Efficacy of Registered and Experimental Insecticides to Control Corn Rootworm Larvae at Three Locations in Illinois, 2000
John T. Shaw, Michael E. Gray, and Kevin L. Steffey

Summary

Plot Information and Methods

Locations

Corn rootworm insecticide trials were established at the following locations:

1. Northern Illinois Agronomy Research Center, DeKalb, Illinois

2. Northwestern Illinois Agricultural Research and Demonstration Center, Monmouth, Illinois

3. University of Illinois, Crop Sciences Research & Education Center, Field EG-200 NE, Urbana, Illinois.

Plot Size

Each insecticide was applied to one row (40 feet long). Alleys (20 feet wide) were established between all replications at each location.

Experimental Design

A randomized complete block with four replications was utilized as the experimental design at all locations. Two untreated control plots were included within each replication. Data collected from the untreated control plots were averaged for the analysis of variance (ANOVA).

Planting Dates and Agronomic Factors

See Table 4.1.

Pre-treatment Population

The Monmouth and DeKalb locations were planted (1999) as trap crops (late-planted corn and pumpkins) in an effort to enhance rootworm oviposition and increase larval densities in 2000. At the Urbana location a late-planted cornfield was sprayed with a mixture of buffalo gourd root powder and water to increase the level of larval injury in 2000.

Method of Application for Granules at Planting Time

Granular insecticides were applied at planting and metered through computer controlled SmartBox (SBX) granular applicators or NobleŽ units mounted on each row of an ALMACOŽ four-row precision planter. Insecticides were applied in-furrow or in a 7-in. band ahead of the firming wheels on the planter. Spring tines mounted behind each planter unit were used to incorporate the insecticide. All rates are specified as lb. (AI)/acre based on a 30-inch row spacing.

Method of Application for Liquids at Planting Time

Regent 4SC, Force WF2829 30CS and Force WF 2899 25CS were delivered in-furrow at planting through microtubes calibrated to deliver 2.1 gpa at 30 psi at a speed of 3.0 mph at all three locations. Capture 2EC, Force WF2829 30CS, Warrior T 1SC and Force WF2899 25CS were applied through a single 8003 (flat fan) nozzle in-furrow or as a band and calibrated to deliver 4.9 gpa at 21 psi at a speed of 3.0 mph.

Method of Application for Liquids at Rootworm Egg Hatch

At the Urbana location only Furadan 4F insecticide treatment was applied on May 26, with a CO₂ backpack sprayer with two 8002VS nozzles directed on either side of a single row and calibrated to deliver 20.4 gpa at 20 psi.

Seed Treatments

All seed treatments were applied to NK 58D-1 seed by the respective company. This same seed variety was utilized for all treatments in all three locations.

Stand Counts

Stand count data (Table 4.2) were determined by recording the number of plants per 0.001 acre (17.4 linear feet of row).

Phytotoxicity

Symptoms of phytotoxicity were not observed at the three locations for any of the insecticide treatments.

Other Observations

No major handling or calibration problems occurred with any of the insecticides.

Post-Treatment Evaluation of Rootworm Injury

Five plants per treatment per replication were dug, washed, and evaluated for rootworm injury. The root-rating system used was the Iowa State University root-rating scale described by Hills and Peters (1971):

1. No visible damage or only a few minor feeding scars

2. Some roots with feeding scars but none eaten off to within 1.5 inches of the plant

3. Several roots eaten off to within 1.5 inches of the plant but never the equivalent of an entire node of roots destroyed

4. One node of roots destroyed or the equivalent

5. Two nodes of roots destroyed or the equivalent

6. Three or more nodes of roots destroyed.

Root rating data are presented in Table 4.3. Consistency ratings also are provided in Table 4.4 and are based upon the percentage of the total number of roots examined for each treatment that had root ratings less than 4.0.

Weather Information

See Appendix A, Table A.1 and Table A.2, Table A.4 and Table A.5, Table A.6 and Table A.7, for Urbana, DeKalb, and Monmouth, respectively.

Statistical Analysis

Data were analyzed with the Agriculture Research Manager (ARM) version 6.1.6, from Gylling Data Management, Inc.(GDM). Means were separated by Duncan's New MRT test (P=0.05).

Results and Discussion

Stand counts were taken at DeKalb and Urbana (Table 4.2). The number of plants per 0.001 acre (17.4 linear feet of row) was not statistically different among the treatments in DeKalb. At the Urbana location, significantly fewer plants were observed in plots treated with the seed treatment (EX-5) and Fortress 5G (0.19 lb. AI/acre) applied in-furrow.

