Antagonism of glufosinate ammonium activity caused by glyphosate in the tank mixtures used for control of goosegrass (Eleusine indica Gaertn.)
T.S. ChuahA, H.H. TehB, T.S. ChaB and B.S. IsmailC
A Department of Agro-technology, Faculty of Agro-technology and Food Science, Universiti Malaysia Terengganu, 21030, Kuala Terengganu, Terengganu, Malaysia.
B Department of Biological Sciences, Faculty of Science and Technology, Universiti Malaysia Terengganu, 21030, Kuala Terengganu, Terengganu, Malaysia
C School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia.
Tank-mix combination experiments were conducted under glasshouse conditions to study the efficacy of tank mixtures of glyphosate plus glufosinate ammonium for the control of paraquat-resistant (R) and susceptible (S) biotypes of goosegrass at the young (3 to 4 leaves) and mature (2 to 4 tillers) stages. Fresh weight reduction for all mixtures of glyphosate and glufosinate ammonium were less (P <0.05) than the predicted value of fresh weight reduction, indicating strong antagonism between the two herbicides regardless of the growth stage. Although all tank mixtures of glyphosate plus glufosinate ammonium showed antagonistic reactions to each other with regard to their effect on the growth of goosegrass, these combinations still offered moderate to good control of both biotypes ranging from 68 to 89%. Comparison on the cost of application of tank mixtures revealed that the effective and economic rate of the herbicide combination treatment was a mixture of glyphosate at 75 g a.i. ha-1 with glufosinate ammonium at 25 g a.i. ha-1 at the 3 to 4-leaf stage. At the 2 to 4-tiller stage, it was found that 150 g a.i. ha-1 glyphosate plus 50 g a.i. ha-1 glufosinate ammonium was the most cost-effective combination compared to the other combinations. These tank mixtures reduced fresh weight of both biotypes by 86% at both growth stages.
Keywords: Joint action, goosegrass, antagonism, glyphosate, glufosinate ammonium.
Plant Protection Quarterly (2008) 23 (3) 116-119.