Description:
Perennial pepperweed normally grows 1 to 3 feet tall, but may reach up to 6 feet. The plant has many stems that emerge from a somewhat woody root crown. The alternate, waxy leaves may have smooth or toothed margins and a prominent, whitish midvein. Basal leaves are lance-shaped and up to 12 inches long; they are attached by a stalk that can be almost as long as the leaf blade. Stem leaves are smaller, with shorter stalks. The milky white flowers grow in dense, rounded clusters at branch tips. Each flower has 4 sepals and 4 petals. Fruits are small (1/16 inch), round or egg-shaped, and contain 2 reddish-brown seeds (Callihan and Miller 1998; Whitson 1987; Bureau of Land Management).

• Mechanical: Mechanical control of this plant is very difficult because very small sections of root contain buds that will sprout into new plants. Plant tops are easily killed, but root and crown buds can sprout and continue the infestation (Young et al. 1995; Young et al. 1998). Small infestations may be hand-pulled or dug, but as much of the root must be removed as possible. After control work, it is important to continue to monitor sites and remove all regrowth and seedlings.
• Biological: No biocontrol agents are available.
• Herbicide: Herbicides may be useful for controlling infestations. However, great care must be used, since many infestations occur close to open water. The plants are most susceptible to herbicides at the initiation of flowering (Young et al. 1997). 2,4-D amine, metsulfuron (Escort), and chlorsulfuron (Telar) all reportedly control perennial pepperweed. A surfactant is necessary with metsulfuron and chlorsulfuron (Beck 1996). Refer to the State Noxious Weed Control Board site

For More Information:
Detailed information about Perennial Pepperweed is available at the Washington State Noxious Weed Control Board Web Site.