Transcript Managing Insects Unique (?) to Southern Illinois

The soybean aphid in Illinois before 2003
 2000―Surprised like everyone else
 2001―Economic infestations occurred, but
they were not widespread. Populations within
fields tended to “crash” quickly.
 2002―Where did they go?
 2003 . . .
Evolution of the soybean aphid
problem in Illinois in 2003
 The problem in 2003 began in 2002
(some early indications of a potential problem)

Low-level densities of soybean aphid occurred in
2002―nothing economic

Very low numbers of the multicolored Asian lady
beetle in 2002

Noteworthy flight of winged aphids in the fall of
2002
Suction traps to capture flying aphids
9 locations
Data from suction traps, Fall 2002
Date
DeKalb
Monmouth
Urbana
Perry
Sep 20
0
17
0
2
Sep 27
2
80
71
284
Oct 4
38
62
13
133
Oct 11
7
3
4
9
Evolution of the soybean aphid
problem in Illinois in 2003
 Conditions in 2003 were favorable for the growth
and development of soybean aphids.

Very few predators allowed densities of aphids to
build early in the summer.

Cooler-than-usual temperatures favored
development of soybean aphid populations
(<85°F most of the time).

As many as 18 generations per season are
possible.
Evolution of the soybean aphid
problem in Illinois in 2003
 First winged soybean aphids found on April 23
(Dr. Dave Voegtlin, Champaign County)
 First soybean aphids found in soybeans on May 29
(Jeff Wessel, Joliet Junior College, Will County)
 Populations in northern IL through July, early Aug.
 Populations in central IL, early to mid-Aug.
 Populations in southern IL, mid- to late Aug.
Captures of soybean aphids in suction traps, Illinois, 2003
7/4
7/11
7/18
7/25
8/1
8/7
8/15
8/22
Freeport
0
21
176
112
787
1,912
1,810
1,347
DeKalb
0
1
131
940
6,755
4,890
286
264
MonMouth
0
0
1
59
71
569
1,403
---
Eureka
0
0
2
142
401
4,920
1,090
921
Urbana
0
0
0
2
9
163
602
1,131
Perry
0
0
0
4
8
232
1,560
---
BrnsTown
0
0
0
3
1
18
1,535
---
Dixon
Sprngs
0
0
0
1
0
0
31
2
The Soybean Aphid Outbreak
Illinois, 2003
 Primarily in northern




and central Illinois
Some economic
infestations in southern
Illinois
750,000 to 1 million
acres treated
$9 to $12 million in
treatment costs
~$45 million in yield
loss
Guidelines and treatment thresholds for
soybean aphids in July 2003
 Scout at least twice during late V early R
stages
 Apply an insecticide if . . .




Density of aphids is 25 or more per leaflet
Density of aphids increases from 1st to 2nd
sample
Percentage of alatoid nymphs is <50%
Soybean growth stage is R1 or R2
But what if the soybean growth stage was past R2?
Before 2003, thresholds were based on some research conducted at
Michigan State University in 2001.
Yield difference primarily due to pod number
Measure
Treated
Untreated
yield
2351 g
1414 g
% moisture
12.7%
12.0%
plant height
64.6 cm
54.2 cm
avg# pods/plant
17.7
14.0
avg# pods/main stem
14.6
11.6
nodes/main stem
11.3
10.7
weight per bean
0.136 g
0.131 g
Bean weight & # of beans not significantly different.
A review of soybean growth stages
 R1
Beginning bloom (open flower at any node)
 R2
Full bloom
(open flower at one of two uppermost nodes on
main stem)
 R3
Beginning pod (pod 3/16 inch long)
 R4
Full pod (pod 3/4 inch long)
 R5
Beginning seed (seed 1/8 inch long)
 R6
Full seed (green seed that fills pod cavity)
Treatment thresholds for
soybean aphids were adjusted in August
 25 or more aphids per leaflet
 250 aphids per plant at R1–R2
 1,000 aphids per plant at R3
 1,500 aphids per plant at R4–R5
Insecticides labeled for control
of soybean aphids
 Asana XL
 Chlorpyrifos




