Efficacy of tank-mixed bispyribac-sodium and surfactants against selected lowland and upland weeds and their safety to rice (Oryza sativa L.)
2019
Arcillas, L.S.N. | Bariwan, J.V. | Valencia, K.P. | Kumar, V.
A potential systematic post-emergence herbicide bispyribac-sodium (Bis-Na) was studied to determine its ability to control wide range of weeds and effect on rice. Addition of surfactants such as polyoxyethylene sorbitan fatty acids (PSFA) and terpene polymers (TP) was done to study their ability to increase the efficacy of the herbicide. During the 2017 wet season two sequential screenhouse trials were conducted at the International Rice Research Institute, Los Baños, Laguna, Philippines. The herbicide was admixed to the surfactants with 15, 20, 25 and 30 g ai/ha herbicide rate applied at 2-3 and 4-6 leaf stages. Weed control efficiency (WCE) and percent suppression were observed to determine differences in efficacy of control at the species level. Application of Bis-Na with PSFA at 2-3 leaf stage has the highest WCE of 75-100% in controlling grasses Echinochoa crus-galli (L.) Beauv. and Ischaemym rugosum Salisb. even at 15 g ai/ha. Meanwhile, application of Bis-Na alone was observed to be effective to sedges and broadleaf Ludwigia hyssopifolia (G. Don) Exell. The sedges Cyperus iria L. and Fimbristylis miliacea (L.) Vahl were effectively controlled by 20-30 g ai ha-1 and 15 g ai ha-1 herbicide rate, respectively. L. hyssopifolia was effective controlled by 15 g ai ha-1 upon application of herbicide at 2-3 leaf stage. On the other hand, application of Bis-Na with PSFA at 4-6 leaf stage of Eclipta prostrate (L.) L. has 100% WCE even at 15 g ai/ha. Based on the percent survival and percent tolerance, Bis-Na and surfactants have no significant effect on rice.
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