Perennial Pepperweed (Lepidium latifolium)

Perennial pepperweed or tall whitetop is a member of the Mustard farmily. It was introduced from either southern Europe or western Asia. It is a deep-rooted perennial plant with an extensive, vigorous creeping root system which reproduces by seeds and root stalks. Perennial pepperweed is similar to whitetop, however, it is taller. Perennial pepperweed stands 3 to 5 feet high with a heavy, sometimes woody, crown. The lower leaves are oblong with toothed margins. The upper leaves do not clasp the stem as whitetop. Flowers are white.

Perennial pepperweed can be found in pastures, riparian areas, roadsides, and waste places. It has a limited range in north and south central Colorado from 5,500 to 8,000 feet. In areas where the weed grows in Colorado, such as in the San Luis Valley along the South Platte Drainage, the plant has taken over thousands of acres.

Researchers from the ARS Exotic and Invasive Weeds Research Unit have recently published weed management advice in the Farmer-Stockman (July 2000) for this weed. First, spray the area with 2,4-D. Unlike many other pesticides the scientists tested, 2,4-D doesn't leave a residue in the soil that would prohibit using the land for growing crops like alfalfa.

Second, plant either tall wheatgrass or robust needlegrass, a competitive species under evaluation by ARS researchers in Logan, Utah. Both perennial grasses can out-compete tall whitetop if managed properly. A second year of limited 2,4-D application is necessary to help grasses establish. Land managers may have to graze the area to minimize stubble accumulation during the winter, because large amounts of stubble give rodents places to hide from the predators that normally prey on them. Large rodent populations will eat the grass seed, allowing tall whitetop to reinfest (Crummett).

Management Strategies | Back to Weed District