THE ISSUE:  Perennial Pepperweed 

 Perennial pepperweed (Lepidium latifolium) is a native to southern Europe and western Asia. It was likely introduced into the U.S. as a contaminate in sugar beet seed. It invades meadows, roadsides, pastures, riparian areas, ditch banks, and other sites that remain moist most of the growing season.

Perennial pepperweed typically grows 1-3 feet tall, but it can grow much taller under optimal conditions. Growth originates from root crowns as a rosette, out of which flowering stems are produced. As the plant matures, roots and the base of stems become woody. It has bright green-gray lance shaped leaves that are larger at the base of the plant. Perennial pepperweed is known for having small clusters of white flowers. It has an incredible ability to produce seed! It can produce 6-16 billion seeds per acre. To make matters worse it can also reproduce from buds found on roots. Perennial pepperweed (also known as tall whitetop or broadleaf pepperweed) is a serious invader. 

Integrated Pest Management (IPM) Options: 

• Prevention— Learn to identify this plant. Never transport unknown plant material. Always plant clean seed! 

• Mechanical— Tillage can be effective on young seedlings but is not recommended for established plants. Its ability to reproduce from root buds allows it to spread and thicken when tillage occurs. Mowing in conjunction with herbicide applications can be an effective option. 

• Cultural— Use proper grazing techniques to encourage desirable plant growth, do not over graze.  

• Chemical— Chlorsulfuron and Metsulfuron are herbicide active ingredients that can be effective. Apply herbicides when weeds are actively growing. Getting good coverage of lower leaves tends to improve the efficacy of the application. Always read and follow herbicide label directions!

Justin Hatch, University of Idaho Extension Agriculture Educator in Caribou and Bear Lake Counties. 208-547-3205
[email protected]