Weed Control in Conventional No-Tillage Soybeans
Final Research Report Submitted to Delaware Soybean Board
WEED CONTROL IN CONVENTIONAL NO-TILLAGE SOYBEANS Submitted by Mark VanGessel Extension Specialist / Professor University of Delaware 16483 County Seat Highway Georgetown, DE 19947 Phone: 302/ 856-7303 (ext 510) Fax: 302/ 856-1845 e-mail: [email protected] Summary Comparing various soil-applied and/or postemergence herbicides for weed control in conventional soybeans only Canopy SP plus Dual Magnum or FirstRate plus Valor SX plus Dual Magnum provided excellent control of all broadleaf weeds through harvest and were fair to good for grass control. All postemergence treatments provided excellent control of all the broadleaf weeds present in the study. The addition of Select with either Reflex or Synchrony eliminated the benefit of the soil-applied herbicides in this trial. Synchrony plus Select provided excellent weed control and chemical cost was only $16/A. When evaluating the benefit of Valor SX for soybean weed control, Valor SX can improve overall weed control for many of the weeds found in Delaware. Valor SX at 2 oz/A is adequate when highly susceptible species such as pigweed or common lambsquarters are present. However, 3 oz/A is needed for control of other species such as common ragweed, common cocklebur, or morningglory (at an additional cost of $4.5/A over the 2 oz rate). Note: Since this proposal was submitted, DuPont has decided to continue marketing Canopy SP.
Background There has been increased interest in herbicide programs that do not rely on glyphosate-resistant soybeans (Roundup Ready Soybeans) for a variety of reasons. The recent loss of Canopy XL as a standard broadleaf herbicide intended for soil-application prior to planting has complicated weed management options for conventional soybeans. Canopy XL contained both Classic (chlorimuron) and Authority (sulfentrazone). The Authority portion of this product is excellent for common lambsquarters and morningglory control. Another option is Valor SX (flumioxazin) which controls these two troublesome weed species. When Valor was first introduced (in 2002), the label did not allow it to be
tankmixed with residual grass herbicides, such as Dual Magnum. In the spring of 2005, the Valor label was modified to allow application with residual grass herbicides, opening more options for its use. Thus, current situations require a re-evaluation of herbicide programs in conventional (non-RR) soybeans and a better understanding of how (or if) Valor will benefit Delaware soybean producers. The following are two field trials with a justification for each and a brief methodology. 1. Conventional (non-RR) Soybean Weed Control Under No-till Conditions The objective of this study is to examine a range of herbicide programs for weed control under no-till conditions focusing on replacements for Canopy SP and Canopy XL. Treatments included soil-applied applications and/or postemergence applications. Treatments and associated costs are listed in Table 1. 2. Utility of Valor SX for Delaware Soybean Producers The objective of this study is to identify utility of Valor SX for Delaware soybean producers. All applications were soil-applied. Treatments and associated costs are listed in Table 2 Methods: Soybeans (Southern States 381STS) were planted on May 19, 2006 at UD-REC into small grain stubble. Entire experimental area was treated with paraquat prior to planting to control winter annual weeds. Preemergence herbicides were applied immediately after planting. Postemergence herbicides were applied 3 weeks after planting. The research site did not receive precipitation for thirteen days following preemergence herbicide application, which resulted in poor weed control. As a result, a second site (Asbury Church site) was planted on June 6. The same variety was used for the non-RR trial while RT4502N was used for the Valor SX study. The weed density was low and species were variable at the second site resulting in poor weed control data. Treatments were all applied in 25 GPA of water. Weed control and injury were rated visually. Plots were machine harvested and yields converted to bushels per acre. Prices of the treatments are based on average price listed and are not intended as exact costs, rather to provide a relative difference between costs of the programs (Table 3). Costs include the application costs. Results:
VanGessel: Soybean Weed Control - 2
General comments: No herbicide injury was observed in either study. A hard rain that occurs just a soybeans are emerging can cause soil treated with Valor to splash onto the stems and leaves resulting in herbicide injury. However, the presence of crop residue (no-till system) and lack of rain prevented any risk of injury. A STS variety was used in these trials which eliminated any potential injury from Synchrony applied postemergence. Control of winter annual weeds was excellent with the paraquat treatment. Paraquat was applied as a separate procedure. Conventional soybean trial: Dual Magnum applied at planting was not adequate for full season grass control (Table 4). At 7 weeks after application, Dual provided 53 to 88% control depending on tank-mix partner. Lorox provided more grass suppression than Sencor, resulting in slightly higher level of grass control with Lorox combinations. This additional control (compared to Dual alone) was not commercially acceptable, but was noticeable in the trial, even through harvest. Of the treatments with only soil-applied herbicides (treatments 2 through 10), only two (treatments 6 and 10) provided acceptable weed control. These treatments were Canopy SP plus Dual Magnum or FirstRate plus Valor SX plus Dual Magnum. These treatments provided excellent control of all broadleaf weeds through harvest and fair to good for grass control. It was surprising to see such good control when precipitation was so limited. However, dry soil conditions early in the season prevented weed seed germination. Germination did not occur until rainfall, which also “activated” the soil-applied herbicides. All postemergence treatments (treatments 11 through 18) provided excellent control of all the broadleaf weeds present in the study (Table 4). The soil-applied application of Dual plus Lorox provided good to excellent grass control, eliminating the need for a postemergence application of Select. The practice of using soil-applied treatments may provide a broader application window for postemergence, but that was not investigated in this trial. Conversely, the addition of Select with either Reflex or Synchrony eliminated the benefit of the soil-applied herbicides in this trial. Synchrony plus Select provided excellent weed control and chemical cost was only $16/A. Weed density at Asbury Church field was quite sparse. Weed density was not great enough to impact yield. All treatments provided excellent control. Valor SX trial: All treatments provided excellent pigweed and lambsquarters control, except Sencor plus Dual (Table 5). Common ragweed control was excellent for all treatments containing Valor, except Valor at 2 oz plus Lorox and Dual. If Valor SX was tankmixed with another herbicide, or Valor rate was increased to 3 oz, common ragweed control was >86%.
