– Victor Shelton, Retired NRCS Agronomist/Grazing Specialist
From a distance buttercup and cressleaf groundsel can appear similar.
This spring, I’ve received multiple inquiries about a yellow-flowered plant appearing in pastures and fields—seemingly more problematic than usual. That plant is buttercup (Ranunculus sp., not to be confused with Cressleaf Groundsel, Packera glabella; syn. Senecio glabellus), and while its bright yellow flowers might seem pretty to some, it’s definitely unwelcome in pastures and hay fields, especially if you’ve recently seeded hay fields or are trying to establish new forages.
Despite its seemingly sudden appearance, buttercup’s growth is due to a buildup of its seed bank, often accumulated over time. This buildup can happen through hay equipment contamination or, more commonly, from bringing in hay containing buttercup seeds and spreading manure from that hay. These seeds can lie dormant for years—typically 3 to 5, but sometimes longer—waiting for the right conditions. This is why buttercup seems to “suddenly” appear, even if it wasn’t noticeable in previous years.
Buttercup thrives when soil conditions are favorable, particularly after overgrazing or soil disturbance, which leaves bare spots where the seeds can establish without much competition. This spring’s wetter-than-usual conditions have exacerbated the problem, as buttercup flourishes in wet, compacted soils and bare ground—conditions that often follow overgrazing and limited pasture rest. The dry fall didn’t help either. If pastures are overgrazed or if livestock have had heavy foot traffic when the ground was soft, you’ve provided buttercup with the perfect environment to spread.
Competition is key to controlling buttercup. Healthy forage species must remain strong to outcompete it. If desirable plants are overgrazed or there’s bare ground, buttercup can take hold. Bare soil acts like a blank canvas for buttercup to grow quickly. The more competition from healthy, well-established forage, the less chance buttercup has to dominate.
Buttercup is toxic to all livestock species, especially horses. While most animals avoid it because they consider it undesirable, overgrazed pastures or a lack of desirable forage can force animals to consume it. If eaten, buttercup can cause mouth blisters, diarrhea, colic, or even death in severe cases. However, livestock typically avoid it when other options are available, especially horses, who tend to almost always graze around it. Cattle may graze it in desperate conditions, and sheep are more likely to consume it when it’s immature, though they can suffer from mouth blistering if they eat too much.
With this spring’s wet conditions, buttercup has gained an upper hand, especially in newly seeded fields or fields with a history of overgrazing. In newly seeded hay fields, buttercup seeds that were dormant in the soil now have the opportunity to flourish without sufficient competition.
Another concern is that buttercup is a high seed producer. A single plant can produce thousands of seeds, which can spread easily through wind, water, livestock, or equipment, quickly expanding the infestation.
So, what can be done about this yellow invader? Prevention is always the best approach. Ensure your hay is clean and free of buttercup seeds. Maintain good pasture management to minimize the establishment of buttercup seeds. Proper soil fertility promotes robust growth of desirable species that can outcompete buttercup. Regular soil tests and targeted fertilization help ensure your forage species are healthy and resilient against weeds like buttercup.
When herbicides are necessary, it’s important to note that there are few effective options for controlling buttercup in newly seeded fields, particularly those with legumes like alfalfa and clover. Many commonly used herbicides can damage young legumes during early growth. Once alfalfa and clover are well-established, herbicide options are still limited, with only a few available that won’t harm desirable plants.
Rotating grazing and providing adequate rest periods—at least 30 days—helps ensure desirable species remain competitive against buttercup and other weeds. Buttercup is especially prevalent when grazing is allowed to continue too long in the spring. Limit grazing periods to seven days or less.
Mowing after grazing helps reduce seed production. While buttercup can set seeds low to the ground, mowing right after grazing can reduce seed production and give your pasture a fighting chance. If the buttercup infestation is severe, herbicides may be necessary, especially when applied before flowering in early spring. However, be cautious, as herbicide application may affect other forage species, particularly legumes and forbs. Always consult with your local extension office or crop advisor to select the right herbicide. Fall applications can also help if combined with good grazing management.
While chemical control may offer short-term relief, long-term solutions focus on building a resilient pasture that can outcompete buttercup and other weeds. Ensure good soil fertility, promote diversity in your pasture mix, and utilize rotational grazing. Regular overseeding and maintenance of desirable forage species will keep the pasture thick and competitive.
As we move through this spring, take steps to protect your pastures from buttercup. Though it may seem like a simple weed, it can cause long-term damage if left unchecked. By acting now—through prevention, pasture and fertility management, or timely herbicide applications—you can protect your fields from long-term damage and ensure they remain healthy and productive.
Buttercup flowers
Cressleaf Grounsel flowers