Location: Soil Dynamics ResearchTitle: Resurrection of glyphosate resistant palmer amaranth control in conservation tillage dicamba tolerant cotton; soil health salvation using herbicide technology
|DUCAR, JOYCE - Auburn University|
|STAPLETON, GREGORY - Basf Corporation North America|
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/5/2017
Publication Date: 7/5/2017
Citation: Price, A.J., Ducar, J.T., Stapleton, G. 2017. Resurrection of glyphosate resistant palmer amaranth control in conservation tillage dicamba tolerant cotton; soil health salvation using herbicide technology [abstract]. In: Weed Science Society of America Meeting Abstracts. CDROM.
Technical Abstract: Conservation agriculture hecterage in the mid-south and southeastern US has decreased because of herbicide resistant and other hard to control weeds. Producers have increasingly utilized tillage, the majority either using a moldboard plow to deeply bury weed seed and decrease emergence, or ‘vertical tillage’ to decrease surface residue in an effort to increase soil active herbicide placement and subsequent activity; soil health consequences be damned. However, high residue cover crops integrated with efficacious herbicide systems could protect yield, and preserve conservation agriculture practices and salvation for associated soil health indicators. In both experiments, cereal rye (Secale cereale L.) was established in half of the plots and managed for maximum biomass, while the remainder was managed herbicide fallow. In the glyphosate tolerant cotton experiment, for the first three years of the experiment, the factorial herbicide treatments included: 1) glyphosate applied at 1.12 kg ae/ha plus metolachlor applied at 1.12 kg ai/ha EPOST at cotton 2-leaf growth stage, 2) glyphosate applied at 1.12 kg ae/ha plus metolachlor applied at 1.12 kg ai/ha POST at cotton 8-leaf growth stage, or 3) flumioxazin 0.071 kg ai/ha applied as a PDS when cotton reached 45 cm height. In the glufosinate tolerant cotton experiment, for the first three years of the experiment, the factorial herbicide treatments were similar to the previously described, except glufosinate replaced glyphosate. In the fourth year, dicamba (applied at 0.56 kg ai/ha) replaced glyphosate or glufosinate in all treatments in each respective experiment. In 2013, in both experiments, early Palmer amaranth control exceeded 95% in rye and fallow systems following glyphosate or glufosinate EPOST. However by late season, glyphosate applied EPOST fb POST fb flumioxazin provided 83% in plots containing a rye cover crop, and control was substantially lower in all other treatments. In 2013 in the glufosinate experiment, sequential glufosinate applications EPOST fb POST or glufosinate applied EPOST followed by flumioxazin PDS when a rye cover was present, provided 99% late season control. However, in the winter fallow system, glufosinate EPOST fb POST fb flumioxazin PDS was needed to attain 99% control Palmer amaranth full season. Following decreasing Palmer control in 2014, in 2015 in the glyphosate experiment, no herbicide treatment provided >80% early control in cereal rye containing plots, and plots without three herbicide applications resulted in = 67% control in all plots. Control late season never exceeded 30% in the glyphosate experiment. In the glufosinate system, 95% or 93% late season control was attainable only in rye or fallow containing plots, respectively, when glufosinate was applied EPOST fb POST fb flumioxazin PDS. In 2016, Palmer amaranth control with dicamba was increased across all treatments following both glufosinate and glyphosate experiments, levels observed at the initiation of this experiment or higher late season.