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J.E. Chafin, A.S. Culpepper, and L.B. Braxton University of Georgia
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- Palmer amaranth, benghal dayflower, and broadleaf signalgrass response to glufosinate applied alone or mixed with 2,4-D, or dicamba J.E. Chafin, A.S. Culpepper, and L.B. Braxton University of Georgia Department of Crop and Soil Sciences January 2010
- Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth. 2004 – 1 county 2005 – 2 counties 2006 – 7 counties 2007 – 10 counties 2008 – 18 counties
- Biotypes with multiple resistance to glyphosate and ALS herbicides are becoming more common across Georgia.
- 88 26 % acres 25 20 0 0 45 *Average of Macon, Taylor, Sumpter, Schley, and Dooly counties Glufos. (Ignite) systems Cultivation Hand weeding 0 Impact of GR Palmer amaranth in Georgia counties with severe infestations.* Acres (%) treated with at least two residual herbicide
- Dryland Conservation Tillage Prowl + Reflex PRE Roundup + Dual POST Direx + MSMA PD Prowl + Reflex PRE Ignite + Dual POST Direx + MSMA PD
- Glufosinate 0.42 lb on 5 in. Palmer amaranth “The challenge is making applications of glufosinate to target plants less than 10 cm in height” (Coetzer et al. 2002).
- Future Technology: 2,4-D or Dicamba Resistant Cotton 2,4-D resistant cotton 2,4-D sensitive cotton
- Objective Determine the response of glyphosate- resistant Palmer amaranth to glufosinate, 2,4-D (Weedar), or dicamba (Clarity) applied alone and glufosinate mixed with 2,4-D or dicamba. Carpetweed, benghal dayflower, broadleaf signalgrass, and pitted morningglory
- Hypothesis Tank mixtures of glufosinate + 2,4-D or dicamba will be more effective in controlling broadleaf weeds than glufosinate alone.
- Trial Locations Macon County (Glyphosate-resistant Palmer amaranth) Chula (Palmer amaranth, carpetweed) Sunbelt Expo (benghal dayflower, broadleaf signalgrass, pitted morningglory)
- Treatments A factorial arrangement of two “glufosinate” options and seven “tank mix” options Ignite Option: None or Ignite at 0.42 lbs Tank mix option: 2,4-D, dicamba, or none 2,4-D (Weedar 64) .5, 0.75, 1.0 lb/ac Dicamba (Clarity) .25, 0.5, 1.0 lb/ac None
- Application Methods Backpack sprayer Broadcast Overtop 15 gal/Ac Drift Guard T-Jet 11002 VS Early morning application 7-9 inch weed
- Conditions at Time of Application Moist/Wet Sunny conditions Air Temperature: 76-95 F % Relative Humidity: 56-74
- Data Reported & Statistical Analysis Palmer amaranth control was combined over the three locations. Carpetweed, benghal dayflower, broadleaf signalgrass, and pitted morningglory Weed control at 20 d is reported; interaction means are reported.
- Percent GR Palmer amaranth control at 20 d. Average 3 loc., GA, 2009. 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 69 cd 77 bc 73 bcd 79 b 65 d 77 bc 90 a Glufos-inate Herbicide applied alone
- Non-treated glufosinate 12 DAT
- 2,4-D at 0.75 lb 12 DAT 24 DAT
- dicamba 0.5 lb 12 DAT 24 DAT
- 69 cd 77 bc Glufos-inate 0.5 lb 73 bcd 79 b 65 d 77 bc 90 a 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 91 a 92 a 96 a 91 a 91 a 96 a = control when mixed with Ignite Percent GR Palmer amaranth control at 20 d. Average 3 loc., GA, 2009.
- glufosinate glufosinate + 2,4-D 0.75 lb 12 DAT
- glufosinate glufosinate + dicamba 0.5 lb 12 DAT
- 66 b 58 b Glufos-inate 0.5 lb 99 a 63 b 55 b 57 b 60 b 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba Percent carpetweed control at 20 d. Chula, GA, 2009.
- 2,4-D 0.5 lb at 10 DAT
- Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 99 a 99 a 99 a 99 a 99 a 99 a = control when mixed with Ignite Percent carpetweed control at 20 d. Chula, GA, 2009. 66 b 58 b 63 b 55 b 57 b 60 b 99 a
- Benghal dayflower infesting Roundup Ready cotton
- Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba Percent benghal dayflower control at 20 d. Sunbelt Expo, GA, 2009. 91 a 98 a 98 a 68 c 84 b 93 a 68 c
- Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 97 a 94 a = control when mixed with Ignite Percent benghal dayflower control at 20 d. Sunbelt Expo, GA, 2009. 91 a 98 a 98 a 68 c 84 b 93 a 68 c
- Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba Percent broadleaf signalgrass control at 20 d. Sunbelt Expo, GA, 2009. 96 a 0 b 0 b 0 b 0 b 0 b 0 b
- Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 93 ab 92 ab = control when mixed with Ignite Percent broadleaf signalgrass control at 20 d. Sunbelt Expo, GA, 2009. 91 ab 91 ab 88 b 92 ab 96 a
- Pitted morningglory controlled 97 to 99% by all treatments Everman et al. noted greater than 90% control with glufosinate applied POST on pitted morningglory.
- Conclusions-Palmer amaranth Glufosinate alone only provided 73% control 2,4-D alone provided 69-79% control Dicamba alone provided 69-90% Tank mixtures of glufosinate+2,4-D or dicamba at least 91% control
- Glufosinate alone provided 99% control 2,4-D alone provided 58-66% Dicamba alone provided 55-60% All rates of glufosinate+2,4-D or dicamba provided 99% control Conclusions-Carpetweed
- Conclusions- Benghal dayflower Glufosinate alone provided 63% control 2,4-D provided 91-98% control; combinations with glufosinate could not improve control Dicamba control ranges from 68-93% but when combined with glufosinate control ranges from 93-97%
- Conclusion-Broadleaf signalgrass Glufosinate alone provided 96% control and no control with 2,4-D or dicamba alone 2,4-D mixed with glufosinate, control ranged from 88-91%; at 1 lb/ac of 2,4-D the control was 8% less than glufosinate alone Dicamba mixed with glufosinate provided 92-93% control
- Future Research 2,4-D resistant cotton 2,4-D sensitive cotton
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