Average root injury ratings in untreated control plots at DeKalb, Monmouth, and Urbana were 4.18, 4.14, and 5.03, respectively. This level of root injury in control plots represents moderate pressure (a single node of roots destroyed) for DeKalb and Monmouth. Larval injury at Urbana was severe (two nodes of roots destroyed) in the control plots. Although the registered soil insecticides [Aztec 2.1G (band), Counter 20CR (band), Force 3G (band and furrow), Fortress 5G (furrow), Lorsban 15G (band)], provided adequate root protection at each of the locations, the seed treatments ProShield and Gaucho (0.6, 1.0 and 1.3 mg per seed rates) did not keep root injury below the economic injury index of 3.0. Consistency ratings of the seed treatments revealed the very erratic root protection afforded by these products.

Several soil insecticides were applied as liquid formulations and included Capture 2EC, Furadan 4F, and Regent 4SC. Root injury in plots treated with Capture 2EC was kept below the economic injury index (3.0) at Monmouth and Urbana. However, root injury at DeKalb exceeded this level (3.65) in plots treated with Capture 2EC at the 0.09 lb. (AI)/acre rate. Curiously, when Capture 2EC was applied at a lower rate (0.08 lb. (AI)/acre), roots averaged 2.85 in these plots. Consistency ratings (Table 4.4) for this product, particularly at DeKalb, suggests more data are required before we can fully assess the long-term reliability of this product. Root injury ratings were kept below the economic injury index in plots treated with Regent 4SC as a band application. More root injury occurred in plots treated with microtube applications of Regent 4SC in DeKalb and Monmouth, 3.0 and 3.25, respectively. At Urbana, microtube applications of Regent 4SC provided very good root protection.

Furadan 4F was applied only at the Urbana site and failed to provide adequate root protection (average root rating of 3.80). Consistency data revealed that 67% of the roots in plots treated with Furadan 4F exceeded a root injury rating of 4.0.

References Cited

Hills, T.M., and D.C. Peters. 1971. A method of evaluating post-plant insecticide treatments for control of western corn rootworm larvae. J. Econ Entomol. 64: 764-765.

Table 4.1: Agronomic factors and evaluation dates at three locations to test corn rootworm soil insecticides, Illinois, 2000

Variables

DeKalb

Monmouth

Urbana

Planting date

May 17, 2000

May 16, 2000

April 28, 2000

Hybrid

NK58 D-1

NK58 D-1

NK58 D-1

Plant population

28,500 seeds per acre

28,500 seeds per acre

28,500 seeds per acre

Row spacing

30 inches

30 inches

30 inches

Soil condition (top 2-3 inches)

Moist

Moist

Dry

Soil temperature (4-inch level)

60°F

63°F

61°F

Air temperature

70°F

70°F

65°F

Wind

8 - 10 mph

5 - 7 mph

2-4 mph

Previous crop

trap crop - corn + pumpkins (1999)

trap crop - corn + pumpkins (1999)

trap crop - corn (1999)

Soil insecticides

None

None

None

Herbicides

Degree (pre-emergence)
Balance, Aatrex (post-emergence)

Degree, Atrazine (pre-emergence)
Basagran, UAN (post-emergence)

Fertilizer

Anhybrous 180 lbs.

N 160 lb/Acre

Fall tillage

Coulter Chisel

Chisel plow

Spring tillage

Mulch finisher twice

Dyna-drive

Cultivation date

June 8

None

Evaluation dates:

May 23, 2000

Stand Counts

June 1

---

June 5

Root ratings

July 25

July 24

July 13

Table 4.2 Mean stand counts for corn rootworm soil insecticides at two locations, Illinois, 2000

