasty pasture-seeding decisions. When deciding what’s best for your pastures, plan and use current information such as soil fertility, desirable forage plant density and the need to fill forage voids throughout the year, he says.

For more information, contact Schmitz at or the MU Extension Center in Pettis County at 660-827-0591, or go to