Species specifics: Annual broomweed

Fast facts

“Broomweed years” are years when annual broomweed grows so much that the canopies of the weeds become so thick that livestock can develop eye irritations – including pinkeye – while trying to access forages underneath
Native annual forb of the sunflower family that resembles a broom with a single woody stem and needle-like leaves feathered over a heavy canopy of branches at the top
Blooms bright yellow flowers in late summer to early fall
Commonly found in the southern Great Plains

What to look for

Annual broomweed (Amphiachyris dracunculoides), also known as common or prairie broomweed, is a native annual forb in the sunflower family found throughout the southern Great Plains.

Averaging 15 to 30 inches tall, the weed has a tough, woody stem that heavily branches near the top to form a crown – resembling an upside-down broom. Leaves on the branches are small, almost needlelike, and produce bright yellow flowers from August to November. Annual broomweed has a strong taproot that forms feeder roots close to the soil surface, allowing it to aggressively propagate in heavy rainfall years or in irrigated pastures.

Annual broomweed is a prolific seed producer that spreads by seeds dropped by the flowers. The plant can quickly germinate and grow into thick stands that can completely shade the ground, often leading to choking out favorable forages and native grasses. Some years of unusually heavy growth are referred to as “broomweed years,” when the broomweed canopies become so thick that, despite their best efforts, livestock cannot access grasses underneath, often leaving cattle with eye irritations that can develop into pinkeye.

Where it is found

Most commonly found in heavy clay soils, annual broomweed favors the climates of the central and southern Great Plains, including Kansas, Missouri, New Mexico, Oklahoma and Texas. However, it has been reported further east and southeast from its native ranges in states including Arkansas, Louisiana, Tennessee and Virginia.

How to treat it

Broomweed often requires multiple treatments depending on seasonal rainfall patterns, especially in “broomweed years.” Early detection of the plant and herbicide applications before blooming, while weeds are actively growing, are optimal.

Apply 16 to 20 fluid ounces of DuraCor® herbicide per acre or 24 to 33 fluid ounces per acreGrazonNext® HL herbicide. Use lower rates when weeds are small and actively growing and increase rates as the season progresses and the plants become more mature.

Under normal field conditions DuraCor® is non-volatile. DuraCor has no grazing or haying restrictions for any class of livestock, including lactating dairy cows, horses (including lactating mares) and meat animals prior to slaughter. Label precautions apply to forage treated with DuraCor to manure and urine from animals that have consumed treated forage. DuraCor is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. GrazonNext® HL has no grazing or haying restrictions for any class of livestock, including lactating dairy cows, horses (including lactating mares) and meat animals prior to slaughter. Label precautions apply to forage treated with GrazonNext HL and to manure and urine from animals that have consumed treated forage. Consult the label for full details. GrazonNext HL is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. GrazonNext HL is not for sale, distribution, or use in New York State and San Luis Valley of Colorado. Always read and follow label directions.