Efficacy of tank-mix combinations of glyphosate and gramicides on the control of glyphosate resistant and susceptible biotypes of goosegrass (Eleusine indica (L.) Gaertn.)
T.S. ChuahA, S. SalmijahB and B.S. IsmailB
A Faculty of Agrotechnology and Food Science, Kolej Universiti Sains dan Teknologi Malaysia, Mengabang, Telipot, 21030 Kuala Terengganu, Terengganu, Malaysia.
B School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia.
Greenhouse studies were conducted to evaluate the efficacy of glyphosate alone or tank-mixed with sethoxydim or fluazifop-butyl on glyphosate resistant (R) and susceptible (S) biotypes of Eleusine indica (L.) Gaertn. at two growth stages. The R-biotype was more effectively controlled when young (3-4 leaves) rather than when mature (3-4 tillers). Young plants of the R-biotype can be controlled (>95% control) by glyphosate at high rates of 2.88 and 5.76 kg a.i. ha-1 four weeks after treatment (WAT). However, when mature, the R-biotype was not controlled (<50%) by glyphosate even at 5.76 kg a.i. ha-1. Sethoxydim at 0.60 kg a.i. ha-1, all tank-mix combinations of sethoxydim or fluazifop-butyl and glyphosate provided good control (>95%) of young R-biotype plants. However, mature R-biotype plants were only controlled by sethoxydim at 0.60 kg a.i. ha-1 (78%) or combinations of high sethoxydim and low glyphosate rates (82-92%) at 4 WAT. Although most of glyphosate combinations with sethoxydim acted antagonistically, the control of the R-biotype provided by the tank mixtures was greater than the control provided by glyphosate applied alone at the mature stage.
The S-biotype was controlled (78-99%) with glyphosate at 1.44 kg a.i. ha-1, sethoxydim at 0.60 kg a.i. ha-1 and all tank-mix combinations of sethoxydim or fluazifop-butyl and glyphosate at the young and mature stages 4 WAT.
Plant Protection Quarterly (2004) 19 (4) 130-134.