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2010 SWSS – Palmer amaranth response to 2,4-D Cotton Weed Management Programs.
AUTHOR
Stanley Culpepper
and Chaffin; University of Georgia
Braxton and Richburg; Dow AgroSciences
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TABLE OF CONTENTS
Control of Glyphosate-Resistant Palmer amaranth in DHT Cotton.
Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth.
Cultivation
Hand weeding cotton during 2009
Some of the hand weeding expense was from the removal of plants from the field.
GR Palmer amaranth control in dryland conservation tillage systems
Palmer Amaranth regrowth after being treated with Ignite.
2,4-D- Resistant Cotton Being Developed
Objective
Experiments
Experiment 1: Single Application
Factorial Treatment Arrangement
Percent GR Palmer amaranth control at 20 d.
Non-treated vs Ignite
Non-treated vs 1.5 pt 2,4-D
1.5 pt of 2,4-D
Non-treated vs Ignite + 2,4-D
Experiment 2: Systems - Residual programs
Experiment 2: Systems - Total POST programs
One inch of rainfall occurred within 5 days of planting and PRE treatments. Rainfall continued throughout the season.
Percent GR Palmer amaranth control 28 d after layby.
Percent GR Palmer amaranth control at harvest.
Seed Cotton Yield (lb/A).
Percent GR Palmer amaranth control comparing POST and residual programs 28 d after layby .
Non-treated Control (July 5)
Glyphosate-resistant Palmer amaranth response to sequential POST applications
Percent GR Palmer amaranth control with POST programs at harvest
Seed cotton yields (lb/A) with total POST programs
Summary
Summary
Summary
Conclusions
SLIDE CONTENTS
Control of Glyphosate-Resistant Palmer amaranth in DHT Cotton. Culpepper and Chaffin; University of Georgia Braxton and Richburg; Dow AgroSciences
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
Hand weeding cotton during 2009 52 counties surveyed Acres in survey: 799,000 Acres hand weeded: 437,660 54% cotton hand weeded $3 to $100/A Average $26 $11.4 million Grower Costs Acres Hand Weeded
Some of the hand weeding expense was from the removal of plants from the field.
GR Palmer amaranth control in dryland conservation tillage systems Prowl + Reflex PRE Roundup + Dual POST Diuron + MSMA PD Prowl + Reflex PRE Ignite + Dual POST Diuron + MSMA PD
Palmer Amaranth regrowth after being treated with Ignite.
2,4-D- Resistant Cotton Being Developed 2,4-D resistant cotton 2,4-D sensitive cotton
Objective Begin to determine the most effective 2,4-D weed management systems for glyphosate-resistant Palmer amaranth.
Experiments 1. Single application study (non-crop) 2. 2,4-D weed management systems (DHT cotton)
Experiment 1: Single Application Macon County (2 locations) Tift County (1 location)
Factorial Treatment Arrangement (Experiment 1: Single Application) 2,4-D (Weedar) Option: 0, 1.0, 1.5, or 2.0 pt/A Ignite Option: 0 or 29 oz/A Palmer was 8 inch at time of application (15 GPA)
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 2,4-D 69 cd 77 bc 73 bcd 79 b 91 a 92 a 96 a Ignite (29 oz) + Ignite
Non-treated Ignite 12 DAT
Non-treated 12 DAT 1.5 pt 2,4-D
1.5 pt of 2,4-D 12 DAT 24 DAT
Non-treated Ignite + 2,4-D 12 DAT
Experiment 2: Systems PRE Prowl Prowl Prowl Prowl POST (4-6” Palmer) Weedar Ignite + Weedar Ignite None Residual programs Direx + MSMA directed to all systems. Prowl 2.1 pt/A; Reflex 1 pt/A; Ignite 23 oz/A; Weedar 1.5 pt/A; Direx 2 pt/A; MSMA 2 lb ai/A. TRT 1 2 3 4 Prowl + Reflex Prowl + Reflex Prowl + Reflex Prowl + Reflex Weedar Ignite + Weedar Ignite None 5 6 7 8
Experiment 2: Systems POST 1 (4-6“ Palmer) Weedar Weedar + Ignite Ignite None POST 2 (3-6” Palmer) Weedar Weedar + Ignite Ignite None Total POST programs Direx + MSMA directed to all systems. Weedar 1.5 pt/A; Ignite 23 oz/A; Direx 2 pt/A; MSMA 2 lb ai/A. TRT 1 2 3 4
One inch of rainfall occurred within 5 days of planting and PRE treatments. Rainfall continued throughout the season.
