Tall Buttercup: The Notorious Pasture Invader

The bright yellow flowers of tall buttercup may look attractive, but this invasive perennial can reduce pasture productivity, crowd out valuable forage species, and pose a risk to livestock if consumed fresh.

Tall buttercup contains a compound called protoanemonin, which can cause irritation and blistering of the mouth, digestive tract, and skin if livestock consume fresh plants. Fortunately, livestock generally avoid grazing it when other forage is available, and the toxin breaks down as the plant dries, making it much less harmful in hay.

Its greatest impact is often on pasture health. Dense infestations compete with desirable forage species, reducing forage production and pasture carrying capacity. Once established, tall buttercup can spread rapidly and become difficult to manage.

Tall buttercup is listed as a noxious weed under Alberta's Weed Control Act. Landowners are required to control existing infestations and prevent the plant from spreading.

Identification and Habitat

Tall buttercup can be identified by its bright yellow flowers with five glossy petals. The upper surface of each petal has a waxy coating that gives the flowers a shiny appearance. The leaves are deeply divided into three to five lobes with coarse teeth. Leaf stalks are short or nearly absent near the base of the plant and become longer farther up the stem. Mature plants can grow 30 to 100 centimetres tall.

Several native buttercup species occur throughout Alberta and provide important ecological value. Unlike tall buttercup, these species generally do not form dense infestations in agricultural settings. When identifying tall buttercup, look for the combination of its shiny yellow flowers, deeply divided leaves, tall growth habit, and its presence in pastures, hayfields, and other disturbed areas. If you are unsure whether a buttercup is tall buttercup or a native species, proper identification should be completed before beginning control efforts.

Tall buttercup is most commonly found in moist pastures, hayfields, roadsides, and other disturbed areas. It prefers moist, fertile soils but can also establish in coarse or gravelly soils where sufficient moisture is available. During dry years, infestations may appear to decline, but established seedbanks allow populations to rebound when wetter growing conditions return.

Beyond agricultural impacts, tall buttercup can also threaten natural areas when it spreads into treed areas, wetlands, and riparian zones. Dense infestations can displace native vegetation, reducing plant diversity and altering habitat conditions for wildlife. Protecting these areas from establishment is important because once tall buttercup becomes established in sensitive habitats, control can be more challenging.

Prevention and Control

The best defence against tall buttercup is maintaining a healthy, competitive pasture. Rotational grazing, avoiding overgrazing, and maintaining a diverse stand of desirable forage species can help reduce opportunities for tall buttercup to establish.

Tall buttercup spreads by seed and through rhizomes, which are underground stems that allow the plant to produce new shoots and expand existing infestations. Preventing seed production, managing established plants, and avoiding the introduction of contaminated forage are key components of long-term management. Contaminated hay can introduce tall buttercup seed to new areas, so avoid purchasing or selling hay containing tall buttercup. Alberta's Certified Weed Free Forage Program helps producers source clean forage, and Rocky View County participates in this program.

Small infestations and infestations in sensitive areas may be managed by hand pulling or digging plants before they produce seed. Repeated monitoring and removal will likely be needed to prevent plants from becoming re-established. Wear gloves when handling fresh plants, as the sap can cause skin irritation.

For larger infestations, herbicides can be an effective management tool. ClearView, TruRange, Reclaim II, and Sightline A are available to agricultural producers and may provide residual control of tall buttercup and other broadleaf weeds. Par 3 and Trillion are available to acreage owners but do not provide residual control. Always select products registered for use on tall buttercup, follow all label directions, and confirm current product registrations before application. Herbicide timing is important, and applications should be made before plants produce seed.

Where infestations are severe, pasture renovation may be necessary. Tall buttercup does not persist well under cultivation, so tilling the affected area and establishing a competitive annual crop can help reduce existing plants. Because cultivation does not eliminate seed already present in the soil, continued monitoring and follow-up management are important. The area should be reseeded to perennial forage as soon as practical to restore a competitive plant community and reduce opportunities for other weeds to establish.

Dig Deeper

For more information on invasive species and native plants, please see the resources listed below.

Weed Identification

Certified Weed Free Forage Program

Native Species

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