Screening herbicides and herbicide mixtures to identify alternative chemical controls for resistant plantago biotypes

Abstract

Herbicide mixtures are beneficial since they delay the occurrence of resistance to herbicides, provided that the herbicides used are effective at controlling the target weed species. Recently, plantago (Plantago lanceolata L.) was found to show 23 and 10-fold-resistance to glyphosate and paraquat. Experiments were carried out under controlled conditions to determine the efficacy of various herbicide concentrations and mixtures for the control of multiple resistant plantago at the two to three leaf stage. Proven plantago resistant (R) biotypes which had been shown to survive high glyphosate and paraquat dosages were used together with one susceptible (S) biotype in each experiment. The herbicides 2-methyl-4-chlorophenoxyacetic acid (MCPA), (400 g a.i. ha−1), carfentrazone-ethyl (400 g a.i. ha−1), and glufosinate (200 g a.i. ha−1), and two combined mixtures consisting of paraquat + diquat (120 + 80 g a.i. ha−1), and terbuthylazine + S-metolachlor (497.2 + 102.8 g a.i. ha−1) were applied either alone or in mixtures resulting in 12 treatments. The herbicides and combinations were chosen for their distinct modes of action. The mixtures achieved 0% survival rates for the R and S biotypes except for glyphosate + MCPA and MCPA applied alone. The herbicide mixtures identified in the study together with other non-chemical control options may be used in the management of glyphosate- and paraquat-resistant plantago infestations.