Downy brome is one of the most troublesome weeds in no-till wheat production systems of the US Great Plains. Pyroxasulfone is a relatively new, soil-applied residual herbicide (root/shoot growth inhibitor) labeled for...Downy brome is one of the most troublesome weeds in no-till wheat production systems of the US Great Plains. Pyroxasulfone is a relatively new, soil-applied residual herbicide (root/shoot growth inhibitor) labeled for use in wheat. Multiple field experiments were conducted near Huntley, MT from 2012 through 2016 to determine the efficacy of pyroxasulfone to control downy brome in imidazolinone (IMI)-tolerant (Clearfield™) winter wheat. Pyroxasulfone did not cause any injury to wheat in any of the three studies. Downy brome injury with pyroxasulfone preemergence (PRE) only program did not differ between 89 or 178 g·ai (active ingredient)·ha-1 rates, and averaged 82% and 84% in 2 separate studies. In a preplant (PP) burndown program, the addition of pyroxasulfone (178 g·ai·ha-1) to glyphosate improved downy brome end-season injury from 15% to 74%. In a separate study, the end-season injury with pyroxasulfone was greater when applied PRE (84%) compared to the delayed PRE (DPRE) timing (74%). In addition, the water dispersible granule (WDG) formulation of pyroxasulfone performed slightly better than the suspension concentrate (SC) formulation for downy brome injury. Pyroxasulfone applied PRE in the fall at a rate of 89 g·ai·ha-1 followed by (fb) imazamox (44 g·ai·ha-1 rate) applied postemergence (POST) in the spring effectively controlled downy brome (99% end-season injury). Furthermore, the injury was consistent with the standard program comprising of propoxycarbazone (29 g·ai·ha-1) PRE fb imazamox POST in IMI-tolerant winter wheat. In conclusion, pyroxasulfone applied PRE in the fall can be effectively utilized in conjunction with a standard acetolactate synthase (ALS)-inhibitor-based POST herbicide program for a season-long downy brome management in winter wheat.展开更多
A field study was conducted at two locations in Kansas, USA in 2011 and 2012 to test weed control efficacy and crop response to preemergence-applied pyroxasulfone alone and in combination with sulfentrazone in sunflow...A field study was conducted at two locations in Kansas, USA in 2011 and 2012 to test weed control efficacy and crop response to preemergence-applied pyroxasulfone alone and in combination with sulfentrazone in sunflower. Treatments included three rates of pyroxasulfone (100, 200 and 400 g·ha-1) applied alone and tank-mixed with sulfentrazone at 70, 140 and 280 g·ha-1. Commercial standards sulfentrazone at 140 g·ha-1 + pendimethalin at 1390 g·ha-1 and sulfentrazone at 140 g·ha-1 + S-metolachlor at 1280 g·ha-1 were also included. Pyroxasulfone at 100 g·ha-1 controlled Palmer amaranth 87% at 3 weeks after application (WAA), but control decreased to 76% at 6 WAA. Increasing pyroxasulfone rate to ≥200 g·ha-1 or tank mixing with sulfentazone at 140 g·ha-1 provided ≥90% Palmer amaranth control for at least 6 WAA. Sulfentrazone alone at 70 g·ha-1 controlled Palmer amaranth 77% at 3 WAA, but control dropped to 69% at 6 WAA. Increasing sulfentrazone rate from 70 to 140 or 280 g·ha-1 increased control to >90% at 3 WAA, but did not maintain acceptable control at 6 WAA. Tank mixing sulfentrazone at 140 g·ha-1 with pendimethalin at 1390 g·ha-1 or S-metolachlor at 1280 g·ha-1 controlled Palmer amaranth ≥90 and 84% at 3 WAA and 6 WAA, respectively. The lowest rate of pyroxasulfone (100 g·ha-1) controlled kochia 98% and the control was complete with all other treatments. However, no treatment provided as much as 90% puncturevine control at 3 WAA and the control was commercially unacceptable (<75%) at 6 WAA. No treatment visibly injured sunflower anytime during the season or reduced sunflower plant population.展开更多