VanGessel: Soybean Weed Control - 3
FirstRate plus Valor at 3 oz or Canopy plus Valor at 3 oz provided the highest level of control for all species present. However, both of these treatments were approximately $40/A (Table 2). The best method to determine the benefit of Valor SX is to compare Canopy plus Dual or Lorox plus Dual applied without Valor or with 2 or 3 oz/A of Valor. Canopy was good to excellent on all the species in this trial; while Lorox plus Dual was fair to good, depending on the species present (Figure 1). There was a step-wise increase in control with increasing rates of Valor. This was most notable with the Lorox plus Dual treatments. There was an additional $4.50/A cost of increasing Valor from 2 oz to 3 oz; however, there was also a significant increase in weed control. Sencor plus Dual provided only 67% control of common lambsquarters. However, the addition of 2 oz/A of Valor improved control to 100% (Table 5). This indicates Valor is very effective on common lambsquarters. Pigweed was also very sensitive to Valor, with control improving to 100% with the addition of 2 oz/A of Valor, compared to Sencor or Lorox alone. This was also observed at Asbury Church. Valor SX can improve overall weed control for many of the weeds found in Delaware. Valor SX at 2 oz/A is adequate when highly susceptible species such as pigweed or common lambsquarters are present. However, 3 oz/A is needed for control of other species such as common ragweed, common cocklebur, or morningglory. No yield differences were observed with any treatment. At UD-REC, the soybean stand was poor due to dry conditions at planting. As a result, yields were quite variable and it was difficult to detect significant differences. At Asbury Church site, the weed density was quite sparse and there was not enough weed pressure to impact yields.
VanGessel: Soybean Weed Control - 4
Table 1. Treatments for non-Roundup Ready™ soybeans trial. Trt No. 1 2 3 4
5
6
7 8 9
10
11
12
13
14
Treatment Name Untreated Check Sencor Dual II Magnum Lorox Dual II Magnum Sencor Lorox Dual II Magnum Boundary Premix ----s-metolachlor ----metribuzin Canopy SP Premix ----metribuzin ----chlorimuron Dual II Magnum Sencor Dual II Magnum Lorox Dual II Magnum Lorox Sencor Dual II Magnum Firstrate Valor SX Dual II Magnum Valor SX Synchrony XP Premix ----chlorimuron ----thifensulfuron Select Crop Oil Concentrate Dual II Magnum Synchrony XP Premix ----chlorimuron ----thifensulfuron Crop Oil Concentrate Dual II Magnum Lorox Synchrony XP Premix ----chlorimuron ----thifensulfuron Crop Oil Concentrate Synchrony XP Premix ----chlorimuron ----thifensulfuron Select
Product Rate
Product Rate Unit
Timing
4 1 0.5 1 4 0.5 1 1.25
oz wt/A pt/A lb/A pt/A oz wt/A lb/A pt/A pt/A
PRE PRE PRE PRE PRE PRE PRE PRE
5
oz wt/A
PRE
1 5 1 1 1 1 5 1 0.4 2 1 2 0.75
pt/A oz wt/A pt/A lb/A pt/A lb/A oz wt/A pt/A oz wt/A oz wt/A pt/A oz/A oz wt/A
PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE POST
6 1 1 0.75
fl oz/A qt/A pt/A oz wt/A
POST
1 1 0.5 0.75
1 0.75
6
Cost ($/A) 0.00 21.50 25.72 29.50
15.74
31.71
22.45 33.72 38.45
37.39
36.60
PRE POST
30.79
qt/A pt/A lb/A oz wt/A
PRE PRE POST
38.79
qt/A oz wt/A
POST
21.92
fl oz/A
POST
VanGessel: Soybean Weed Control - 5
15
16
17
18
Crop Oil Concentrate Valor SX Reflex Select Nonionic Surfactant Dual II Magnum Reflex Nonionic Surfactant Lorox Dual II Magnum Reflex Nonionic Surfactant Reflex Select Nonionic Surfactant
1 2 1 6 0.25 1 1 0.25 0.5 1 1 0.25 1 6 0.25
qt/A oz/A pt/A fl oz/A % v/v pt/A pt/A % v/v lb/A pt/A pt/A % v/v pt/A fl oz/A % v/v
PRE POST POST
43.73
PRE POST
37.92
PRE PRE POST
53.92
POST POST
29.05
VanGessel: Soybean Weed Control - 6
Table 2. Treatments to evaluate utility of Valor for Delaware soybean production. Trt No. 1 2
3
4
5
6
7
8
9
10 11 12
13
14
Treatment Name Untreated Check Valor SX Lorox Dual II Magnum Valor SX Sencor Dual II Magnum Valor SX Lorox Sencor Dual II Magnum Valor SX Boundary Premix ----s-metolachlor ----metribuzin Valor SX Canopy SP Premix ----metribuzin ----chlorimuron Dual II Magnum Valor SX Firstrate Dual II Magnum Valor SX Canopy SP Premix ----metribuzin ----chlorimuron Dual II Magnum Valor SX Lorox Dual II Magnum Lorox Dual II Magnum Sencor Dual II Magnum Lorox Sencor Dual II Magnum Boundary Premix ----s-metolachlor ----metribuzin Canopy SP Premix ----metribuzin ----chlorimuron Dual II Magnum
