glyphosate-resistant palmer amaranth response to dicamba
Post on 11-Jan-2016
31 Views
Preview:
DESCRIPTION
TRANSCRIPT
Glyphosate-Resistant Palmer Amaranth Response
To Dicamba
R. D. Wallace, A. S. Culpepper, W. K. Vencill, A. C. York, and T. L. Grey
University of Georgia and NC StateDepartment of Crop and Soil Sciences
January 2008
Cotton In Georgia (2006)Most widely grown row crop1.4 million acres produced 2.3 million bales of cotton
National Agricultural Statistics Service, USDA
180
4,925
60
515
85
1,030
47
500
335
380
660
17551 860173
400
455
GA ranked second among cotton producing states in 2007
(thousands of acres)
National Agricultural Statistics Service, USDA
Glyphosate-Resistant Cotton
Glyphosate-resistant cotton was commercialized in 1997Rapidly adopted by growers
100
66
97
99
98
98
98
99
99
100
98
9883 9775
97
59
Percent of cotton acreage planted to RR varieties 2006
USDA, AMS. 2006. Publ. mp-cn833.
Advantages of Glyphosate-Resistant Cotton
Ease of systemProperties of glyphosateAgronomic value of the cotton– DP 555 BGR in GA
Control of Susceptible Palmer Amaranth by Glyphosate
Prior to 2005, glyphosate was an effective and economical tool
22 oz/A WeatherMax on 16” Palmer Amaranth
Glyphosate-Resistant Palmer Amaranth
Resistance to glyphosate in Palmer Amaranth was confirmed in 2005 in GAFactors influencing glyphosate-resistance in GA– Dependence on a single management tactic– Monocultural production system– Low use rates– Application in stressed situations
Glyphosate-Resistant Palmer Glyphosate-Resistant Palmer Amaranth in CottonAmaranth in Cotton
33 oz WeatherMax applied to 2” Palmer Amaranth
Georgia counties infested with glyphosate-resistant Palmer amaranth.
2005
2006
2007 (more sites being tested)
Confirmed in 83 of 149 fields sampled
Glyphosate-Resistant Palmer Amaranth
Current management tactics are not very successfulNew technology is neededDicamba-tolerant cotton (2014)
Objective
Determine glyphosate-resistant Palmer amaranth response to
dicamba programs.
Two Studies to Evaluate Palmer Amaranth Control by Clarity in
2007
Mount Olive
Macon Co.
*
*
Field Trial Macon Co. GA
4 Clarity rates: 4, 8, 12, or 16 oz/A3 Palmer amaranth heights: 3, 6, or 12”12 oz/A sequential application 21-30 days after initial Clarity applicationVisually evaluated for % control
Glyphosate-resistant Palmer amaranth control by Clarity. Macon
Co., GA 2007.
Evaluations 26 d after initial application
0
20
40
60
80
100
4 oz 8 oz 12 oz 16 oz
3 inch
45c
86b
97 a
99 a
% C
on
trol
Glyphosate-resistant Palmer amaranth control by Clarity. Macon
Co., GA 2007.
0
20
40
60
80
100
4 oz 8 oz 12 oz 16 oz
3 inch Sequential
Evaluations 23 d after sequential application
99a86
b
92ab
96a
% C
on
trol
Glyphosate-resistant Palmer amaranth control by Clarity. Macon
Co., GA 2007.
0
20
40
60
80
100
4 oz 8 oz 12 oz 16 oz
6 inch
91 a
Evaluations 24 d after initial application
65 b60
b
35c
% C
on
trol
Glyphosate-resistant Palmer amaranth control by Clarity. Macon
Co., GA 2007.
0
20
40
60
80
100
4 oz 8 oz 12 oz 16 oz
6 inch Sequential
98a91
a70 b
38c
Evaluations 23 d after sequential application
% C
on
trol
Glyphosate-resistant Palmer amaranth control by Clarity. Macon
Co., GA 2007.
0
20
40
60
80
100
4 oz 8 oz 12 oz 16 oz
12 inch
78a
46 b
46 b43
b
Evaluations 19 d after initial application
% C
on
trol
Glyphosate-resistant Palmer amaranth control by Clarity. Macon
Co., GA 2007.
0
20
40
60
80
100
4 oz 8 oz 12 oz 16 oz
12 inch Sequential
80a
55 b
58 b
43 c
Evaluations 23 d after sequential application
% C
on
trol
Clarity 8 oz/A
3 inch 6 inch
Clarity 16 oz/A
3 inch 6 inch
Field Trial Mt. Olive, NC
1 Palmer amaranth height: 6-7”5 Treatments of Clarity:– 8 oz/A – 8 oz/A fb 8 oz/A– 16 oz/A– 16 oz/A fb 8 oz/A– 16 oz/A fb 16 oz/A
Visually evaluated for % control
Glyphosate-resistant Palmer amaranth control by Clarity. Mt.
Olive, NC 2007.97a90
a
53c
63b
50 c
0
20
40
60
80
100
8 oz/0 oz 8 oz/8 oz 16 oz/0 oz 16 oz/8 oz 16 oz/16 oz
Evaluations 42 d after sequential application
% C
on
trol
Conclusions – Macon Co.
Palmer amaranth control was affected by plant size, Clarity rate, and the use of sequential applications>90% control was achieved when:– 3” Palmer amaranth
12 oz/A, 16 oz/A, 8 oz/A fb 12 oz/A
– 6” Palmer amaranth16 oz/A, 12 oz/A fb 12 oz/A, 16 oz/A fb 12 oz/A
Conclusions – Mt. Olive
Palmer amaranth control was affected by Clarity rate and the use of sequential applications>90% control was achieved when 6-7” Palmer amaranth was treated with 16 oz/A fb 8 oz/A and 16 oz/A fb 16 oz/A
Future Studies
Evaluate control of glyphosate-resistant Palmer amaranth through herbicide mixturesEvaluate control of other problematic row-crop weeds through herbicide mixtures
Acknowledgements
Committee MembersDr. Alan York
University of Georgia Weed Science Unit
top related