Iowa State University, Northeast Research and Demonstration Farm
ISRF06-13
Evaluation of Soybean Fungicides in 2006
Leonor Leandro, assistant professor
XB Yang, professor
Alison Robertson, assistant professor
S.S. Navi, assistant scientist
John Shriver, research associate
Department of Plant Pathology
Introduction
Management of foliar diseases of soybean was
not a common practice in Iowa or in the
Midwest prior to the 2005 growing season.
However, with the introduction of Asian
soybean rust, caused by Phakopsora
pachyrhizhi, to the United States, fungicide
applications may become an additional but
necessary input in Midwestern soybean
production.
This report details the efficacy of fungicides,
registered for use against Asian soybean rust, on
fungal foliar diseases, and white mold, of
soybean during the 2006 growing season.
Material and Methods
Three fungicide trials comprising several
fungicides from BASF, Bayer, Dow, DuPont,
Cheminova, Schaeffer, Syngenta and Valent
were established at the ISU Northeast Research
Farm, Nashua, IA, in the 2006 season. Soybean
varieties Asgrow 2106RR in Trial 1, Pioneer
92M40RR in Trial 2, and Pioneer 92M91RR
in Trial 3 were planted (196,433 plants/acre) on
May 10, May 9, and April 28, 2006,
respectively, into no-till cornstalks. Each plot
consisted of six rows, with two rows unsprayed
border. Rows in plots were 30 in. apart. A
randomized complete block design with four
replications was used, with 23, 20, and 24
treatments in Trials 1, 2 and 3, respectively. All
initial treatments were applied at R3 (please see
details given below each table) and later
fungicide applications were applied as protocol
for individual treatments. Disease assessments
were made three and seven weeks after spraying
(Aug. 16 and Sept. 12, respectively). All
treatments were compared with an unsprayed
control. The middle four rows of each plot (10 ft
× 30 ft long) were mechanically harvested on
September 29, 2006 for Trials 1 and 2 and
October 6, 2006 for Trial 3. Plot yields (bu/ac),
the incidence (%), and severity (%) of foliar
diseases and white mold were recorded.
Results and Discussion
No disease was observed at the first evaluation
(Aug. 16). In the second evaluation (Sept. 12),
foliar diseases observed included downy mildew
and frogeye leaf spot. Foliar symptoms of
sudden death syndrome (SDS) also were
evident. Frogeye leaf spot and downy mildew
were observed in Trial 1, but not in Trial 2 and
3, while SDS was observed in Trial 2 and 3, but
not in Trial 1. White mold also was observed in
the three trials. The severity and incidence for
each disease are shown in Tables 1–3.
In Trial 1, downy mildew incidence was high
(75–100%), and severity ranged from 17 to 52%
among treatments, while frogeye leaf spot
incidence was moderate to high (57–100%) and
severity ranged from 17 to 45%. In Trial 2,
sudden death syndrome incidence was very low
(0–0.3%), but severity of diseased plants ranged
from 11 to 97%. A very low incidence of white
mold (0.02–2.44%) was recorded in all trials.
There were no differences among fungicide
treatments for any of the diseases observed,
except for the incidence of white mold in
Trial 2.
Yield of the plots ranged from 41 to 64, 55 to
67, and 68 to 77 bushels/acre, in Trials 1, 2, and
3, respectively. Treatment differences in yield
were observed in Trial 1 between the unsprayed
check and several sprayed plots, but no
Iowa State University, Northeast Research and Demonstration Farm
differences in yield were found for yield in
Trials 2 or 3.
It is anticipated that the experiment will be
repeated in the coming seasons, or at least until
we know if Asian soybean rust will be a
frequent production risk to Iowa soybean
growers.
ISRF06-13
Acknowledgments
We would like to thank Asgrow Seed Company,
BASF Corporation, Bayer CropScience,
Cheminova Inc., Dow AgroSciences, Dupont,
Schaeffer Oil, Monsanto Company, Pioneer HiBred International, Syngenta Crop Protection,
and Valent USA for product support for this
study.
Iowa State University, Northeast Research and Demonstration Farm
ISRF06-13
Table 1. Evaluation of fungicides, registered for use against Asian soybean rust, against soybean foliar diseases, and white mold during 2006 at Nashua, 7 weeks after treatment application
(assessment date Sept. 12, 2006).