Product Rate
Product Rate Unit
2 1 1 2 4 1 2 0.5 4 1 2 1.25
oz/A lb/A pt/A oz/A oz wt/A pt/A oz/A lb/A oz wt/A pt/A oz/A pt/A
PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE
2 5
oz/A oz wt/A
PRE PRE
1 2 0.5 1 3 5
pt/A oz/A oz wt/A pt/A oz/A oz wt/A
PRE PRE PRE PRE PRE PRE
1 3 1 1 1 1 4 1 0.5 4 1 1.25
pt/A oz/A lb/A pt/A lb/A pt/A oz wt/A pt/A lb/A oz wt/A pt/A pt/A
PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE
5
oz wt/A
PRE
1
pt/A
PRE
Cost ($/A) 0.00 42.40
30.18
38.18
24.42
40.39
40.14
44.73
46.74
33.72 21.50 29.50
15.74
31.71
VanGessel: Soybean Weed Control - 7
Table 3. Estimated herbicide and application costs based on an average from various distributors. Costs will vary, but the intent is to provide relative costs of treatments. Herbicide / Product Boundary Premix Canopy SP Premix Dual II Magnum Firstrate Firstrate Lorox Lorox Reflex Select Sencor Sencor Synchrony XP Premix Valor SX Valor SX Crop Oil Concentrate Nonionic Surfactant Application cost
Rate 1.25 5 1 0.4 0.5 0.5 1 1 6 4 5 0.75 2 3 1 0.25
Rate unit pt/A oz wt/A pt/A oz wt/A oz wt/A lb/A lb/A pt/A fl oz/A oz wt/A oz wt/A oz wt/A oz/A oz/A qt/A % v/v
Cost ($/A) 9.74 13.99 11.72 10.99 13.74 8.00 16.00 12.50 8.85 3.78 4.73 4.77 8.68 13.02 2.30 1.70 6.00
VanGessel: Soybean Weed Control - 8
Table 4. Weed control and yield at UD-REC site for herbicide programs intended for conventional soybeans. Weed density was sparse at Asbury Church field. Visual ratings from 7/11/06 were 7 weeks after planting and/or 3 weeks after postemergence applications.
Trt. 1 2 3 4
5 6 7 8 9
10
11
12
Herbicide Untreated Check Sencor Dual II Magnum Lorox Dual II Magnum Sencor Lorox Dual II Magnum Boundary Canopy SP Dual II Magnum Sencor Dual II Magnum Lorox Dual II Magnum Lorox Sencor Dual II Magnum Firstrate Valor SX Dual II Magnum Valor SX Synchrony XP Select Crop Oil Conc. Dual II Magnum Synchrony XP Crop Oil Conc.
Product 4 1 0.5 1 4 0.5 1 1.25 5 1 5 1 1 1 1 5 1 0.4 2 1 2 0.75 6 1 1 0.75 1
rate
Timing
oz wt/A pt/A lb/A pt/A oz wt/A lb/A pt/A pt/A oz wt/A pt/A oz wt/A pt/A lb/A pt/A lb/A oz wt/A pt/A oz wt/A oz wt/A pt/A oz/A oz wt/A fl oz/A qt/A pt/A oz wt/A qt/A
PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE POST POST PRE POST
PANDI
AMBEL
IPOSS
XANST
AMACH
GGGAN
ANNBR
Fall Panicum Control % 7/11/2006 0 f 62 de
Common Ragweed Control % 7/11/2006 0 e 23 d
Mornglry Species Control % 7/11/2006 0 e 20 cde
Common Cocklebr Control % 7/11/2006 0 c 50 b
Smooth Pigweed Control % 7/11/2006 0 d 70 bc
Annual Grasses Control % 10/13/2006 0 e 41 d
Annual Broadlvs Control % 10/13/2006 0 g 40 e
65
de
40
c
23
cd
68
de
50
bc
22
cd
100
63 75
de bcd
10 95
de a
10 96
de a
53
e
50
bc
37
73
cd
43
bc
78
bcd
57
88
abc
100
77
GLXMA Soybean Yield Bu/A 11/1/2006 16 f 23 ef
50
c
77
ab
40
e
31
b-e
a
100
a
73
ab
60
b
27
c-f
0 99
c a
80 99
ab a
50 71
bcd abc
50 100
d a
25 43
def a
bc
60
b
70
bc
42
cd
30
f
36
a-d
47
b
100
a
100
a
80
a
60
b
36
a-d
b
27
bcd
65
b
100
a
77
ab
55
c
33
a-e
97
a
93
a
100
a
100
a
89
a
100
a
33
a-e
a
100
a
100
a
100
a
100
a
96
a
100
a
34
a-d
bcd
100
a
100
a
100
a
100
a
78
ab
100
a
39
ab
13
Dual II Magnum Lorox Synchrony XP Crop Oil Conc. 14 Synchrony XP Select Crop Oil Conc. 15 Valor SX Reflex Select Nonionic Surfact. 16 Dual II Magnum Reflex Nonionic Surfact. 17 Lorox Dual II Magnum Reflex Nonionic Surfact. 18 Reflex Select Nonionic Surfact. LSD (P=.05) CV Treatment Prob(F)
1 0.5 0.75 1 0.75 6 1 2 1 6 0.25 1 1 0.25 0.5 1 1 0.25 1 6 0.25
pt/A lb/A oz wt/A qt/A oz wt/A fl oz/A qt/A oz/A pt/A fl oz/A % v/v pt/A pt/A % v/v lb/A pt/A pt/A % v/v pt/A fl oz/A % v/v
PRE PRE POST
90
abc
100
a
92
a
100
a
100
a
85
a
100
a
36
abc
POST POST
100
a
100
a
100
a
100
a
100
a
99
a
98.3
a
40
ab
PRE POST POST
100
a
100
a
99
a
100
a
100
a
100
a
100
a
43
a
PRE POST
78
bcd
100
a
100
a
100
a
100
a
87
a
100
a
36
a-d
PRE POST
93
ab
100
a
95
a
100
a
100
a
96
a
98
a
44
a
POST POST
100
a
100
a
100
a
100
a
100
a
97
a
97
a
40
ab
20 15 0.0001
15 13 0.0001
21 19 0.0001
29 21 0.0001
27 18 0.0001
29 24 0.0001
Means followed by same letter do not significantly differ (P=.05, LSD) Mean comparisons performed only when AOV Treatment P(F) is significant at mean comparison OSL.
