By Andi Anderson
Hemp dogbane and milkweed often grow together in fields, roadsides, and forest edges, and are commonly mistaken for each other. Both are toxic to livestock and spread rapidly by seeds and creeping roots.
Although similar in leaf pattern and milky sap, hemp dogbane has red-purple, thin stems and long, bean-like seed pods. Milkweed is hairier, with thick green stems and teardrop-shaped seed pods.
While both plants benefit pollinators and have cultural uses, they can reduce livestock health and forage quality. Toxic parts include fresh or dried leaves, stems, and roots. Symptoms range from vomiting to heart issues.
Horses are particularly sensitive. The risk increases when forage is limited or contaminated hay is mixed into feed.
Grazing systems pose lower risk as animals often avoid toxic plants. In hayfields, avoiding chopped rations and using long-stemmed hay can help animals sort out the plants. Do not force animals to consume entire bales if contamination is known.
Control methods include mowing and herbicide use. Mowing should be done early and often during the growing season to weaken root systems and prevent seed formation. Although mowing may reduce yields, it helps prevent further spread.
Systemic herbicides offer faster results. The best time to apply is when seedlings are under 8 inches or in early bud stage. Always use a surfactant to help herbicide absorb into leaves.
Effective herbicides for hemp dogbane include Remedy Ultra, 2,4-D, glyphosate, Cimmaron Max, and Curtail. For milkweed, glyphosate and Remedy Ultra are most effective.
While complete control may take multiple seasons, consistent effort using correct timing and products can significantly reduce plant populations, protecting both forage quality and animal health.
Photo Credit: istock-emholk
Categories: Ohio, Livestock