Pretty Little Flowers But Definite Problem

DR. TERESA L. STECKLER

 SIMPSON, ILLINOIS

 Alright, many of you will say that this tidbit is a little late; however, better late than never!  Just in the last few weeks I have been receiving numerous calls about hairy buttercup.  Calls have ranged from how to rid my pasture/lot of this to do cows eat it.  There are many downsides (toxic to livestock, spreads aggressively, and is difficult to control) to this weed, but not is all lost.

 Many know hairy buttercup is a weed and has dark green stems with very bright yellow flowers with five petals. This weed is in the Ranunculaceae (buttercup) family which is native to the Canary Islands, North Africa, and Europe. This broadleaf is a winter annual that germinates in the fall or winter and remains dormant until spring.  Warm weather in winter can trigger growth. Buttercup thrives in disturbed areas particularly in moist ones and has dense fibrous roots. These plants can be problematic in no-till crops and pastures.

 While driving in Illinois, I saw many pastures with large stands of buttercup growing. Identifying buttercup is fairly easy when looking for the single yellow flowers with five petals. However, buttercup flowers can have a variable number of petals within the same species and some flowers can be white or pink, but most often bright to light yellow.  In some species the petals are waxy in appearance.  

 While a field of buttercup may be easy on the eye, they are problematic in pastures. All buttercups of the Ranunculus genus contain a toxic compound that is toxic to all species of livestock. The toxic component is an acrid volatile substance called anemoral and an irritant called protoanemonin. All buttercups have various amounts of these or related compounds. This compound produces an oily substance when the plant parts are crushed or eaten by grazing livestock. If consumed, animals that eat buttercup may suffer from blistering of the mouth and internal parts of the gastrointestinal tract, diarrhea, colic, and, in severe cases, death. Because of its bitter taste and toxic properties, cattle usually avoid consuming buttercup. However, large stands of buttercup may be difficult for livestock to avoid when the fields are covered each spring.

 Death of livestock due to buttercup is rare, especially if other forage is available. Grazing livestock will usually avoid buttercup because the leaves, flowers, and stems have a sharp, acrid taste. While many hay fields have some quantity of buttercup in them, the blistering agent is inactivated rapidly by drying, such that it is not generally a problem in hay.  Also, research indicates that the toxin is detoxified in baleage as well. 

 So what can one do to rid areas of this weed? New seed are produced during the time petals are showy. Waiting until after flowers appear can be too late to implement control tactics. This is one reason buttercups survive year to year. 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.

 In certain areas, grass/legumes are no longer growing and have become nothing but safe harbors for weeds. Thus, a great way to combat weed issues is to select well-adapted grass and/or legume species that will grow and establish rapidly. This will minimize the length of time for weeds to invade easily. A healthy stand of forage is a resilient stand. It is also important to test soils and lime and fertilize according to test recommendations. Maintaining a proper pH and nutrient status is essential in ensuring the forage will grow rapidly and be more competitive with weeds.

 However, sometimes chemical control is the most practical option. If so, do not wait until these plants are in full bloom. By the time these plants are in full bloom, you’ve missed the best window to halt seed production. In grass pastures several products (Cimarron Plus, Cimarron Max, and Crossbow) have excellent control of most buttercups you will encounter the products. Other products that have good control of buttercups are 2,4-D, Curtail, Milestone, and Forefront.  Dicamba may provide fair to good control but appears to be a little more variable than 2,4-D.

 Herbicides registered for use on grass pastures that contain 2,4-D will effectively control buttercup. For optimum results apply herbicide in the early spring (February – March) before flowers are observed and when buttercup plants are still small and actively growing. For best herbicide activity wait until daytime air temperatures are greater than 50 degrees for two or three consecutive days. Consult the herbicide label for further information on grazing restrictions, precautions, or other possible limitations.

 Although buttercups seem to be spreading in pastures and fields, several control methods exist. Also with less than average hay reserves, and increasing possibility of a drought, haying areas with hairy buttercup should not pose a problem to livestock. ∆