(Lorsban, Nufos)
Furadan
Mustang Max
Penncap-M
Warrior
How did soybean aphid infestations affect yield?
Insecticide applied
Not treated
McLean County
soybean field
Not treated
120 feet
check strip
Sprayed with
Warrior
at stage R2
1,000 to 2,000
aphids per plant
+ 10.75 bu/A
Soybean yields from people who reported
Fields treated for control of soybean aphids, 2003
Unknown
Before
Aug 1
1st Week
Aug
2nd
Week
Aug
39–48
40–50
28–56
42–48
42–49
43.5
45.2
49.2
44.6
45.3
29–39
38–41
21–40
29–37
34–43
Average
34.1
39.5
34.2
31.6
38.2
Range
9–10
7–9
7–26
7–18
5–11
9.4
7.8
14.9
13.2
7
Summary
Yield
(Treated)
Range
Average
Yield
(Not treated)
Difference in
Yield
Range
Average
3rd
Week
Aug
After
Aug 24
61.6
30.9
30.7
Information provided by Kevin Black,
Growmark, Inc., Bloomington, IL
 23 yield comparisons―Treated for aphid
control vs. not treated

Avg. treated yield


Avg. untreated yield


43.0 bu/A (range 27 to 59 bu/A)
34.6 bu/A (range 16.9 to 55 bu/A)
Avg. difference in yield, treated vs. not treated

8.4 bu/A (range -0.5 to 20.6 bu/A)
 Products used―Mustang Max, Warrior,
Furadan 4F, Lorsban 4E, Ambush 2E
Less-than-expected soybean yields
2003
 Soybean aphid infestations undoubtedly had
an impact, but . . .
 Weather conditions were not ideal for
optimum soybean yields, and
 Soybean diseases also caused yield
reductions


Charcoal rot
Root rots
Forecast for soybean aphids in 2004?
 Plenty of multicolored Asian lady beetles
present this fall . . .
 As well as numerous other predators this
summer . . .
 No significant aphid captures in suction traps
this fall . . .
 Weather next year?
Soybean aphids may be at low levels in 2004.
Research on the soybean aphid in
Illinois
 Biology, overwintering strategies, movement,
other hosts, biological control―David
Voegtlin
 Population dynamics, sampling―David
Onstad
 Resistant soybean cultivars―Glen Hartman
 Management―Kevin Steffey
Sampling for soybean aphids
(D. Onstad)
 Two counties, one township per county


Kendall County, Kendall Township
Champaign County, St. Joseph Township
 14 soybean fields randomly selected per
township


7 fields in norhtern half of township
7 fields in southern half of township
Sampling for soybean aphids
(D. Onstad)
 Fields sampled every 3 weeks from late June
or early July to early September
 Almost all fields sampled 4 times each year

Exceptions


St. Joseph Township―low numbers in 2002
Kendall Township―hail damage or insecticide
applications in 2003
Sampling for soybean aphids
(D. Onstad)
Two 50-m transects, at least 10 m apart
Samples every 2 m = 25 samples per transect
Field or
Township
July 5, 2001
July 1, 2002
June 23, 2003
July 25, 2001
July 22, 2002
July 14, 2003
Aug 17, 2001
Aug 18, 2002
Aug 4, 2003
Sep 6, 2001
No observation
Aug 25, 2003
2001 A
5.50
91.94
4.84
3.50
2001 B
0
0.82
0.94
5.28
St. Joseph 0.39
7.60
1.06
1.95
2002 A
0
0
0.19
---
2002 B
0
3.02
2.74
---
St. Joseph 0
0.23
0.33
---
2003 A
0
0.12
13.40
923.10
2003 B
0
0.02
26.04
6,064.00
St. Joseph 0
0.02
33.33
1,829.03
(from D. Onstad)
Field or
Township
July 5, 2001
July 2, 2002
June 24, 2003
July 26, 2001
July 23, 2002
July 16, 2003
Aug 15, 2001
Aug 12, 2002
Aug 5, 2003
Sep 4, 2001
Sep 6, 2002
Aug 29, 2003
2001 A
0.02
12.68
14.76
12.64
2001 B
16.24
57.26
14.56
2.22
Kendall
0.39
7.60
1.06
1.95
2002 A
0
1.66
15.84
78.38
2002 B
0.58
3.76
40.82
7.14
Kendall
0.19
5.09
34.37
20.94
2003 A
6.86
326.42
2,235.80
14.16
2003 B
9.30
109.70
191.06
3.38
Kendall
3.44
268.73
843.02
20.92
(from D. Onstad)
25
Data from 2001
19.8
Mean no. aphids per plant
20
16.5
15
1st
2nd
3rd
4th
10
7.6
6.1
5
0.4
1.1
2
1.6
0
St. Joseph
Kendall
(from D. Onstad)
40
Data from 2002
34.4
Mean no. aphids per plant
35
30
25
20.9
20
15
1st
2nd
3rd
4th
10
5.1
5
0
0.2
0.3
0.19
0
St. Joseph
Kendall
(from D. Onstad)
2000
1,829
1800
Data from 2003
Mean no. aphids per plant
1600
1400
1200
1000
1st
2nd
3rd
4th
843
800
600
400
269
200
0
0.02
33
21
3.4
0
St. Joseph
Kendall
(from D. Onstad)
2000
1800
1,829
Data from St. Joseph Township
Mean no. aphids per plant
1600
1400
1200
1st
2nd
3rd
4th
1000
800
600
400
200
0.4 7.6 1.1
2
0
0.2 0.3
0 0.02 33.3
0
2001
2002
2003
(from D. Onstad)
900
843
Data from Kendall Township
Mean no. aphids per plant
800
700
600
1st
2nd
3rd
4th
500
400
268.7
300
200
100
0.4 1.6 16.5 6
0.2 5.1
34.4 20.9
21
3.4
0
2001
2002
2003
(from D. Onstad)
Sampling for soybean aphids
Other findings (D. Onstad)
 Significant variability in densities of aphids among
fields
 No apparent effect of row spacing on aphid densities
 Probability of finding an infested field by mid-July
when mean density in the township is <2 aphids per
plant