VanGessel: Soybean Weed Control - 10
5 4 0.0001
12 20 0.0007
Table 5. Evaluation of Valor SX as a tankmix partner with soil-applied herbicides for weed control and yield. All treatments applied at planting and ratings were taken 7 weeks after planting.
Trt. 1 2
3
4
5 6
7
8
9
10
Herbicide Product Untreated Check Valor SX 2 Lorox 1 Dual II Magnum 1 Valor SX 2 Sencor 4 Dual II Magnum 1 Valor SX 2 Lorox 0.5 Sencor 4 Dual II Magnum 1 Valor SX 2 Boundary 1.25 Valor SX 2 Canopy SP 5 Dual II Magnum 1 Valor SX 2 Firstrate 0.5 Dual II Magnum 1 Valor SX 3 Canopy SP 5 Dual II Magnum 1 Valor SX 3 Lorox 1 Dual II Magnum 1 Lorox 1 Dual II Magnum 1
rate oz/A lb/A pt/A oz/A oz wt/A pt/A oz/A lb/A oz wt/A pt/A oz/A pt/A oz/A oz wt/A pt/A oz/A oz wt/A pt/A oz/A oz wt/A pt/A oz/A lb/A pt/A lb/A pt/A
AMACH Smooth Pigweed Control % 7/11/2006 0 c 100 a
AMBEL Common Ragweed Control % 7/11/2006 0 e 73 bcd
100
a
87
100
a
100
100
a
87
100
a
100
XANST Common Cocklebr Control % 7/11/2006 0 d 62 b
UD-REC CHEAL Common Lambqtrs Control % 7/11/2006 0 c 100 a
IPOSS Mornglry Species Control % 7/11/2006 0 g 62 bcd
Soybean Yield Bu/A 11/1/2006 25 a 30 a
Asbury Church Field AMACH Pigweed Species Soybean Control Yield % Bu/A 7/12/2006 11/1/2006 0 d 43 a 100 a 45 a
abc
30
c
100
a
55
de
35
a
100
a
43
a
a
35
c
100
a
57
cde
37
a
95
ab
45
a
abc
40
bc
100
a
62
bcd
38
a
100
a
43
a
100
a
93
a
100
a
88
ab
39
a
100
a
43
a
a
100
a
95
a
100
a
100
a
33
a
100
a
42
a
100
a
100
a
100
a
100
a
97
a
36
a
100
a
44
a
100
a
100
a
90
a
100
a
88
ab
46
a
100
a
44
a
95
ab
50
d
40
bc
100
a
33
ef
29.6
a
81
bc
42
a
VanGessel: Soybean Weed Control - 11
11
Sencor Dual II Magnum 12 Lorox Sencor Dual II Magnum 13 Boundary 14 Canopy SP Dual II Magnum LSD (P=.05) CV Treatment Prob(F)
4 1 0.5 4 1 1.25 5 1
oz wt/A pt/A lb/A oz wt/A pt/A pt/A oz wt/A pt/A
77
b
50
d
0
d
67
b
37
def
36
a
100
a
45
a
93
ab
65
cd
40
bc
100
a
33
ef
30
a
70
c
40
a
100 100
a a
20 95
e ab
20 87
cd a
87 100
ab a
23 83
fg abc
33 31
a a
95 100
ab a
42 42
a a
20 13 0.0001
25 20 0.0001
25 27 0.0001
27 18 0.0001
27 28 0.0001
17 29 0.6556
Means followed by same letter do not significantly differ (P=.05, LSD) Mean comparisons performed only when AOV Treatment P(F) is significant at mean comparison OSL.
VanGessel: Soybean Weed Control - 12
18 12 0.0001
5 7 0.6318
Figure 1. Weed control with the addition of Valor to other soil-applied herbicides.
