J.E. Chafin, A.S. Culpepper, and L.B. Braxton University of Georgia
description
Transcript of J.E. Chafin, A.S. Culpepper, and L.B. Braxton University of Georgia
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
Glyphosate 3 lb
Pyrithiobac 0.25 lb
Biotypes with multiple resistance to glyphosate and ALS herbicides are becoming more common across Georgia.
0
20
40
60
80
100
Before (2004) After (2008)
88
26
% a
cres
25 2000
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
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 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
0
20
40
60
80
100
69 cd
77 bc
Glufos-inate
0.5 lb
73 bcd
79 b
65 d
77 bc
90 a
0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
91 a 92 a 96 a91 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
0
20
40
60
80
100
66 b 58
b
Glufos-inate
0.5 lb
99 a
63 b 55
b57 b
60 b
0.75 lb 1.0 lb1.0 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
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 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
b57 b
60 b
99 a
Benghal dayflower infesting Roundup Ready cotton
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 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
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 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
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 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 b0 b0 b0 b0 b0 b
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 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