Downy mildew
Frogeye leaf spot
Sudden death syndrome
White mold
Application
Incidence
Severity
Incidence
Severity
Incidence
Severity
Incidence
Severity
rate (oz/ac)
Trmt
Trial 1
Yield (bu/ac)4
(%)
(%)
(%)
(%)
(%)
(%)
(%)
(%)
1
Untreated check
0
88.8
43.8
78.8
27.5
0
0
0.43
62
52.49 cde
2
Punch1
4
100.0
50.0
70.0
30.0
0
0
0.02
25
44.76 ef
3
Punch1
3
87.5
30.0
100.0
37.5
0
0
0.37
75
45.25 ef
4
Punch1
4
100.0
35.0
57.5
17.5
0
0
0.08
25
52.15 cde
5
Punch
1
3
87.5
27.5
87.5
37.5
0
0
0.20
100
51.67 de
6
Punch1
4
100.0
35.0
77.5
18.8
0
0
0.35
75
45.87 ef
7
Charisma1
10
85.0
27.5
100.0
45.0
0
0
0.17
25
41.41 f
8
1
Uppercut
4
85.0
17.5
100.0
37.5
0
0
0.33
75
44.12 ef
9
10
Quadris1
Headline1
0
0
0
0
0.46
0.30
75
75
60.88 abcd
57.43 abcd
0
0
0.76
50
61.31 abc
0
0
0.35
75
59.77 abcd
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.41
0.11
0.68
0.30
0.48
0.31
0.28
0.69
0.37
0.17
0.07
50
25
50
75
75
50
50
75
75
50
50
60.50 abcd
64.25 a
55.44 abcd
56.88 abcd
62.25 ab
57.63 abcd
58.66 abcd
59.25 abcd
52.94 bcde
56.87 abcd
55.46 abcd
6.2
100.0
25.0
100.0
35.0
6.2
75.0
35.0
80.0
30.0
5.5+4+0.25
1
11
Quadris+Alto+NIS
87.5
30.0
100.0
32.5
% v/v
5.5+4+0.25
1,3
12
Quadris+Alto+NIS
87.5
42.5
100.0
22.5
% v/v
1,3
13
Quilt+COC
14+1%v/v
75.0
27.5
100.0
35.0
14
Quadris+COC1
6+1%v/v
100.0
45.0
100.0
32.5
15
Topguard1
7
75.0
25.0
80.0
33.8
16
Topguard1
14
100.0
52.5
100.0
25.0
17
Topguard1,2
7
90.0
35.0
90.0
25.0
18
Topguard+NIS1
7+0.25%v/v
75.0
40.0
80.0
30.0
1
19
Topguard+Headline
7+6
100.0
42.5
100.0
30.0
20
Spectra1
4
100.0
45.0
77.5
32.5
21
Headline1
6
100.0
40.0
76.3
23.8
22
Headline+Wet Sol 991
6+4
100.0
42.5
100.0
35.0
23
Headline+Wet Sol 991
3+4
90.0
45.0
100.0
25.0
1
Treatments 2–23 applied on R3 growth stage soybeans on July 24, 2006.
2
Treatments 17 received second application at R3 + 21-day growth stage on August 15, 2006.
3
Treatments 12 and 13 received second application at R3 + 28-day growth stage on August 21, 2006.
4
Means sharing a common letter do not differ significantly (P<0.05), no treatment differences found if no letters present.
Iowa State University, Northeast Research and Demonstration Farm
ISRF06-13
Table 2. Evaluation of fungicides, registered for use against Asian soybean rust, against soybean foliar diseases, and white mold during 2006 at Nashua, 7 weeks after treatment application
(assessment date Sept. 12, 2006).
Downy
Downy
Frogeye leaf
Frogeye
White
White
mildew
mildew
spot
leaf spot
SDS
SDS
mold
mold
incidence
severity
incidence
severity
incidence
severity
incidence
severity
Application rate
(%)
(%)
Trmt
Trial 2
(oz/ac)
(%)
(%)
(%)
(%)
(%)
(%)
Yield (bu/ac)4
25
Untreated check
0
0
0
0
0
0.02
12.5
2.44 a
100
63.23
Laredo+NIS1 Laredo+
7+0.125%v/v,
26
0
0
0
0
0.30
67.5
0.83 b
100
64.71
Headline+NIS1,2
5+6+0.125v/v
Enable+COC1 Enable,
7+1%v/v,
27
0
0
0
0
0.15
67.5
1.44 ab
100
58.24
Headline+COC1,2
5+6+1%v/v
2.5 lbs+
Dithane+NIS1
0.125%v/v,
28
0
0
0
0
0.08
25.0
0.96 b
100
59.07
Dithane+NIS1,3
2.5 lbs+
0.125%v/v
2.5lbs +
29
Dithane+NIS3
0
0
0
0
0.15
75.0
1.70 ab
100
59.80
0.125%v/v
1
30
Domark
4
0
0
0
0
0.08
50.0
1.96 ab
100
59.20
31
Domark+Quadris1
3+3
0
0
0
0
0.06
50.0
1.48 ab
100
59.93
32
Phenix1
5
0
0
0
0
0.04
25.0
1.66 ab
100
60.28
33
LEM 171,3
2
0
0
0
0
0.08
25.0
1.37 ab
100
56.18
34
LEM 171,3
3.5
0
0
0
0
0.04
25.0
1.94 ab
100
58.91
35
LEM 171,3
5
0
0
0
0
0.06
25.0
2.18 ab
100
55.35
36
LEM 17+Punch1,3
2+3.3
0
0
0
0
0.17
50.0
1.88 ab
100
62.58
37
LEM 17+Folicur1,3
2+2
0
0
0
0
0.07
50.0
0.83 b
100
58.42
38
Punch1,3
4
0
0
0
0
0.08
25.0
1.65 ab
100
58.17
39
LEM 171
5
0
0
0
0
0.06
25.0
1.63 ab
100
57.56
40
Folicur1,3
4
0
0
0
0
0.00
0.0
2.06 ab
100
59.59
41
Absolute1,3
5
0
0
0
0
0.11
75.0
0.85 b
100
67.09
42
Stratego+Induce1,3
10+0.125%v/v
0
0
0
0
0.09
50.0
1.16 ab
100
66.91
43
Headline1,3
6
0
0
0
0
0.19
97.5
1.20 ab
100
63.33
44
Quilt1,3
14
0
0
0
0
0.17
72.5
1.02 ab
100
62.63
1
Treatments 26–28 and 30–44 applied on R3 growth stage soybeans on July 25, 2006.