100
Visual control (%)
90 80 70 60 50 40
Canopy (5 oz/A) + Dual (1 pt/A)
30 20 10 0
ry
Visual control (%)
ur
o gl
80
eb kl oc C
ng ni or
M
d ee
90
w ag R
100
70 60 50 40 30 20 10
Lorox (1 lb/A) + Dual (1 pt/A)
0
eb kl oc C ur
o gl
d ee
ng ni or
M
w ag R
ry No Valor Valor at 2 oz/A Valor at 3 oz/A
WEED CONTROL IN CONVENTIONAL NO-TILLAGE SOYBEANS Submitted by Mark VanGessel Extension Specialist / Professor University of Delaware 16483 County Seat Highway Georgetown, DE 19947 Phone: 302/ 856-7303 (ext 510) Fax: 302/ 856-1845 e-mail: [email protected] Summary Comparing various soil-applied and/or postemergence herbicides for weed control in conventional soybeans only Canopy SP plus Dual Magnum or FirstRate plus Valor SX plus Dual Magnum provided excellent control of all broadleaf weeds through harvest and were fair to good for grass control. All postemergence treatments provided excellent control of all the broadleaf weeds present in the study. The addition of Select with either Reflex or Synchrony eliminated the benefit of the soil-applied herbicides in this trial. Synchrony plus Select provided excellent weed control and chemical cost was only $16/A. When evaluating the benefit of Valor SX for soybean weed control, Valor SX can improve overall weed control for many of the weeds found in Delaware. Valor SX at 2 oz/A is adequate when highly susceptible species such as pigweed or common lambsquarters are present. However, 3 oz/A is needed for control of other species such as common ragweed, common cocklebur, or morningglory (at an additional cost of $4.5/A over the 2 oz rate). Note: Since this proposal was submitted, DuPont has decided to continue marketing Canopy SP.
Background There has been increased interest in herbicide programs that do not rely on glyphosate-resistant soybeans (Roundup Ready Soybeans) for a variety of reasons. The recent loss of Canopy XL as a standard broadleaf herbicide intended for soil-application prior to planting has complicated weed management options for conventional soybeans. Canopy XL contained both Classic (chlorimuron) and Authority (sulfentrazone). The Authority portion of this product is excellent for common lambsquarters and morningglory control. Another option is Valor SX (flumioxazin) which controls these two troublesome weed species. When Valor was first introduced (in 2002), the label did not allow it to be
tankmixed with residual grass herbicides, such as Dual Magnum. In the spring of 2005, the Valor label was modified to allow application with residual grass herbicides, opening more options for its use. Thus, current situations require a re-evaluation of herbicide programs in conventional (non-RR) soybeans and a better understanding of how (or if) Valor will benefit Delaware soybean producers. The following are two field trials with a justification for each and a brief methodology. 1. Conventional (non-RR) Soybean Weed Control Under No-till Conditions The objective of this study is to examine a range of herbicide programs for weed control under no-till conditions focusing on replacements for Canopy SP and Canopy XL. Treatments included soil-applied applications and/or postemergence applications. Treatments and associated costs are listed in Table 1. 2. Utility of Valor SX for Delaware Soybean Producers The objective of this study is to identify utility of Valor SX for Delaware soybean producers. All applications were soil-applied. Treatments and associated costs are listed in Table 2 Methods: Soybeans (Southern States 381STS) were planted on May 19, 2006 at UD-REC into small grain stubble. Entire experimental area was treated with paraquat prior to planting to control winter annual weeds. Preemergence herbicides were applied immediately after planting. Postemergence herbicides were applied 3 weeks after planting. The research site did not receive precipitation for thirteen days following preemergence herbicide application, which resulted in poor weed control. As a result, a second site (Asbury Church site) was planted on June 6. The same variety was used for the non-RR trial while RT4502N was used for the Valor SX study. The weed density was low and species were variable at the second site resulting in poor weed control data. Treatments were all applied in 25 GPA of water. Weed control and injury were rated visually. Plots were machine harvested and yields converted to bushels per acre. Prices of the treatments are based on average price listed and are not intended as exact costs, rather to provide a relative difference between costs of the programs (Table 3). Costs include the application costs. Results:
VanGessel: Soybean Weed Control - 2
General comments: No herbicide injury was observed in either study. A hard rain that occurs just a soybeans are emerging can cause soil treated with Valor to splash onto the stems and leaves resulting in herbicide injury. However, the presence of crop residue (no-till system) and lack of rain prevented any risk of injury. A STS variety was used in these trials which eliminated any potential injury from Synchrony applied postemergence. Control of winter annual weeds was excellent with the paraquat treatment. Paraquat was applied as a separate procedure. Conventional soybean trial: Dual Magnum applied at planting was not adequate for full season grass control (Table 4). At 7 weeks after application, Dual provided 53 to 88% control depending on tank-mix partner. Lorox provided more grass suppression than Sencor, resulting in slightly higher level of grass control with Lorox combinations. This additional control (compared to Dual alone) was not commercially acceptable, but was noticeable in the trial, even through harvest. Of the treatments with only soil-applied herbicides (treatments 2 through 10), only two (treatments 6 and 10) provided acceptable weed control. These treatments were Canopy SP plus Dual Magnum or FirstRate plus Valor SX plus Dual Magnum. These treatments provided excellent control of all broadleaf weeds through harvest and fair to good for grass control. It was surprising to see such good control when precipitation was so limited. However, dry soil conditions early in the season prevented weed seed germination. Germination did not occur until rainfall, which also “activated” the soil-applied herbicides. All postemergence treatments (treatments 11 through 18) provided excellent control of all the broadleaf weeds present in the study (Table 4). The soil-applied application of Dual plus Lorox provided good to excellent grass control, eliminating the need for a postemergence application of Select. The practice of using soil-applied treatments may provide a broader application window for postemergence, but that was not investigated in this trial. Conversely, the addition of Select with either Reflex or Synchrony eliminated the benefit of the soil-applied herbicides in this trial. Synchrony plus Select provided excellent weed control and chemical cost was only $16/A. Weed density at Asbury Church field was quite sparse. Weed density was not great enough to impact yield. All treatments provided excellent control. Valor SX trial: All treatments provided excellent pigweed and lambsquarters control, except Sencor plus Dual (Table 5). Common ragweed control was excellent for all treatments containing Valor, except Valor at 2 oz plus Lorox and Dual. If Valor SX was tankmixed with another herbicide, or Valor rate was increased to 3 oz, common ragweed control was >86%.
