control of glyphosate-resistant palmer amaranth in dht cotton
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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
20
40
60
80
100
0.5 lb 0.75 lb 1.0 lb1.0 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.
0
20
40
60
80
100
86 bc
82 c
20 d
93 ab
99 a
99 a
99 a
2,4-D Ignite + 2,4-D
None
Prowl
Ignite
+ ReflexProwl ProwlProwl
+ 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.
0
20
40
60
80
100
48 c
50 c
81 b
90 a
90 a
93 a
2,4-D Ignite + 2,4-D
None
Prowl
Ignite
+ ReflexProwl ProwlProwl
+ 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.
0
300
600
900
1200
490 c
530 c
955 a
1120 a
1080 a
1100 a
2,4-D Ignite + 2,4-D
None
Prowl
Ignite
+ ReflexProwl ProwlProwl
+ 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.
0
20
40
60
80
10099 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.
0
20
40
60
80
100
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.
0
300
600
900
1200
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