Common Lespedeza (Kummerowia striata) Control within Maintained Centipedegrass (Eremochloa ophiuroides) Turf.

Common lespedeza or Japanese clover (Kummerowia striata syn. Lespedeza striata) is a warm-season, leguminous annual, which is native to Japan. It is a troublesome turfgrass weed within roadsides, home-lawns, and waste-areas of the Southeastern United States. Common lespedeza is similar in distribution to Korean Clover (K. stipulacea). However, each can be distinguished by close examination of differences in growth habit. Korean clover is often taller, producing coarse foliage with broader leaflets, and has upwardly pointing stem pubescence. On the contrary common lespedeza has retrorsely appressed (downward pointing) stem pubescence. Despite its prominence within many species of turfgrass, little research has focused upon herbicidal control of common lespedeza within centipedegrass (Eremochloa ophiuroides). Our objectives were to evaluate herbicidal control of common lespedeza and the resulting centipedegrass turf-injury.

Research was conducted at the Auburn University Turfgrass Research Unit, Auburn, AL. Studies were completely random by design and repeated four times in space and twice in time. Herbicides were applied to mixed centipedegrass-common lespedeza swards on August 4, 2010 and July 11, 2011 via a CO₂ pressurized back-pack sprayer at 280 L Ha^-1 utilizing Tee-Jet 8002 nozzles. Treatments included a non-treated control and eleven herbicide treatments: 2,4-D amine (15.8 g ae 100 m^-2), dicamba (11.2 g ae 100 m^-2), Trimec^® Southern (12.89 g ae 100 m^-2; a combination product of MCPA, 2,4-D, and dicamba), Escalade^™ 2 (16.82 g ae 100 m^-2; a combination product of 2,4-D, fluroxypyr, and dicamba), Celsius^™ (2.34 g ai 100 m^-2; a combination product of dicamba, thiencarbazone, and iodosulfuron), carfentrazone (0.34 g ai 100 m^-2), fluroxypyr (5.26 g ae 100 m^-2), chlorsulfuron (0.53 g ai 100 m^-2), two rates of aminocyclopyrachlor (0.79 and 1.05 g ai 100 m^-2), and atrazine plus bentazon (22.42 and 8.41 g ai 100 m^-2, respectively).  Common lespedeza control and centipedegrass injury were visually assessed relative to a non-treated check 1, 2, 4, and 6 weeks after treatment (WAT) in both years. Trifoliate leaf density was measured in 2011 and is presented as reduction relative to the non-treated. Basic normality assumptions were confirmed within SAS Procedure MIXED, and means were separated by Fisher’s LSD (α = 0.05).

Centipedegrass injury occurred more rapidly in week one of 2011 than 2010. This effect was presumably due to a period of high temperatures (> 32° C daytime) in the immediate days following 2011 application. Injury and common lespedeza control were similar between years for all assessment dates that followed; therefore, 2010 and 2011 ratings were analyzed as one. Centipedegrass injury was greatest due to both rates of aminocyclopyrachlor 4 WAT (> 40%). However, injury had subsided by 6 WAT. Centipedegrass injury was minimal (< 10%) due to all other herbicide treatments.

Visual assessments of common lespedeza control were similar between years at all assessment dates. We discuss 6 WAT assessments, as they are indicative of the long-term control expected from these herbicides. Escalade 2, fluroxypyr, and both rates of aminocyclopyrachlor controlled common lespedeza ≥ 99%, while chlorsulfuron, dicamba, and atrazine plus bentazon controlled common lespedeza between 60% and 75%. Trimec Southern, Celsius, carfentrazone, and 2,4-D failed to adequately control common lespedeza (≤ 31%). Trifoliate leaf observations confirm these results. That is, trifoliate leaf density was reduced to zero by Escalade 2, fluroxypyr, and both rates of aminocyclopyrachlor. Chlorsulfuron and dicamba reduced leaf density 60 and 70%, respectively, while 2,4-D reduced leaf density by only 30%.  Atrazine plus bentazon, carfentrazone, Celsius, and Trimec Southern did not statistically reduce trifoliate leaf density.

This study highlights several options for herbicidal control of common lespedeza. They include Escalade 2, shown by previous research to be a highly effective three-way mixture for control of various broadleaf turfgrass-weeds, as well as fluroxypyr (constituent of aforementioned Escalade 2), and aminocyclopyrachlor. These herbicides, and no doubt others, must be further evaluated for their function within maintained turf scenarios.