Buttercups mostly grow as winter annuals, although some species are classified as short-lived perennials. In Kentucky there are different species of buttercups that are known to impact pasture fields, such as hispid buttercup (Ranunculus hispidus), tall buttercup (Ranunculus acris), creeping buttercup (Ranunculus repens), bulbous buttercup (Ranunculus bulbosus) and small flower buttercup (Ranunculus arbortivus).  These plants typically produce five shiny, yellow petals beginning in the early spring.

Although different species may have somewhat similar flower heads (Figure 1), each of these buttercup species differs somewhat in their vegetative leaf characteristics. During the time petals are showy new seed has already begun to develop. Waiting until after flowers appear can be too late to implement control tactics. This is one reason buttercups survive year to year and new plants emerge each year.

Some buttercup plants may emerge in the fall but most plants emerge from seed during the late winter months when temperatures begin to warm. Buttercup is a cool season weed and often flourishes in over-grazed pasture fields with poor stands of desirable forages (Figure 1). Therefore, pasture management practices that improve and promote growth of desirable plants during these months are among the best methods to help compete against the emergence and growth of this plant. 

Conversely, livestock allowed to overgraze fields during the fall and winter months is one of the main factors that contributes to buttercup problems. Mowing fields or clipping plants close to the ground in the early spring before buttercup plants can produce flowers may help reduce the amount of new seed produced, but mowing alone will not totally eliminate seed production. 

For chemical control, herbicides registered for use on grazed grass pastures that contain 2,4-D alone will effectively control buttercup. Depending on other weeds present, herbicide products that contain dicamba+2,4-D (eg. Weedmaster, Brash, Rifle-D, etc.), aminopyralid (eg. GrazonNext, Duracor) or triclopyr (eg. Crossbow) can also be used. However, legumes such as clovers interseeded with grass pastures will be severely injured or killed by these other herbicide products. For optimum results, apply a herbicide in the early spring (March or early April) before flowers are observed, when buttercup plants are still small and actively growing in a vegetative growth stage. For best herbicide activity, wait until daytime air temperatures are greater than 60 F for two to three consecutive days. Consult the herbicide label for further information on grazing restrictions, precautions or other possible limitations. 

For fields heavily infested with buttercup, a variety of control tactics may be needed.  Apply an herbicide to help reduce the population of buttercup plants in the spring and use good pasture management techniques throughout the year to help improve and thicken the stand of desirable forages.

J. D. Green, PhD, is an extension weed scientist within UK’s Department of Plant and Soil Sciences in the Martin-Gatton College of Agriculture, Food and Environment.

Figure 1.  Hispid buttercup with mature flowers and new seed forming.

Figure 2.  Pasture field in late April with flowering buttercup.