Field studies were conducted in 2001 and 2002 to determine the effect of clethodim, sethoxydim, and halosulfuron on centipedegrass seedhead suppression, seed yield, and seed germination. Clethodim (0.28 kg/ha), sethoxydim (0.31 kg/ha), and halosulfuron (0.06 kg/ha) applications were made at −2, 0, 2, 4, and 6 wk after mowing stopped (WAMS) in each year. Seedhead suppression varied in severity between 2001 and 2002, with increased suppression in 2001. Clethodim reduced seedhead emergence 50 and 33% when applied at 2 and 4 WAMS, respectively, in 2001. Sethoxydim reduced seedhead emergence by 21 and 18% when applied at 2 and 4 WAMS, respectively, in 2001. Halosulfuron had no effect on seedhead emergence in either year and did not reduce seed yield at any application timing. Clethodim reduced seed yield between 22 and 44% at all application timings. The pattern of yield reduction from sethoxydim was similar to that caused by clethodim; however, yield reduction with sethoxydim ranged between 7 and 48% for all application timings. The greatest reduction in seed yield occurred when clethodim and sethoxydim were applied 4 WAMS. Seed germination was not affected by halosulfuron or sethoxydim at any application timing. Clethodim, when applied at 4 and 6 WAMS, decreased seed germination by 17 and 20%, respectively.
Nomenclature: Clethodim; halosulfuron; sethoxydim; centipedegrass, Eremochloa ophiuroides (Munro) Hack. ‘Tifblair’ #3 ERLOP.
Additional index words: Seed germination.
Abbreviations: WAMS, weeks after mowing stopped; WAT, weeks after treatment.