Recent rains across Kansas have caused sericea lespedeza to bloom in many areas. If your area is still dry and sericea is not actively blooming, it may be more effective to wait until next year to spray. The late-bud stage through the bloom stage is a good time to spray sericea lespedeza. Dense stands of this invasive, noxious weed need be addressed with broadcast or aerial applications of labeled herbicides to start reducing stands. However, scattered or sparse stands can be treated with spot-spraying.
Figure 1. Sericea lespedeza in bloom. Photo by Walt Fick, K-State Research and Extension.
Remedy Ultra (triclopyr) and PastureGard (triclopyr + fluroxypyr) can be effective during the early to full bloom stage, but products containing metsulfuron (such as Escort XP, Cimarron Plus, Chaparral etc.) are often more effective as flowering ends and seed pods appear and begin to fill.
Escort XP (metsulfuron) in the fall should be applied with a minimum of 3 gallons/acre spray solution. Add 0.25% non-ionic surfactant to 0.5 oz product of Escort XP. Chaparral (metsulfuron + aminopyralid) should be applied at 2.5 oz/acre beginning at flower bud initiation through the full bloom stage of growth. Aerial applications of Chaparral should be made with at least 2 gallons/acre spray solution. Dense or tall stands should be treated with 5 gallons/acre spray solution. Add 0.25-0.5% non-ionic surfactant when spraying Chaparral. Smooth brome and tall fescue may be suppressed or stunted by applications of Chaparral. Cimarron Plus (metsulfuron + chlorsulfuron) can be applied by air in a minimum of 3 gallons/acre spray solution at a rate of 0.625 oz/acre. Add 0.25% non-ionic surfactant and treat sericea lespedeza beginning at flower bud initiation through the full bloom stage of growth.
The same rates of Escort XP (0.5 oz/acre), Chaparral (2.5 oz/acre), and Cimarron Plus (0.625 oz/acre) as applied by air can be applied by ground applications using 10-20 gallon/acre spray solutions. Add a minimum of 0.25% non-ionic surfactant and treat sericea lespedeza through the full bloom growth stage.
Not all labels allow spot spraying. Always check labels for recommended rates and other precautions. For spot spraying, Escort XP can be applied at 1 gram/gallon of water or 1 oz/100 gallons of water. Add a non-ionic surfactant. Established stands of native grasses and smooth brome tolerate Escort XP, but tall fescue can be stunted.
Chaparral can be applied for sericea lespedeza control during the bud to flower stage at a rate of 2.5 oz/100 gallons of water. Add 0.25% non-ionic surfactant to the Chaparral application. As mentioned earlier, cool-season grasses such as smooth brome and tall fescue may be stunted by Chaparral. Spot spraying results in spraying to the point of wetting at about 40-50 gallons/acre.
Keep sericea lespedeza from going to seed
Sericea plants can be 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. If at all possible, keep sericea lespedeza from going to seed. Start planning now for follow-up treatment early next summer. Persistence is necessary to keep sericea lespedeza at reduced levels.
Walt Fick, Range and Pasture Management Specialist