Treatment

Rate¹

Placement

Stand Counts²

DeKalb

Urbana

Capture 2EC

0.090

band

23.75

abc

27.00

a-d

Capture 2EC

0.080

band

27.75

ab

25.75

a-d

Furadan 4F

1.000

broadcast

24.50

abc

25.25

a-d

Aztec 2.1G

0.150

band

21.75

bc

24.50

a-d

Aztec BD 2.1G

0.150

band

26.00

ab

25.00

a-d

Aztec BD 2.1G

0.110

band

26.00

ab

25.75

a-d

Force 3G

0.130

furrow

24.75

abc

23.25

a-d

Force 3G

0.130

band

22.50

bc

29.00

a

EX-4

seed treatment

29.00

a

24.75

a-d

EX-5

seed treatment

26.25

ab

21.50

d

EX-6

seed treatment

24.75

abc

22.25

bcd

Force WF2829 30CS

0.080

band

25.00

ab

26.75

a-d

Force WF2829 30CS

0.120

band

25.00

ab

26.75

a-d

Force WF2829 30CS

0.160

band

22.00

bc

27.75

a-d

Force WF2829 30CS

0.080

microtube

23.00

abc

27.50

a-d

Force WF2829 30CS

0.120

microtube

21.75

bc

25.75

a-d

Force WF2829 30CS

0.160

microtube

25.75

ab

26.75

a-d

Regent 4SC

0.130

microtube

23.33

abc

23.50

a-d

Regent 4SC

0.130

band

23.50

abc

26.50

a-d

Lorsban 15G

1.300

band

24.75

abc

26.00

a-d

Lorsban 15G

1.300

furrow

23.00

abc

22.75

a-d

ProShield

seed treatment

26.00

ab

25.75

a-d

Pilot 15G

1.300

band

23.00

abc

25.00

a-d

CRAG-00011 20G

1.000

band

26.25

ab

26.50

a-d

CRAG-00011 20G

0.750

band

23.00

abc

26.50

a-d

CRAG-00011 20G

0.500

band

23.67

abc

25.50

a-d

NuFos 15G

1.300

band

26.50

ab

24.75

a-d

Counter 20CR

1.300

band

23.75

abc

24.25

a-d

Warrior T 1CS

0.030

band

26.50

ab

23.50

a-d

Warrior T 1CS

0.060

band

25.50

ab

28.25

abc

Warrior T 1CS

0.090

band

24.75

abc

23.75

a-d

Force WF2899 25CS

0.125

band

24.75

abc

22.25

bcd

Force WF2899 25CS

0.125

microtube

21.75

bc

29.25

a

Fortress 5G

0.160

band

22.25

bc

25.25

a-d

Fortress 5G

0.160

furrow

26.50

ab

26.50

a-d

Gaucho

1.300

seed treatment

23.50

abc

23.75

a-d

Gaucho

1.000

seed treatment

22.00

bc

24.75

a-d

Gaucho

0.600

seed treatment

25.00

ab

26.50

a-d

Fortress 5G

0.190

furrow

25.33

ab

22.00

cd

Control

23.50

abc

28.75

ab

¹ Rates are specified as lb (AI)/acre, except for seed treatments which are expressed as mg/seed.
² Means in a column followed by the same letter are not significantly different (P=0.05; Duncan's New MRT).

Table 4.3 Mean root ratings for corn rootworm soil insecticides at three locations, Illinois, 2000