VanGessel: Soybean Weed Control - 3
FirstRate plus Valor at 3 oz or Canopy plus Valor at 3 oz provided the highest level of control for all species present. However, both of these treatments were approximately $40/A (Table 2). The best method to determine the benefit of Valor SX is to compare Canopy plus Dual or Lorox plus Dual applied without Valor or with 2 or 3 oz/A of Valor. Canopy was good to excellent on all the species in this trial; while Lorox plus Dual was fair to good, depending on the species present (Figure 1). There was a step-wise increase in control with increasing rates of Valor. This was most notable with the Lorox plus Dual treatments. There was an additional $4.50/A cost of increasing Valor from 2 oz to 3 oz; however, there was also a significant increase in weed control. Sencor plus Dual provided only 67% control of common lambsquarters. However, the addition of 2 oz/A of Valor improved control to 100% (Table 5). This indicates Valor is very effective on common lambsquarters. Pigweed was also very sensitive to Valor, with control improving to 100% with the addition of 2 oz/A of Valor, compared to Sencor or Lorox alone. This was also observed at Asbury Church. Valor SX can improve overall weed control for many of the weeds found in Delaware. Valor SX at 2 oz/A is adequate when highly susceptible species such as pigweed or common lambsquarters are present. However, 3 oz/A is needed for control of other species such as common ragweed, common cocklebur, or morningglory. No yield differences were observed with any treatment. At UD-REC, the soybean stand was poor due to dry conditions at planting. As a result, yields were quite variable and it was difficult to detect significant differences. At Asbury Church site, the weed density was quite sparse and there was not enough weed pressure to impact yields.
VanGessel: Soybean Weed Control - 4
Table 1. Treatments for non-Roundup Ready™ soybeans trial. Trt No. 1 2 3 4
5
6
7 8 9
10
11
12
13
14
Treatment Name Untreated Check Sencor Dual II Magnum Lorox Dual II Magnum Sencor Lorox Dual II Magnum Boundary Premix ----s-metolachlor ----metribuzin Canopy SP Premix ----metribuzin ----chlorimuron Dual II Magnum Sencor Dual II Magnum Lorox Dual II Magnum Lorox Sencor Dual II Magnum Firstrate Valor SX Dual II Magnum Valor SX Synchrony XP Premix ----chlorimuron ----thifensulfuron Select Crop Oil Concentrate Dual II Magnum Synchrony XP Premix ----chlorimuron ----thifensulfuron Crop Oil Concentrate Dual II Magnum Lorox Synchrony XP Premix ----chlorimuron ----thifensulfuron Crop Oil Concentrate Synchrony XP Premix ----chlorimuron ----thifensulfuron Select
Product Rate
Product Rate Unit
Timing
4 1 0.5 1 4 0.5 1 1.25
oz wt/A pt/A lb/A pt/A oz wt/A lb/A pt/A pt/A
PRE PRE PRE PRE PRE PRE PRE PRE
5
oz wt/A
PRE
1 5 1 1 1 1 5 1 0.4 2 1 2 0.75
pt/A oz wt/A pt/A lb/A pt/A lb/A oz wt/A pt/A oz wt/A oz wt/A pt/A oz/A oz wt/A
PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE POST
6 1 1 0.75
fl oz/A qt/A pt/A oz wt/A
POST
1 1 0.5 0.75
1 0.75
6
Cost ($/A) 0.00 21.50 25.72 29.50
15.74
31.71
22.45 33.72 38.45
37.39
36.60
PRE POST
30.79
qt/A pt/A lb/A oz wt/A
PRE PRE POST
38.79
qt/A oz wt/A
POST
21.92
fl oz/A
POST
VanGessel: Soybean Weed Control - 5
15
16
17
18
Crop Oil Concentrate Valor SX Reflex Select Nonionic Surfactant Dual II Magnum Reflex Nonionic Surfactant Lorox Dual II Magnum Reflex Nonionic Surfactant Reflex Select Nonionic Surfactant
1 2 1 6 0.25 1 1 0.25 0.5 1 1 0.25 1 6 0.25
qt/A oz/A pt/A fl oz/A % v/v pt/A pt/A % v/v lb/A pt/A pt/A % v/v pt/A fl oz/A % v/v
PRE POST POST
43.73
PRE POST
37.92
PRE PRE POST
53.92
POST POST
29.05
VanGessel: Soybean Weed Control - 6
Table 2. Treatments to evaluate utility of Valor for Delaware soybean production. Trt No. 1 2
3
4
5
6
7
8
9
10 11 12
13
14
Treatment Name Untreated Check Valor SX Lorox Dual II Magnum Valor SX Sencor Dual II Magnum Valor SX Lorox Sencor Dual II Magnum Valor SX Boundary Premix ----s-metolachlor ----metribuzin Valor SX Canopy SP Premix ----metribuzin ----chlorimuron Dual II Magnum Valor SX Firstrate Dual II Magnum Valor SX Canopy SP Premix ----metribuzin ----chlorimuron Dual II Magnum Valor SX Lorox Dual II Magnum Lorox Dual II Magnum Sencor Dual II Magnum Lorox Sencor Dual II Magnum Boundary Premix ----s-metolachlor ----metribuzin Canopy SP Premix ----metribuzin ----chlorimuron Dual II Magnum