Emergence of grasses late in the season has become a problem in glyphosate-resistant (GR) soybean production in the southern US. A 3-yr field study was conducted from 2011 to 2013 at Stoneville, MS to determine effica...Emergence of grasses late in the season has become a problem in glyphosate-resistant (GR) soybean production in the southern US. A 3-yr field study was conducted from 2011 to 2013 at Stoneville, MS to determine efficacy of post-harvest and pyroxasulfone-based in-crop herbicides on late-season grasses and yield in twin-row glyphosate-resistant soybean. Experiments were conducted in a split-plot arrangement of treatments in a randomized complete block design with fall herbicides (with and without pendimethalin at 1.12 kg ai ha-1 and paraquatat 0.84 kg ai ha-1) as main plots and in-crop herbicides as subplots with four replications. The six in-crop herbicide programs were: glyphosate applied early postemergence (EPOST) at 0.84 kg·aeha-1 followed by (fb) glyphosate late postemergence (LPOST) at 0.84 kg·ha-1 with and without pyroxasulfone preemergence (PRE) applied at 0.18 kg ai ha-1, pyroxasulfone PRE fb glyphosate at 0.84 kg·ha-1 LPOST or glyphosate at 0.84 kg·ha-1 + S-metolachlor at 1.68 kg ai ha-1 EPOST, pyroxasulfone PRE fb S-meto- lachlor at 1.12 kg·ha-1 + fomesafen at 0.27 kg ai ha-1 EPOST fb clethodim at 0.14 kg ai ha-1, and a no-herbicide control. Browntop millet, Digitaria spp., and junglerice densities at 2 weeks after LPOST, grass weed dry biomass at harvest, and soybean yield were similar regardless of post- harvest herbicides in all three years. At 2 weeks after LPOST, browntop millet, Digitaria spp. and junglerice densities were greatly reduced in all five in-crop herbicide treatments compared with no herbicide plot in all three years. Grass weed dry biomass in no-herbicide plots was 3346, 6136, and 6916 kg·ha-1 in 2011, 2012, and 2013, respectively and the five herbicide treatments reduced grass weed dry biomass by at least 87%, 84%, and 99% in 2011, 2012, and 2013, respectively. Soybean yield was higher with all five in-crop herbicide treatments compared to no herbicide control in all three years. These results indicate that browntop millet, Digitaria spp., and junglerice infestations can be reduced with pyroxasulfone-based in-crop herbicide programs in twin-row GR soybean.展开更多
Field experiments (4 in total) were conducted in 2016 and 2017 in southwestern Ontario to compare the sensitivity of dry bean to four Group 15 herbicides applied preemergence (PRE). At 4 weeks after emergence (WAE), p...Field experiments (4 in total) were conducted in 2016 and 2017 in southwestern Ontario to compare the sensitivity of dry bean to four Group 15 herbicides applied preemergence (PRE). At 4 weeks after emergence (WAE), pethoxamid, S-metolachlor, dimethenamid-P and pyroxasulfone applied PRE at the 2X rate caused 5%, 9%, 9% and 14% visible injury in adzuki bean, 2%, 2%, 2% and 3% visible injury in kidney bean, 6%, 4%, 5% and 4% visible injury in small red Mexican (SRM) bean, and 9%, 6%, 8% and 9% visible injury in white bean, respectively. Pyroxasulfone reduced adzuki bean shoot biomass (m-1 row) 42% and height 12%. However, the other Group 15 herbicides did not reduce shoot biomass and height of adzuki bean. Kidney bean shoot biomass and height were not adversely affected by the Group 15 herbicides evaluated. S-metolachlor caused no adverse effect on SRM bean dry weight or height, but pethoxamid, dimethenamid-P and pyroxasulfone at the 2X rate reduced dry weight 26%, 28% and 28% and height 7%, 7% and 7% in SRM bean, respectively. Pethoxamid, S-metolachlor, dimethenamid-P, and pyroxasulfone applied PRE at the 2X rate reduced white bean dry weight 50%, 37%, 47% and 43% and height 16%, 10%, 16% and 15% in white bean, respectively. Pyroxasulfone (2X rate), applied PRE, reduced bean stand count and seed yield 12% and 7%, respectively. However, pethoxamid, S-metolachlor, and dimethenamid-P, applied PRE caused no decrease in stand count and seed yield of dry beans evaluated. In general, kidney and SRM bean are most tolerant, white bean is intermediate, and adzuki bean is most sensitive to Group 15 herbicides applied PRE.展开更多
