Abstract
The evolution of glyphosate and acetolactate synthase (ALS) inhibitor-resistant common waterhemp in the Midwestern United States has reduced the number of effective POST herbicide options for management of this problem weed in glyphosate-resistant soybean. Moreover, common waterhemp emerges throughout the crop growing season, justifying the need to evaluate herbicide programs that provide season-long control. The objectives of this study were to compare POST-only and PRE followed by (fb) POST herbicide programs for control of glyphosate-resistant common waterhemp in glyphosate-resistant soybean. Field experiments were conducted in 2013 and 2014 in Dodge County, NE, in a field infested with glyphosate-resistant common waterhemp. Programs containing PRE herbicides resulted in ≥83% control of common waterhemp and densities of ≤35 plantsm-2 at 21 d after PRE (DAPRE). Post-only herbicide programs resulted in <70% control and densities of 107 to 215 plants m-2 at 14 d after early-POST (DAEPOST) treatment. PRE fb POST herbicide programs, including saflufenacil plus imazethapyr plus dimethenamid-P, sulfentrazone plus cloransulam, or S-metolachlor plus metribuzin, fb fomesafen plus glyphosate; S-metolachlor plus fomesafen fb acifluorfen plus glyphosate resulted in >90% control of glyphosate-resistant common waterhemp throughout the growing season, reduced density to ≤7plantsm-2, ≥92% biomass reduction, and soybean yield >2,200kg ha-1. Averaged across herbicide programs, common waterhemp control was 84%, and density was 15 plants m-2 with PRE fb POST herbicide programs compared with 42% control, and density of 101 plants m-2 with POST-only herbicide programs at harvest. Results of this study indicated that PRE fb POST herbicide programs with effective modes of action exist for season-long control of glyphosate-resistant common waterhemp in glyphosate-resistant soybean. Nomenclature: Acetochlor; acifluorfen; chlorimuron-ethyl; cloransulam-methyl; dimethenamid-P; flumioxazin; fomesafen; glyphosate; imazethapyr; lactofen; saflufenacil; S-metolachlor; sulfentrazone; thifensulfuron-methyl; common waterhemp, Amaranthus rudis Sauer; soybean, Glycine max (L.) Merr.
Original language | English (US) |
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Pages (from-to) | 53-66 |
Number of pages | 14 |
Journal | Weed Technology |
Volume | 31 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1 2017 |
All Science Journal Classification (ASJC) codes
- Agronomy and Crop Science
- Plant Science