Treatment

Rate¹

Placement

Root Ratings²

DeKalb

Monmouth

Urbana

Capture 2EC

0.090

band

3.65

a-f

2.25

e-h

2.60

f-l

Capture 2EC

0.080

band

2.85

d-m

2.50

efg

2.85

d-l

Furadan 4F

1.000

broadcast

---

---

3.80

bcd

Aztec 2.1G

0.150

band

1.85

m

1.60

gh

2.60

f-l

Aztec BD 2.1G

0.150

band

1.95

lm

1.65

gh

2.00

l

Aztec BD 2.1G

0.110

band

2.05

klm

1.75

gh

2.89

d-l

Force 3G

0.130

furrow

2.20

j-m

1.67

gh

2.30

i-l

Force 3G

0.130

band

1.85

m

2.80

d-g

2.05

kl

EX-4

seed treatment

3.47

a-h

4.25

a

3.20

b-j

EX-5

seed treatment

3.49

a-h

2.20

e-h

2.90

d-l

EX-6

seed treatment

3.70

a-e

2.60

d-g

2.95

d-l

Force WF2829 30CS

0.080

band

2.45

h-m

2.35

e-h

2.73

e-l

Force WF2829 30CS

0.120

band

2.10

klm

2.05

e-h

2.28

i-l

Force WF2829 30CS

0.160

band

2.06

klm

3.25

a-e

2.53

g-l

Force WF2829 30CS

0.080

microtube

2.95

c-l

3.00

c-f

2.45

h-l

Force WF2829 30CS

0.120

microtube

2.60

f-m

2.60

d-g

3.05

c-l

Force WF2829 30CS

0.160

microtube

2.73

e-m

2.41

e-h

2.45

h-l

Regent 4SC

0.130

microtube

3.00

c-l

3.25

a-e

2.45

h-l

Regent 4SC

0.130

band

2.55

g-m

2.50

d-g

2.80

d-l

Lorsban 15G

1.300

band

2.50

g-m

2.65

d-g

2.13

kl

Lorsban 15G

1.300

furrow

3.57

a-g

1.95

fgh

2.20

jkl

ProShield

seed treatment

4.35

a

3.75

a-d

3.55

b-g

Pilot 15G

1.300

band

2.70

e-m

2.20

e-h

2.05

kl

CRAG-00011 20G

1.000

band

3.25

b-j

2.10

e-h

2.35

i-l

CRAG-00011 20G

0.750

band

2.60

f-m

2.20

e-h

2.63

e-l

CRAG-00011 20G

0.500

band

2.53

g-m

3.10

a-f

3.41

b-h

NuFos 15G

1.300

band

2.25

i-m

2.20

e-h

3.25

b-i

Counter 20CR

1.300

band

2.67

e-m

1.20

h

2.14

kl

Warrior T 1CS

0.030

band

3.85

a-d

2.55

d-g

3.45

b-h

Warrior T 1CS

0.060

band

3.30

b-i

4.20

ab

3.06

c-k

Warrior T 1CS

0.090

band

3.90

a-d

3.05

b-f

2.71

e-l

Force WF2899 25CS

0.125

band

2.15

klm

2.40

e-h

3.00

c-l

Force WF2899 25CS

0.125

microtube

2.70

e-m

2.10

e-h

2.60

f-l

Fortress 5G

0.160

band

3.05

c-k

---

4.09

b

Fortress 5G

0.160

furrow

3.25

b-j

2.15

e-h

2.10

kl

Gaucho

1.300

seed treatment

3.90

a-d

3.20

a-f

3.65

b-e

Gaucho

1.000

seed treatment

3.95

abc

3.00

c-f

3.60

b-f

Gaucho

0.600

seed treatment

4.35

a

3.25

a-e

4.00

bc

Fortress 5G

0.190

furrow

2.80

e-m

2.15

e-h

2.50

h-l

Fortress 5G

0.220

furrow

2.35

i-m

2.65

d-g

2.20

jkl

Control

4.18

ab

4.14

abc

5.03

a

¹ Rates are specified as lb (AI)/acre, except for seed treatments which are expressed as mg/seed.
² Means in a column followed by the same letter are not significantly different (P=0.05; Duncan's New MRT).

Table 4.4 Mean consistency ratings for corn rootworm soil insecticides at three locations, Illinois, 2000

Treatment

Rate¹

Placement

Consistency Ratings^2,3

DeKalb

Monmouth

Urbana

Capture 2EC

0.090

band

40

90

80

Capture 2EC

0.080

band

80

90

80

Furadan 4F

1.000

broadcast

---

---

33

Aztec 2.1G

0.150

band

100

100

100

Aztec BD 2.1G

0.150

band

100

100

100

Aztec BD 2.1G

0.110

band

100

100

79

Force 3G

0.130

furrow

95

100

95

Force 3G

0.130

band

100

80

100

EX-4

seed treatment

60

65

65

EX-5

seed treatment

58

95

80

EX-6

seed treatment

30

90

75

Force WF2829 30CS

0.080

band

80

85

87

Force WF2829 30CS

0.120

band

95

95

100

Force WF2829 30CS

0.160

band

100

65

93

Force WF2829 30CS

0.080

microtube

70

65

90

Force WF2829 30CS

0.120

microtube

85

80

75

Force WF2829 30CS

0.160

microtube

80

79

100

Regent 4SC

0.130

microtube

80

65

100

Regent 4SC

0.130

band

100

75

67

Lorsban 15G

1.300

band

90

80

100

Lorsban 15G

1.300

furrow

57

100

100

ProShield

seed treatment

20

35

50

Pilot 15G

1.300

band

90

95

100

CRAG-00011 20G

1.000

band

55

100

95

CRAG-00011 20G

0.750

band

85

100

95

CRAG-00011 20G

0.500

band

93

70

59

NuFos 15G

1.300

band

90

100

45

Counter 20CR

1.300

band

73

100

95

Warrior T 1CS

0.030

band

35

85

65

Warrior T 1CS

0.060

band

50

25

58

Warrior T 1CS

0.090

band

40

70

89

Force WF2899 25CS

0.125

band

100

85

75

Force WF2899 25CS

0.125

microtube

70

100

90

Fortress 5G

0.160

band

60

---

26

Fortress 5G

0.160

furrow

55

100

100

Gaucho

1.300

seed treatment

35

50

40

Gaucho

1.000

seed treatment

25

65

50

Gaucho

0.600

seed treatment

25

60

32

Fortress 5G

0.190

furrow

87

100

95

Fortress 5G

0.220

furrow

95

80

100

Control

30

30

0

¹ Rates are specified as lb (AI)/acre, except for seed treatments which are expressed as mg/seed.
² Means in a column followed by the same letter are not significantly different (P=0.05; Duncan's New MRT).
³ Consistency rating is the percentage of the total number of roots examined with a root rating less than 4.0.

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