Nine field experiments were conducted in 2011 and 2012 at various locations in southern Ontario, Canada to determine the tolerance of soybean (Glycine max (L.) Merr.) to herbicides inhibiting protoporphyrinogen oxidas...Nine field experiments were conducted in 2011 and 2012 at various locations in southern Ontario, Canada to determine the tolerance of soybean (Glycine max (L.) Merr.) to herbicides inhibiting protoporphyrinogen oxidase (Protox) and very long chain fatty acid (VLCFA) synthesis applied alone and in combination. Preemergence applications were evaluated for soybean injury, plant height, shoot dry weight, and yield in the absence of weed competition. Early-season soybean injury from the Protox inhibitors persisted 4 weeks after soybean emergence (WAE) with 3%, 5%, and 18% injury for flumioxazin, saflufenacil, and sulfentrazone, respectively. When Protox inhibitors were tank mixed with VLCFA inhibitors (i.e., dimethenamid-P, S-metolachlor, and pyroxasulfone), additive interactions were observed for injury with saflufenacil and sulfentrazone;whereas synergistic interactions were observed with flumioxazin. However, injury subsided over time decreasing from as much as 34% injury 1 WAE for the flumioxazin + S-metolachlor tank mix down to 9% injury 4 WAE. In general, when saflufenacil or flumioxazin were tank mixed with VLCFA inhibitors, greater than expected reductions in height and dry weight were observed indicating synergistic responses;while no interactive effects were detected with sulfentrazone and VLCFA inhibitor tank mixes. For the flumioxazin tank mixes that contained dimethenamid-P or S-metolachlor, the reduction in yield was greater than expected indicating synergistic interactive effects. Yet, all the demonstrated impacts were transient as the yield for soybean treated with any of the Protox inhibitor and VLCFA inhibitor tank mixes tested were similar to the untreated control. Therefore, usage restriction on these mixtures, based on perceived negative yield impact, should be lifted so the herbicides could be combined to expand weed control options.展开更多
文摘Downy brome is one of the most troublesome weeds in no-till wheat production systems of the US Great Plains. Pyroxasulfone is a relatively new, soil-applied residual herbicide (root/shoot growth inhibitor) labeled for use in wheat. Multiple field experiments were conducted near Huntley, MT from 2012 through 2016 to determine the efficacy of pyroxasulfone to control downy brome in imidazolinone (IMI)-tolerant (Clearfield™) winter wheat. Pyroxasulfone did not cause any injury to wheat in any of the three studies. Downy brome injury with pyroxasulfone preemergence (PRE) only program did not differ between 89 or 178 g·ai (active ingredient)·ha-1 rates, and averaged 82% and 84% in 2 separate studies. In a preplant (PP) burndown program, the addition of pyroxasulfone (178 g·ai·ha-1) to glyphosate improved downy brome end-season injury from 15% to 74%. In a separate study, the end-season injury with pyroxasulfone was greater when applied PRE (84%) compared to the delayed PRE (DPRE) timing (74%). In addition, the water dispersible granule (WDG) formulation of pyroxasulfone performed slightly better than the suspension concentrate (SC) formulation for downy brome injury. Pyroxasulfone applied PRE in the fall at a rate of 89 g·ai·ha-1 followed by (fb) imazamox (44 g·ai·ha-1 rate) applied postemergence (POST) in the spring effectively controlled downy brome (99% end-season injury). Furthermore, the injury was consistent with the standard program comprising of propoxycarbazone (29 g·ai·ha-1) PRE fb imazamox POST in IMI-tolerant winter wheat. In conclusion, pyroxasulfone applied PRE in the fall can be effectively utilized in conjunction with a standard acetolactate synthase (ALS)-inhibitor-based POST herbicide program for a season-long downy brome management in winter wheat.