50% in Kendall County, 11% in Champaign County
 Must sample at least 2 fields (Kendall Co.) or 14 fields
(Champaign Co.) for 75% chance of finding aphids in
1 field
 No relationship between aphid density and distance
from the field edge
Soybean aphid efficacy trial
Kendall County, IL, 2003
Product
Rate of
application
Aphids per trif.
Aphids per trif.
Aphids per trif.
21 DAT
14 DAT
7 DAT
Nufos 4E
2 pt
0.32 d
2.53 c
0.46 d
Nufos 4E
1 pt
4.62 c
10.48 b
0.75 d
Asana XL
8 oz
17.30 b
26.60 a
10.45 bc
Asana XL
6 oz
20.67 b
22.37 a
9.67 bc
Asana XL
7 oz
24.95 b
48.09 a
8.96 bc
0.025 lb a.i.
31.17 b
38.93 a
7.26 c
---
99.35 a
60.42 a
44.39 a
0.45 lb a.i.
104.58 a
43.03 a
15.97 ab
Warrior
Untreated
Lannate SP
Average of 48 aphids per trifoliate when treatments applied on July 23.
Soybean aphids per trifoliate, 21 DAT, Kendall Co., IL, 2003
120
104.6
99.4
100
80
60
40
e
at
n
La
n
ec
k
C
h
ar
ri
or
W
oz
A
sa
n
a
7
oz
A
sa
n
a
8
a
n
6
pt
A
sa
N
u
fo
s
1
pt
2
fo
s
u
N
oz
4.6
0.3
0
25
20.7
17.3
20
31.2
Soybean aphid efficacy trial
Pope County, IL, 2003
Rate of
application
14 DAT
7 DAT
2 pt
22.6 de
28.8 d
Asana XL
9.6 oz
47.6 cd
52.9 de
Warrior
3.84 oz
76.4 bc
57.5 cde
4 oz
91.0 b
97.4 bc
---
142.4 a
Product
Lorsban 4E
Mustang Max
Untreated
159.1 a
Trial established on R5 soybeans by Ron Hines, Senior Research Specialist, DSAC
Soybean aphid efficacy trial
Pope County, IL, 2003
Product
Rate of
application
Yield
(bu/A)--NS
Test Wt
(lb/bu)
2 pt
56.5
51.5 b
Asana XL
9.6 oz
54.3
51.9 ab
Warrior
3.84 oz
55.3
52.0 ab
4 oz
53.8
52.1 a
---
56.8
51.8 ab
Lorsban 4E
Mustang Max
Untreated
Trial established on R5 soybeans by Ron Hines, Senior Research Specialist, DSAC