Percent GR Palmer amaranth control 28 d after layby. Macon Co. GA, 2009. 86 bc 82 c 20 d 93 ab 99 a 99 a 99 a 2,4-D Ignite + 2,4-D None Prowl Ignite + Reflex Prowl Prowl Prowl + Reflex + Reflex + Reflex POST 2,4-D Ignite + 2,4-D None Ignite 82 c Direx + MSMA directed to all systems.
Percent GR Palmer amaranth control at harvest. Macon Co. GA, 2009. 48 c 50 c 81 b 90 a 90 a 93 a 2,4-D Ignite + 2,4-D None Prowl Ignite + Reflex Prowl Prowl Prowl + Reflex + Reflex + Reflex POST 2,4-D Ignite + 2,4-D None Ignite 43 c Direx + MSMA directed to all systems.
Seed Cotton Yield (lb/A). Macon Co. GA, 2009. 490 c 530 c 955 a 1120 a 1080 a 1100 a 2,4-D Ignite + 2,4-D None Prowl Ignite + Reflex Prowl Prowl Prowl + Reflex + Reflex + Reflex POST 2,4-D Ignite + 2,4-D None Ignite 140 d Direx + MSMA directed to all systems.
Percent GR Palmer amaranth control comparing POST and residual programs 28 d after layby . Macon Co. GA, 2009. 99 a 81 c 93 ab 94 a Ignite + 2,4-D Prowl + Reflex POST Ignite Ignite Ignite + 2,4-D 2,4-D 2,4-D Ignite + 2,4-D Ignite + 2,4-D 88 b Direx + MSMA directed to all systems. POST 2
Non-treated Control (July 5)
Ignite + 2,4-D Ignite + 2,4-D 2,4-D 2,4-D Glyphosate-resistant Palmer amaranth response to sequential POST applications. Macon Co., 2009.
93 a 50 c 81 b 85 b Ignite + 2,4-D Prowl + Reflex POST Ignite Ignite Ignite + 2,4-D 2,4-D 2,4-D Ignite + 2,4-D Ignite + 2,4-D 50 c Direx + MSMA directed to all systems. POST 2 Percent GR Palmer amaranth control with POST programs at harvest . Macon Co. GA, 2009.
1100 a 440 b 955 a 1026 a Ignite + 2,4-D Prowl + Reflex POST Ignite Ignite Ignite + 2,4-D 2,4-D 2,4-D Ignite + 2,4-D Ignite + 2,4-D 550 b Direx + MSMA directed to all systems. POST 2 Seed cotton yields (lb/A) with total POST programs. Macon Co. GA, 2009.
Summary (Experiment 1, Single Application) Ignite (29 oz) controlled GR Palmer amaranth 73% 2,4-D (1 to 2 pt) controlled GR Palmer amaranth 69-79% Ignite + 2,4-D controlled GR Palmer amaranth 91-96%
Summary (Experiment 2, Systems) Prowl fb 2,4-D or Ignite fb Direx + MSMA controlled Palmer 50%. Mixing Ignite with 2,4-D improved control at least 31%. Prowl plus Reflex fb Ignite, 2,4-D, or Ignite + 2,4-D controlled Palmer 90 to 93%. Total POST programs with sequential Ignite or 2,4-D applications provided only 50% control. Mixtures of Ignite plus 2,4-D improved control 35%. At harvest
Summary (Experiment 2, Systems) Prowl fb Ignite + 2,4-D fb Direx + MSMA Prowl + Reflex fb Ignite, 2,4-D or Ignite + 2,4-D fb Direx + MSMA Sequential Ignite + 2,4-D applications fb Direx + MSMA Highest seed cotton yields
Conclusions The addition of 2,4-D in a systems approach offers growers a significant advantage of managing emerged glyphosate-resistant Palmer amaranth Physical movement of 2,4-D is of great concern; however, research to address this is in progress