Product Rate
Product Rate Unit
2 1 1 2 4 1 2 0.5 4 1 2 1.25
oz/A lb/A pt/A oz/A oz wt/A pt/A oz/A lb/A oz wt/A pt/A oz/A pt/A
PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE
2 5
oz/A oz wt/A
PRE PRE
1 2 0.5 1 3 5
pt/A oz/A oz wt/A pt/A oz/A oz wt/A
PRE PRE PRE PRE PRE PRE
1 3 1 1 1 1 4 1 0.5 4 1 1.25
pt/A oz/A lb/A pt/A lb/A pt/A oz wt/A pt/A lb/A oz wt/A pt/A pt/A
PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE
5
oz wt/A
PRE
1
pt/A
PRE
Cost ($/A) 0.00 42.40
30.18
38.18
24.42
40.39
40.14
44.73
46.74
33.72 21.50 29.50
15.74
31.71
VanGessel: Soybean Weed Control - 7
Table 3. Estimated herbicide and application costs based on an average from various distributors. Costs will vary, but the intent is to provide relative costs of treatments. Herbicide / Product Boundary Premix Canopy SP Premix Dual II Magnum Firstrate Firstrate Lorox Lorox Reflex Select Sencor Sencor Synchrony XP Premix Valor SX Valor SX Crop Oil Concentrate Nonionic Surfactant Application cost
Rate 1.25 5 1 0.4 0.5 0.5 1 1 6 4 5 0.75 2 3 1 0.25
Rate unit pt/A oz wt/A pt/A oz wt/A oz wt/A lb/A lb/A pt/A fl oz/A oz wt/A oz wt/A oz wt/A oz/A oz/A qt/A % v/v
Cost ($/A) 9.74 13.99 11.72 10.99 13.74 8.00 16.00 12.50 8.85 3.78 4.73 4.77 8.68 13.02 2.30 1.70 6.00
VanGessel: Soybean Weed Control - 8
Table 4. Weed control and yield at UD-REC site for herbicide programs intended for conventional soybeans. Weed density was sparse at Asbury Church field. Visual ratings from 7/11/06 were 7 weeks after planting and/or 3 weeks after postemergence applications.
Trt. 1 2 3 4
5 6 7 8 9
10
11
12
Herbicide Untreated Check Sencor Dual II Magnum Lorox Dual II Magnum Sencor Lorox Dual II Magnum Boundary Canopy SP Dual II Magnum Sencor Dual II Magnum Lorox Dual II Magnum Lorox Sencor Dual II Magnum Firstrate Valor SX Dual II Magnum Valor SX Synchrony XP Select Crop Oil Conc. Dual II Magnum Synchrony XP Crop Oil Conc.
Product 4 1 0.5 1 4 0.5 1 1.25 5 1 5 1 1 1 1 5 1 0.4 2 1 2 0.75 6 1 1 0.75 1
rate
Timing
oz wt/A pt/A lb/A pt/A oz wt/A lb/A pt/A pt/A oz wt/A pt/A oz wt/A pt/A lb/A pt/A lb/A oz wt/A pt/A oz wt/A oz wt/A pt/A oz/A oz wt/A fl oz/A qt/A pt/A oz wt/A qt/A
PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE PRE POST POST PRE POST
PANDI
AMBEL
IPOSS
XANST
AMACH
GGGAN
ANNBR
Fall Panicum Control % 7/11/2006 0 f 62 de
Common Ragweed Control % 7/11/2006 0 e 23 d
Mornglry Species Control % 7/11/2006 0 e 20 cde
Common Cocklebr Control % 7/11/2006 0 c 50 b
Smooth Pigweed Control % 7/11/2006 0 d 70 bc
Annual Grasses Control % 10/13/2006 0 e 41 d
Annual Broadlvs Control % 10/13/2006 0 g 40 e
65
de
40
c
23
cd
68
de
50
bc
22
cd
100
63 75
de bcd
10 95
de a
10 96
de a
53
e
50
bc
37
73
cd
43
bc
78
bcd
57
88
abc
100
77
GLXMA Soybean Yield Bu/A 11/1/2006 16 f 23 ef
50
c
77
ab
40
e
31
b-e
a
100
a
73
ab
60
b
27
c-f
0 99
c a
80 99
ab a
50 71
bcd abc
50 100
d a
25 43
def a
bc
60
b
70
bc
42
cd
30
f
36
a-d
47
b
100
a
100
a
80
a
60
b
36
a-d
b
27
bcd
65
b
100
a
77
ab
55
c
33
a-e
97
a
93
a
100
a
100
a
89
a
100
a
33
a-e
a
100
a
100
a
100
a
100
a
96
a
100
a
34
a-d
bcd
100
a
100
a
100
a
100
a
78
ab
100
a
39
ab
13
Dual II Magnum Lorox Synchrony XP Crop Oil Conc. 14 Synchrony XP Select Crop Oil Conc. 15 Valor SX Reflex Select Nonionic Surfact. 16 Dual II Magnum Reflex Nonionic Surfact. 17 Lorox Dual II Magnum Reflex Nonionic Surfact. 18 Reflex Select Nonionic Surfact. LSD (P=.05) CV Treatment Prob(F)
1 0.5 0.75 1 0.75 6 1 2 1 6 0.25 1 1 0.25 0.5 1 1 0.25 1 6 0.25
pt/A lb/A oz wt/A qt/A oz wt/A fl oz/A qt/A oz/A pt/A fl oz/A % v/v pt/A pt/A % v/v lb/A pt/A pt/A % v/v pt/A fl oz/A % v/v
PRE PRE POST
90
abc
100
a
92
a
100
a
100
a
85
a
100
a
36
abc
POST POST
100
a
100
a
100
a
100
a
100
a
99
a
98.3
a
40
ab
PRE POST POST
100
a
100
a
99
a
100
a
100
a
100
a
100
a
43
a
PRE POST
78
bcd
100
a
100
a
100
a
100
a
87
a
100
a
36
a-d
PRE POST
93
ab
100
a
95
a
100
a
100
a
96
a
98
a
44
a
POST POST
100
a
100
a
100
a
100
a
100
a
97
a
97
a
40
ab
20 15 0.0001
15 13 0.0001
21 19 0.0001
29 21 0.0001
27 18 0.0001
29 24 0.0001
Means followed by same letter do not significantly differ (P=.05, LSD) Mean comparisons performed only when AOV Treatment P(F) is significant at mean comparison OSL.
