Rehabilitation of perennial pepperweed infested habitats

Authors: Clements, Darin - Charlie; Harmon, Daniel - Dan

Submitted to: The Progressive Rancher
Publication Type: Popular Publication
Publication Acceptance Date: 1/17/2021
Publication Date: 2/7/2022
Citation: Clements, D.D., Harmon, D.N. 2022. Rehabilitation of perennial pepperweed infested habitats. The Progressive Rancher. 22(2):24-26.

Interpretive Summary:

Technical Abstract: Perennial pepperweed (Lepidium latifolium), also referred to as tall whitetop, is native to eastern Europe and Asia and was accidentally introduced into North America early in the 20th century. A member of the mustard family, this weed has spread to portions of all western states and adjacent Canada. In the Intermountain Area, perennial pepperweed first became established in riparian and wetland areas. It spread to native hay meadows and alfalfa (Medicago saliva) fields. Perennial pepperweed plants can produce large quantities of viable seeds that can reach 16 billion seeds/acre. The plants have an extensive creeping root system with the ability of very small fragments of these roots producing new plants. This makes mechanical control by tillage virtually impossible as following mechanical tillage can result in a significant increase in perennial pepperweed density and cover. The invasion of native hay meadows by perennial pepperweed is a threat to the range livestock industry of the Intermountain Area because these meadows are a critical portion of the forage base for both hay production and grazing of crop aftermath. We tested mechanical (discing), biological (goats) and chemical (herbicides), as well as a combination of these treatments to control perennial pepperweed infestations. Mechanical and grazing treatments did not reduced perennial pepperweed, whereas the herbicide application of 2,4-D in May following mechanical mowing significantly reduced perennial pepperweed and opened the opportunity to establish perennial grass that in turn effectively suppresses remaining perennial pepperweed and allows for the return of production agriculture back into these once peerennial pepperweed infested habitats.