文摘A field study was conducted at two locations in Kansas, USA in 2011 and 2012 to test weed control efficacy and crop response to preemergence-applied pyroxasulfone alone and in combination with sulfentrazone in sunflower. Treatments included three rates of pyroxasulfone (100, 200 and 400 g·ha-1) applied alone and tank-mixed with sulfentrazone at 70, 140 and 280 g·ha-1. Commercial standards sulfentrazone at 140 g·ha-1 + pendimethalin at 1390 g·ha-1 and sulfentrazone at 140 g·ha-1 + S-metolachlor at 1280 g·ha-1 were also included. Pyroxasulfone at 100 g·ha-1 controlled Palmer amaranth 87% at 3 weeks after application (WAA), but control decreased to 76% at 6 WAA. Increasing pyroxasulfone rate to ≥200 g·ha-1 or tank mixing with sulfentazone at 140 g·ha-1 provided ≥90% Palmer amaranth control for at least 6 WAA. Sulfentrazone alone at 70 g·ha-1 controlled Palmer amaranth 77% at 3 WAA, but control dropped to 69% at 6 WAA. Increasing sulfentrazone rate from 70 to 140 or 280 g·ha-1 increased control to >90% at 3 WAA, but did not maintain acceptable control at 6 WAA. Tank mixing sulfentrazone at 140 g·ha-1 with pendimethalin at 1390 g·ha-1 or S-metolachlor at 1280 g·ha-1 controlled Palmer amaranth ≥90 and 84% at 3 WAA and 6 WAA, respectively. The lowest rate of pyroxasulfone (100 g·ha-1) controlled kochia 98% and the control was complete with all other treatments. However, no treatment provided as much as 90% puncturevine control at 3 WAA and the control was commercially unacceptable (<75%) at 6 WAA. No treatment visibly injured sunflower anytime during the season or reduced sunflower plant population.
文摘Emergence of grasses late in the season has become a problem in glyphosate-resistant (GR) soybean production in the southern US. A 3-yr field study was conducted from 2011 to 2013 at Stoneville, MS to determine efficacy of post-harvest and pyroxasulfone-based in-crop herbicides on late-season grasses and yield in twin-row glyphosate-resistant soybean. Experiments were conducted in a split-plot arrangement of treatments in a randomized complete block design with fall herbicides (with and without pendimethalin at 1.12 kg ai ha-1 and paraquatat 0.84 kg ai ha-1) as main plots and in-crop herbicides as subplots with four replications. The six in-crop herbicide programs were: glyphosate applied early postemergence (EPOST) at 0.84 kg·aeha-1 followed by (fb) glyphosate late postemergence (LPOST) at 0.84 kg·ha-1 with and without pyroxasulfone preemergence (PRE) applied at 0.18 kg ai ha-1, pyroxasulfone PRE fb glyphosate at 0.84 kg·ha-1 LPOST or glyphosate at 0.84 kg·ha-1 + S-metolachlor at 1.68 kg ai ha-1 EPOST, pyroxasulfone PRE fb S-meto- lachlor at 1.12 kg·ha-1 + fomesafen at 0.27 kg ai ha-1 EPOST fb clethodim at 0.14 kg ai ha-1, and a no-herbicide control. Browntop millet, Digitaria spp., and junglerice densities at 2 weeks after LPOST, grass weed dry biomass at harvest, and soybean yield were similar regardless of post- harvest herbicides in all three years. At 2 weeks after LPOST, browntop millet, Digitaria spp. and junglerice densities were greatly reduced in all five in-crop herbicide treatments compared with no herbicide plot in all three years. Grass weed dry biomass in no-herbicide plots was 3346, 6136, and 6916 kg·ha-1 in 2011, 2012, and 2013, respectively and the five herbicide treatments reduced grass weed dry biomass by at least 87%, 84%, and 99% in 2011, 2012, and 2013, respectively. Soybean yield was higher with all five in-crop herbicide treatments compared to no herbicide control in all three years. These results indicate that browntop millet, Digitaria spp., and junglerice infestations can be reduced with pyroxasulfone-based in-crop herbicide programs in twin-row GR soybean.
