Weed of the Month: Buttercup
I’ve observed many area pastures dotted with the yellow-flowering buttercup over the past month–a sure sign of spring. Buttercup is toxic to all grazing animals, including horses, cattle and sheep. The plant contains a toxin called protanemonin, which is released when the fresh plant is chewed or otherwise wounded. Animals that eat buttercup may suffer from blistering of the mouth and lining of the gastrointestinal tract, diarrhea, colic, and, in severe cases, death. Fortunately, the unpalatability of the plant deters most animals from eating it if other desirable pasture plants are available. Buttercup toxicity is not a concern in hay since the toxin-containing plant oils evaporate quickly in drying forage.
Buttercup sprouts from seed in the fall or early winter, but is often only noticed later in the spring after the flowers bloom. Proper grazing and pasture management methods through the fall and winter that encourage desirable forage growth are preferred to help combat the emergence of this weed. If you’re currently seeing yellow flowers in your pasture, unfortunately the plant has already produced seed for the following year. Although mowing may help reduce further flower and seed production, mowing alone will not be enough to eliminate buttercup from your pasture.
Since some plants can return as perennials, and considering the toxicity potential, controlling buttercup with an appropriate herbicide (even this late in the season) may be the best option. For chemical control, herbicides registered for use on grass pastures that contain 2,4-D will effectively control buttercup. Depending on other weeds present or the emergence of new summer weeds (dog fennel, horse nettle and wing stem have all been spotted this week), other products containing multiple herbicides may be recommended. To determine the best plan for you and your pasture in Polk County, contact me at Cooperative Extension office.