2011: impact of cover crop residue and tillage on the control of glyphosate-resistant palmer...
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2011: Impact of cover crop residue and tillage on the control of glyphosate-resistant Palmer amaranth
Staple + Reflex + Direx PRE
Roundup WMax + Parrlay POST
Direx + MSMA Layby
Palmer amaranth control before and after GR Palmer resistance in cotton!
Roundup
Roundup
Roundup
Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth.
2004 – 1 county
2005 – 2 counties
2006 – 7 counties
2007 – 11 counties
2008 – 18 counties
2009 – 13 counties
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
500,000
230 K
25028 K
309 K
Giant ragweed
450 K
Number of Seed Produced per Plant Glyphosate-Resistant Weeds in US
Ragweed = Harrison et al. 2001; johnsongrass = Warwick and Black (1983); horseweed = Regehr and Bazzaz (1979); waterhemp = Nordby and Hartzler (2004); Palmer amaranth = Macrae et al (2009).
Johnson-grass
Horseweed Waterhemp Palmer amaranth
Palmer amaranth seed production allows for rapid field domination
Year 1 Year 3 to 4
Role of pollen movement and gene-flow in the spread of herbicide resistance
In-field pollen movement
Distance (m) from source of resistance
1 5 10 25 50 75 100 150 200 250 300
% R
esis
tan
t o
ffsp
rin
g p
er p
aren
t p
lan
t
0
20
40
60
80
100
20062007
Amaranthus rudis Amaranthus palmeri
Tennessee
Missouri
Illinois
MississippiGeorgia
S Carolina
N Carolina
Alabama
Louisiana
Arkansas
GR pigweed in the mid-south and southeast
Steckel 2010
Can not survive with herbicides alone any longer
York 2010
Hand WeedingHand Weeding
2010: Herbicide input: $90 million
York 2010Hand WeedingHand Weeding
Over $16 million spent during 2010 ($23.70 on 53% of our acres)
Over $15 million spend during 2009
92% of GA growers handweeding 53% of the 2010 crop
Few growers Few growers
Most growers by far
Grower mentality of tillage vs. conservation tillage
0
20
40
60
80
100
Before (2004) After (2008)
5
% a
cres
*Average of Macon, Taylor, Sumpter, Schley, and Dooly counties
Herbicide Incorp.
0
Impact of GR Palmer amaranth in Georgia counties with severe infestations.*
Tillage in Cotton During 2010%PPI
tillage GA Counties#
0 0
1-9 Worth, Pualski, Tift, Berrien, Echols, Turner, Brooks, Pierce,
Marion, Grady,
10
10-19 Emanual, Montgomery, Atkins, Coffee, Lowndes, Dooly, Wilcox,
Thomas, Crisp, Schley, Webster
11
20-29 Bullock, Jefferson, Treutlen, Wheeler, Daugherty 5
30-50 Effingham, Telfair, Tattnall, Dodge, Toombs, Jeff Davis, Bleckly,
Early, Lanier, Irwin, Colquitt, Lee
13
>50 Jenkins, Johnson, Washington, Screven, Wayne, Laurens, Randolf,
Decatur, Seminole, Miller, Taylor Ben Hill
12
Although the agricultural community is committed to the benefits of conservation tillage, survival of the family farm is more critical.
Thus, understanding when tillage is required and determining how to implement tillage to compliment conservation tillage systems while having minimal impacts on the environment are needed if both the family farm and conservation tillage are expected to survive the threat of herbicide resistant weed.
LONG TERM GOAL
Objective
Develop an economically effective integrated program for the control of
GR Palmer amaranth in cotton.
Roundup applied three times starting on ½ Palmer provided no control
Four Tillage Options
Deep Inversion
(12 to 16 inches)
Strip into weeds
Four Tillage Options
Deep inversion
followed by RyeHeavy residue
(1.5 bu/A)
Staple + Reflex + Direx PRE
Roundup WMax + Parrlay POST
Direx + MSMA Layby
Palmer amaranth control of 95% achieved by herbicide program!
