Control sericea lespedeza
By Todd D. Whitney
River Valley Extension District Extension Agent
Sericea lespedeza is a noxious weed spreading into area pastures. If the weather switches back to more normal rainfall patterns, then late summer or early fall will be a potentially good time to control the sericea. When the pasture grass plant leaves are browning, it is much easier to see sericea since these plants are still a clumpy, deep, green colored plant in infested pastures.
Sericea lespedeza (Lespedeza cuneata) or Chinese bush clover is an introduced perennial legume native to eastern Asia. It is a very tough plant tolerant of drought, acidity, and shallow soils of low fertility. Although it grows best on clay and loamy soils that are deep, fertile, and well drained, it also grows on poor sites.
The primary reason that sericea is a noxious weed in Kansas is that cattle do not like to graze on the growing plants. Unlike the southern states where sericea has a lower tannin content, sericea plants growing in Kansas extrude a bitter flavor. Thus, cattle do not actively graze on these weeds, providing a further advantage for these noxious weeds over the pasture grasses. (Conversely, if the plants are cut and harvested in a bale for forage, then the tannin content decreases and cattle will readily consume the forage. Yet, growing in a pasture, cattle will not consume these live actively growing weeds).
According to Walt Fick, K-State rangeland management specialist, when sericea plants are blooming in the fall, control products such as Escort and Cimarron Plus are often more effective as flowering ends and/or as seed pods appear and begin to fill. If treated at the full bloom stage and for a couple weeks afterward, recommended rates are 0.5 ounce per acre of Escort XP and 0.625 ounce per acre of Cimarron Plus. For spot, spraying, mix 1 fluid ounce PasturGare (Triclopyr + Fluroxypyr) per gallon of water; use a 1 percent solution of Remedy Ultra (Triclopyr) in water; or 0.3 grams Escort XP per gallon of water. Aerial applications of these products should be done with a minimum spray volume of 3 gallons per acre although higher rates (such as 5 gallons per acre) are usually more effective.
Sericea plants can be chemically killed until frost but if pod fill has begun, viable seed will still be produced. Grasslands with sericea lespedeza infestations should not be grazed or hayed after the sericea has gone to seed. This will only serve to spread the seed to other areas.
Our K-State River Valley Extension offices can provide free assistance with sericea plant identification. Also, more information on sericea control is available through the K-State website at: www.ksre.ksu.edu or any of our River Valley Extension District offices in Belleville (785-527-5084); Clay Center (785-632-5335); Concordia (785-243-8185) or Washington (785-325-2121).