2
Treatments 26 and 27 received second application at R3 + 21-day growth stage on August 15, 2006.
3
Treatments 28 and 29 and 33–38 and 40–44 received second application at R4–R5 growth stage on August 8, 2006.
4
Means sharing a common letter do not differ significantly (P<0.05), no treatment differences found if no letters present.
Iowa State University, Northeast Research and Demonstration Farm
ISRF06-13
Table 3. Evaluation of fungicides, registered for use against Asian soybean rust, against soybean foliar diseases, and white mold during 2006 at Nashua, 7 weeks after treatment application
(assessment date Sept. 12, 2006).
Downy
Downy
Frogeye leaf
White
mildew
mildew
spot
Frogeye leaf
SDS
SDS
White mold
mold
incidence
severity
incidence
spot severity
incidence
severity
incidence
severity
Application rate
Yield
(%)
(%)
(%)
(%)
Trmt
Trial 3
(oz/ac)
(%)
(%)
(%)
(%)
(bu/ac)4
47 Headline+Caramba1
4.4+7.7
0
0
0
0
0.03
11.3
1.15
81.3
74.08
48 Headline+Caramba1
3.6+6.1
0
0
0
0
0
0
0.83
87.5
69.90
49 Headline+NIS1
6+0.25% v/v
0
0
0
0
0
0
0.42
87.5
74.60
Headline+NIS1
50
6+0.25% v/v, 8
0
0
0
0
0
0
0.89
87.5
69.55
Caramba1,2
Headline+NIS1
6+0.25% v/v,
51
0
0
0
0
0.08
18.8
1.16
90.0
71.88
Headline+Caramba1.2
3.6+6.1
52 Headline+Folicur1
4.7+3.2
0
0
0
0
0
0
1.10
87.5
73.33
53 Headline+Folicur1
3.6+2.4
0
0
0
0
0
0
0.64
90.0
73.85
54 Quadris+NIS1
6.2+0.125% v/v
0
0
0
0
0
0
0.42
65.0
72.73
55 Headline+NIS1
6+0.125%v/v
0
0
0
0
0
0
1.66
85.0
72.38
56 Folicur1
4
0
0
0
0
0
0
1.31
87.5
72.55
57 Domark1
5
0
0
0
0
0
0
1.70
87.5
72.25
58 Headline SBR1
7.8
0
0
0
0
0
0
1.33
87.5
75.63
59 Stratego1
7
0
0
0
0
0
0
1.77
85.0
72.20
60 Quilt1
14
0
0
0
0
0.02
15.0
1.95
85.0
72.25
Headline+Caramba
61
4.4 + 7.7
0
0
0
0
0.04
17.5
1.54
87.5
74.78
1
(12.1)
1
62 Caramba
8.2
0
0
0
0
0
0
1.33
85.0
71.03
63 Laredo1
7
0
0
0
0
0
0
0.94
87.5
68.50
64 Gem+Folicur1
2.88 + 3.1
0
0
0
0
0
0
1.64
87.5
72.23
65 Headline1
6
0
0
0
0
0
0
0.71
92.5
75.60
Headline+Caramba
66
4.4 + 7.7
0
0
0
0
0
0
1.83
88.8
73.53
(12.1) 1
Headline+Caramba
67
4.4+7.7/8.2
0
0
0
0
0
0
0.75
92.5
77.05
(12.1) 1 /Caramba1,2
Headline/Caramba
4.4+7.7/
68 (12.1) 1 Headline/
0
0
0
0
0
0
0.73
87.5
73.53
3.1+6.1
Caramba (9.7) 1,2
Headline1/Headline +
69
6/3.1 + 6.1
0
0
0
0
0
0
0.69
67.5
74.23
Caramba (9.7) 1,2
70 Untreated check
0
0
0
0
0
0
0
1.33
67.5
71.69
1
Treatments 47–69 applied on R3 growth stage soybeans on July 26, 2006.
2
Treatments 50 and 51 and 67–69 received second application at R3 + 21-day growth stage on August 15, 2006.
3
No significant differences were found among treatments.