VanGessel: Soybean Weed Control - 10
5 4 0.0001
12 20 0.0007
Table 5. Evaluation of Valor SX as a tankmix partner with soil-applied herbicides for weed control and yield. All treatments applied at planting and ratings were taken 7 weeks after planting.
Trt. 1 2
3
4
5 6
7
8
9
10
Herbicide Product Untreated Check Valor SX 2 Lorox 1 Dual II Magnum 1 Valor SX 2 Sencor 4 Dual II Magnum 1 Valor SX 2 Lorox 0.5 Sencor 4 Dual II Magnum 1 Valor SX 2 Boundary 1.25 Valor SX 2 Canopy SP 5 Dual II Magnum 1 Valor SX 2 Firstrate 0.5 Dual II Magnum 1 Valor SX 3 Canopy SP 5 Dual II Magnum 1 Valor SX 3 Lorox 1 Dual II Magnum 1 Lorox 1 Dual II Magnum 1
rate oz/A lb/A pt/A oz/A oz wt/A pt/A oz/A lb/A oz wt/A pt/A oz/A pt/A oz/A oz wt/A pt/A oz/A oz wt/A pt/A oz/A oz wt/A pt/A oz/A lb/A pt/A lb/A pt/A
AMACH Smooth Pigweed Control % 7/11/2006 0 c 100 a
AMBEL Common Ragweed Control % 7/11/2006 0 e 73 bcd
100
a
87
100
a
100
100
a
87
100
a
100
XANST Common Cocklebr Control % 7/11/2006 0 d 62 b
UD-REC CHEAL Common Lambqtrs Control % 7/11/2006 0 c 100 a
IPOSS Mornglry Species Control % 7/11/2006 0 g 62 bcd
Soybean Yield Bu/A 11/1/2006 25 a 30 a
Asbury Church Field AMACH Pigweed Species Soybean Control Yield % Bu/A 7/12/2006 11/1/2006 0 d 43 a 100 a 45 a
abc
30
c
100
a
55
de
35
a
100
a
43
a
a
35
c
100
a
57
cde
37
a
95
ab
45
a
abc
40
bc
100
a
62
bcd
38
a
100
a
43
a
100
a
93
a
100
a
88
ab
39
a
100
a
43
a
a
100
a
95
a
100
a
100
a
33
a
100
a
42
a
100
a
100
a
100
a
100
a
97
a
36
a
100
a
44
a
100
a
100
a
90
a
100
a
88
ab
46
a
100
a
44
a
95
ab
50
d
40
bc
100
a
33
ef
29.6
a
81
bc
42
a
VanGessel: Soybean Weed Control - 11
11
Sencor Dual II Magnum 12 Lorox Sencor Dual II Magnum 13 Boundary 14 Canopy SP Dual II Magnum LSD (P=.05) CV Treatment Prob(F)
4 1 0.5 4 1 1.25 5 1
oz wt/A pt/A lb/A oz wt/A pt/A pt/A oz wt/A pt/A
77
b
50
d
0
d
67
b
37
def
36
a
100
a
45
a
93
ab
65
cd
40
bc
100
a
33
ef
30
a
70
c
40
a
100 100
a a
20 95
e ab
20 87
cd a
87 100
ab a
23 83
fg abc
33 31
a a
95 100
ab a
42 42
a a
20 13 0.0001
25 20 0.0001
25 27 0.0001
27 18 0.0001
27 28 0.0001
17 29 0.6556
Means followed by same letter do not significantly differ (P=.05, LSD) Mean comparisons performed only when AOV Treatment P(F) is significant at mean comparison OSL.
VanGessel: Soybean Weed Control - 12
18 12 0.0001
5 7 0.6318
Figure 1. Weed control with the addition of Valor to other soil-applied herbicides.
100
Visual control (%)
90 80 70 60 50 40
Canopy (5 oz/A) + Dual (1 pt/A)
30 20 10 0
ry
Visual control (%)
ur
o gl
80
eb kl oc C
ng ni or
M
d ee
90
w ag R
100
70 60 50 40 30 20 10
Lorox (1 lb/A) + Dual (1 pt/A)
0
eb kl oc C ur
o gl
d ee
ng ni or
M
w ag R
ry No Valor Valor at 2 oz/A Valor at 3 oz/A
