Sericea lespedeza is a non-native perennial legume that was introduced into the United States in 1896 as a forage crop. It resembles many other annual lespedezas utilized for forage but has erect stems that may reach as much as five feet in height (Figure 3). Sericea has trifoliate leaves with conspicuous points at the leaf tips. Individual leaves are rarely longer than one inch in length and have hairs on the leaf undersides only. Sericea plants are usually highly branched in the upper canopy and plants can occur as a single stem or as several stems that originate from the same perennial base. Sericea's flowers are not as noticeable as many other species but upon closer examination of these plants you will find white to yellow flowers with purple tinges located in the upper leaf axils of the stems (Figure 4).
In the early 1930's, sericea was often planted in Kansas and Missouri for erosion control, wildlife habitat, and occasionally for use as a forage. Over the last several decades, however, sericea has developed into a significant problem weed of pastures, hay fields, and roadside rights-of-way. It can tolerate a variety of soil conditions and competes with native vegetation for moisture, nutrients, and sunlight. It has the ability to emit chemicals that inhibit the germination and development of nearby plants (called allelopathy), and it is also a prolific seed producer (Figure 2). In 1970, some researchers found that established sericea plants could produce as much as 600 pounds of seed per acre annually.
Sericea can become a damaging invader in pastures, hay fields, and partially wooded sites. In these areas, grazing by cattle is limited to young, tender growth because these plants become unpalatable as the plants mature. For example, research has revealed that tannin levels increased from 6 to 21% as sericea increased from 4 to 36 inches in height. Because of this, cattle tend to selectively graze around the stiff stems during the latter part of the summer resulting in the production of additional seed for the following year.
Based on research conducted in tallgrass prairies of Oklahoma and Kansas, two strategies have historically been recommended for the control of sericea lespedeza with herbicides. First, good control has been achieved with applications of triclopyr or triclopyr-containing herbicides when applied to vegetative sericea in June or July. Triclopyr is the active ingredient in Remedy and is also one of the components of Crossbow and PastureGard. Second, good control also has been observed with applications of metsulfuron or metsulfuron-containing herbicides when applied to sericea lespedeza at early bud to bloom growth stages, which typically occurs in August or September. Metsulfuron is the active ingredient in Cimarron and Escort, and is also included with 2, 4-D and dicamba in a prepackaged herbicide mix sold as Cimarron Max.
In research we have conducted in Missouri, however, we have not observed a difference in the level of Sericea lespedeza control between herbicides that were applied in the vegetative stage versus the early bud to bloom stage. In other words, in our research PastureGard at 2 pints per acre provided as effective control of Sericea when applied in the vegetative stage as in the early bud to bloom stage. It is likely that the annual rainfall patterns in Missouri are much different than those experienced in the tallgrass prairies of Oklahoma and Kansas where this previous research was conducted, which may account for some of the differences in the results from these experiments.
For more information on Sericea lespedeza and other species, visit the MU Weed Identification Guide Web site at http://weedid.missouri.edu.
REVISED: October 2, 2015