GR Palmer amaranth control by tillage and cover crop residue. 2009 & 2010. 21 DAP.*
0
20
40
60
80
100
0 d
50 c60 b
Weeds
*No herbicide
Inversion + rye
Deep inversion
75 a
Rye
%
In the rye, control loss was in the strip
GR Palmer amaranth control by tillage, cover crop residue, and herbicides. 2009 & 2010 At harvest.*
0
20
40
60
80
100
76 b 78 b
Weeds
*RR System: Diuron + Reflex + Staple fb Roundup + Parrlay fb Direx + MSMA
Inversion + rye
Deep inversion
94 a
Rye
%59 c
Staple + Reflex + Direx PRE
Roundup WMax + Parrlay POST
Direx + MSMA Layby
Weeds Deep Tillage
Palmer amaranth response to deep tillage. Macon County, GA. 2009.
Staple + Reflex + Direx PRE
Roundup WMax + Parrlay POST
Direx + MSMA Layby
Weeds Rye cover
Palmer amaranth response to cover crops. Macon County, GA. 2009.
Staple + Reflex + Direx PRE
Roundup WMax + Parrlay POST
Direx + MSMA Layby
Weeds
Palmer amaranth response to deep tillage and cover crops. Macon County, GA. 2009.
Deep tillage
Rye cover crop
GR Palmer amaranth influence on cotton lint yield (lb/A) in the Roundup system.*
0
200
400
600
800
592 c690 b
Weeds
*RR System: Diuron + Reflex + Staple fb Roundup + Parrlay fb Direx + MSMA
Inversion + rye
Deep inversion
790 a
Rye
480 d
Dryland Conservation Tillage
Prowl + Reflex PRE
Roundup + Dual POST
Diuron + MSMA PD
Prowl + Reflex PRE
Ignite + Dual POST
Diuron + MSMA PD
Applications must be timely with Ignite
GR Palmer amaranth control by tillage, cover crop residue, and herbicides. 2009 & 2010. At harvest.*
0
20
40
60
80
10099 a 99 a
Weeds
*Ignite System: Diuron + Reflex + Staple fb Ignite + Parrlay fb Direx + MSMA
Inversion + rye
Deep inversion
99 a
Rye
%
94 b
0
200
400
600
800
680 bc710 ab
Weeds
*Ignite System: Diuron + Reflex + Staple fb Ignite + Parrlay fb Direx + MSMA
Inversion + rye
Deep inversion
770 a
Rye
%
625 c
GR Palmer amaranth influence on cotton lint yield in the Ignite system. 2009 & 2010.*
1. Strip tillage into weeds
2. Strip tillage into rye.
3. Strip tillage into rye/deep turning.
ON FARM STUDIES
Tillage/Cover Crop Options
Influencing Palmer Emergence(On farm study, TN)
WeedsRye
(large)
Deep Turn
+ Rye
101
10 sq m
45
10 sq m
44
10 sq m
Influencing Palmer Emergence(On farm 10 acre study, Macon Co. Georgia)
WeedsRye
(large)
Deep Turn
+ Rye
Gram. + Direx BD; Prowl + Reflex PRE; RU + Dual POST;
Direx + MSMA layby
8242
plants/A
4371
plants/A
446
plants/A
No Deep Tillage Deep Turn
No Herbicide Treatment
Number of Palmer Amaranth Plants During Early Season. Macon Co., Georgia 2008.*
Influence of burial depth on Palmer amaranth emergence
Depth of burial (inches)
0.5" 1" 4" 16"
Pe
rce
nt (
%)
em
erg
en
ce
0
10
20
30
40
50S-Palmer amaranthR-Palmer amaranth
Keeley et al. (1987) reported 36-44% emergence at 0-1”, 7% at 2”, and 2% at 3”.
Length of burial (months)
0 6 12 18 24 30
Per
cent
(%
) ge
rmin
atio
n
0
20
40
60
80
100
Palmer amaranth seed germination as affected by length of burial
Depth of burial (inches)
0.5 1 4 16
Per
cent
(%
) ge
rmin
atio
n
30
40
50
60
70
Palmer amaranth seed germination as affected by depth of burial
1.Work together!
2. Integrated programs are required to control GR Palmer amaranth in cotton.
3.Deep turning, rye cover, and deep turing + rye will greatly improve control.
4. Incentives to assist in grower adoption of heavy residue.
5.Find more funds to expand NRCS Pilot Program.
SUSTAINING COTTON PRODUCTION
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