Over the past few years, the level of buttercup prevalence in swards has been increasing steadily. Indeed, this year in particular, farmers have reported that buttercups are accounting, in some instances, for up to 40% of the ground cover. Amazingly, when observing these fields from a far, one would suspect that you are viewing a progressive crop of oilseed rape.

Buttercups are a perennial weed that is predominately found in swards. Following establishment, this weed has the potential to produce lots of seed and spread aggressively (along the ground by rooting runners).

Control of the weed is extremely taxing and difficult. This is mainly due to the fact that most buttercup plants emerge from seed during the harvest or late winter time-period. However, farmers generally do not recognise the issue or take corrective action until after the flower appears. At which stage (in the plant life cycle), the new seeds have already been produced and the implementation of control tactics is often too late. In reality, this is one of the principal reasons why buttercups survive from year to year, and new plants emerge annually.

As is the case with all weeds, their presence in swards replaces grass plants, suppresses growth, and competes for the limited nutrients available. The ultimate consequence of this is a dramatic reduction in grass yield. Where a dense buttercup population is present, farmers must ask the question and consider why has the weed invaded and established itself in these particular fields?

Characteristics and growing environment

Buttercups have a relatively low potential for poisoning livestock. However, all plant parts above the ground may contain toxins and the primary signs of toxicity are oral or gastrointestinal irritation. Typically, buttercups are not palatable and grazing animals rarely consume them if other forage is available.

If harvested in hay or silage, buttercups pose no threat, since the drying process eliminates the toxic agent and, in general, their presence in heavy crops would be quite low.

Buttercups flourish in wet soils and are typically seen in low areas of the field. Studies (from Purdue University) have shown the populations will readily germinate on the surface of exposed soil in open, poached and/or damaged swards.

Excessive overgrazing of poached swards, particularly during the late autumn and early spring months, was also highlighted as a leading cause of an increased population in fields. Therefore, the wet weather conditions that caused soil damage, poaching and compaction problems on many farms, along with a poor grass growth performance during the spring, are undoubtedly contributory factors to the current increased buttercup presence in Irish fields.

One of the best approaches in the controlling of buttercups is by inhibiting the growth of the weed, through outcompeting it with grass from a highly productive sward.

As a result, the principals that drive optimal grass production, such as excellent grassland management practices, proper soil fertility and pH status, and the avoidance of overgrazing, will all help limit the establishment of buttercups in grazing ground.

Controlling Buttercups

For fields heavily infested with buttercup, you may need to consider a variety of control strategies. For instance, apply a herbicide (step 1) to help reduce the population of buttercup plants in the spring, plus use good pasture management techniques (step 2) throughout the year to improve and thicken grazing swards.