文摘Field experiments (4 in total) were conducted in 2016 and 2017 in southwestern Ontario to compare the sensitivity of dry bean to four Group 15 herbicides applied preemergence (PRE). At 4 weeks after emergence (WAE), pethoxamid, S-metolachlor, dimethenamid-P and pyroxasulfone applied PRE at the 2X rate caused 5%, 9%, 9% and 14% visible injury in adzuki bean, 2%, 2%, 2% and 3% visible injury in kidney bean, 6%, 4%, 5% and 4% visible injury in small red Mexican (SRM) bean, and 9%, 6%, 8% and 9% visible injury in white bean, respectively. Pyroxasulfone reduced adzuki bean shoot biomass (m-1 row) 42% and height 12%. However, the other Group 15 herbicides did not reduce shoot biomass and height of adzuki bean. Kidney bean shoot biomass and height were not adversely affected by the Group 15 herbicides evaluated. S-metolachlor caused no adverse effect on SRM bean dry weight or height, but pethoxamid, dimethenamid-P and pyroxasulfone at the 2X rate reduced dry weight 26%, 28% and 28% and height 7%, 7% and 7% in SRM bean, respectively. Pethoxamid, S-metolachlor, dimethenamid-P, and pyroxasulfone applied PRE at the 2X rate reduced white bean dry weight 50%, 37%, 47% and 43% and height 16%, 10%, 16% and 15% in white bean, respectively. Pyroxasulfone (2X rate), applied PRE, reduced bean stand count and seed yield 12% and 7%, respectively. However, pethoxamid, S-metolachlor, and dimethenamid-P, applied PRE caused no decrease in stand count and seed yield of dry beans evaluated. In general, kidney and SRM bean are most tolerant, white bean is intermediate, and adzuki bean is most sensitive to Group 15 herbicides applied PRE.
文摘Nine field experiments were conducted in 2011 and 2012 at various locations in southern Ontario, Canada to determine the tolerance of soybean (Glycine max (L.) Merr.) to herbicides inhibiting protoporphyrinogen oxidase (Protox) and very long chain fatty acid (VLCFA) synthesis applied alone and in combination. Preemergence applications were evaluated for soybean injury, plant height, shoot dry weight, and yield in the absence of weed competition. Early-season soybean injury from the Protox inhibitors persisted 4 weeks after soybean emergence (WAE) with 3%, 5%, and 18% injury for flumioxazin, saflufenacil, and sulfentrazone, respectively. When Protox inhibitors were tank mixed with VLCFA inhibitors (i.e., dimethenamid-P, S-metolachlor, and pyroxasulfone), additive interactions were observed for injury with saflufenacil and sulfentrazone;whereas synergistic interactions were observed with flumioxazin. However, injury subsided over time decreasing from as much as 34% injury 1 WAE for the flumioxazin + S-metolachlor tank mix down to 9% injury 4 WAE. In general, when saflufenacil or flumioxazin were tank mixed with VLCFA inhibitors, greater than expected reductions in height and dry weight were observed indicating synergistic responses;while no interactive effects were detected with sulfentrazone and VLCFA inhibitor tank mixes. For the flumioxazin tank mixes that contained dimethenamid-P or S-metolachlor, the reduction in yield was greater than expected indicating synergistic interactive effects. Yet, all the demonstrated impacts were transient as the yield for soybean treated with any of the Protox inhibitor and VLCFA inhibitor tank mixes tested were similar to the untreated control. Therefore, usage restriction on these mixtures, based on perceived negative yield impact, should be lifted so the herbicides could be combined to expand weed control options.
