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Efficacy
of Registered and Experimental Insecticides
for Control of Second- Generation European
Corn Borer in Illinois, 2000 |
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John T. Shaw,
Kevin L. Steffey, and Michael E. Gray
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Summary |
A
trial was established at the University
of Illinois Crop Science Research &
Education Center to compare the effectiveness
of registered and experimental insecticides
for control of second-generation European
corn borer. Survival of second-generation
ECB larvae was quite high; with at least
52% of the plants in all plots having
cavities. However, Warrior T 1SC, Tracer
2SC at 0.015 lb (AI)/acre, and Tracer
2SC at 0.031 lb (AI)/acre were significantly
better for most parameters measured
than the untreated control. |
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Plot Information and Methods
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Location
University of Illinois Crop Sciences
Research & Education Center, Field
EG-400 NW, Urbana, Illinois.
Plot Size
Four rows (30-inrow spacing) ´
50 ft for each treatment in each replication,
with 20-ft alleys between each replication.
Treatments were applied to the center
two rows of each plot leaving two untreated
rows between each plot.
Experimental
Design
Randomized complete block with four
replications with two untreated control
plots in each replication. Data collected
from the untreated control plots were
averaged for the ANOVA.
Planting
Dates and Agronomic Factors
Refer to Table 7.1.
Weather
Information
See Appendix A, Tables
A.3.
Manual infestation
of ECB
Manual infestation of ECB larvae to
simulate the second-generation were
made at corn anthesis (V18 - VT corn
stage: Ritchie et al. 1993) on August
16 and again on August 18. Five egg
masses (black-head stage) were placed
ino the first leaf axils both above
and below the ear nodes on 10 consecutive
plants in each of the middle two rows
of a four-row plot.
Pre-Treatment
Densities of ECB
On August 21, just before insecticide
application, 20 infested plants were
examined for surviving ECB larva. An
average of 4.2 first and second instars
per plant was recorded. The percent
of infestation from the first generation
(natural infestation) was negligible
and did not influence the counts for
the second generation.
Method
of Insecticide Application
All insecticide treatments were applied
with a modified John Deere 6000 high-clearance
vehicle (HCV). Liquid insecticides were
applied on August 21, three days after
the second manual infestations of ECB,
with six 8003 TeeJet hollow cone nozzles
(three per row). Two nozzles were directed
toward the ear zone with drops and one
nozzle directed over the row. A compressed-air
system was calibrated to deliver 15.2
gpa at 20 psi and a speed of 2.5.
Post-treatment Evaluations of
Injury
On September 21, five corn plants from
each of the middle two rows were split
with a corn knife for evaluation. Evaluations
of injury to the ear, ear shank, stalk
above the ear, and stalk below the ear
were recorded separately for each plant.
The mean percentages of plants with
cavities, mean numbers of cavities per
plants, the lengths of stalk tunneling
(cm) per plant, and the number of live
larva per plant were recorded.
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 Multiple Range Test (MRT) (P=0.05).
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Results and Discussion |
Results of all evaluations are presented
in tables 7.2 and 7.3. Percentage of
plants injured by corn borers and mean
numbers of larvae, numbers of cavities,
and cavity length per plant are shown
in Table 7.2. Mean numbers of larvae,
numbers of cavities, and cavity lengths
per plant below the ear are shown in
Table 7.3.
Survival of second-generation European
corn borer larvae survival was quite
high; at least 52% of the plants in
all plots had cavities (Table 7.2).
In addition, a natural infestation of
second-generation European corn borers
occurred several days after the insecticides
were applied. Nevertheless, the percentages
of injured plants in plots treated with
Warrior T 1SC and Tracer 2SC at 0.015
lb (AI)/acre and 0.031 lb (AI)/acre
were significantly lower than the percentage
of injured plants in the untreated control
plots.
In the untreated control plots, the
mean number of larvae per plant, mean
number of cavities, and mean cavity
length were 3.3, 4.3, and 16.6 cm, respectively.
The mean numbers of larvae per plant
were significantly lower in plots treated
with Mustang 1.5EC at 0.44 lb (AI)/acre,
Warrior T 1SC, Y-1, and Tracer 2SC at
0.015 and 0.031 lb (AI)/acre than in
the untreated control plots. The mean
numbers of cavities per plant were significantly
lower in plots treated with Warrior
T 1SC, Y-1, and Tracer 2SC at 0.015
and 0.031 lb (AI)/acre than in the untreated
control plots. The mean cavity lengths
per plant were significantly shorter
in plots treated with Warrior T 1SC
and Tracer at 0.015 and 0.031 lb (AI)/acre
than in the untreated control plots.
Measurements of numbers of corn borers
and injury below the ear (Table 7.3)
were similar to measurements for entire
plants, with some exceptions. In the
untreated control plots, the mean number
of larvae per plant, mean number of
cavities, and mean cavity length were
2.3, 2.3, and 8.3 cm, respectively.
The mean numbers of larvae per plant
were significantly lower in all insecticide-treated
plots than in the untreated control
plots. The mean numbers of cavities
per plant were significantly lower in
plots treated with Warrior T 1SC, Mustang
1.5EC at 0.03 lb (AI)/acre, and Tracer
2SC at 0.015 and 0.031 lb (AI)/acre
than in the untreated control plots.
The mean cavity lengths per plant were
significantly shorter in plots treated
with Warrior T 1SC and Tracer at 0.015
and 0.031 lb (AI)/acre than in the untreated
control plots.
Although the percentages of injured
plants were unacceptably high (from
a producer’s standpoint) in all
insecticide-treated plots, some significant
differences among treatments were apparent,
particularly with regard to the numbers
of European corn borer larvae per plant.
Warrior T 1SC and Tracer 2SC significantly
reduced the numbers larvae, numbers
of cavities, and cavity lengths.
References Cited
How a Corn Plant Develops,
Special Report No. 48, Iowa State University
of Science and Technology, Cooperative
Extension Service, Ames, Iowa. Ritche
et al. Reprinted June, 1993. |
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Table 7.1. |
Agronomic
factors and evaluation dates for insecticide
efficacy trials for control of second-generation
European corn borer Urbana, Illinois,
2000. |
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| Variables
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Urbana |
| Planting date
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June 7, 2000
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| Hybrid |
Pioneer 34G81
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| Plant population
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28,500 plants
per acre |
| Row spacing |
30 in |
| Soil condition
(top 2-3 inches) |
Moist |
| Previous crop
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Soybeans |
| Soil insecticide
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Force 3G applied
at planting |
| Infestation dates
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August 16 and
18 |
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5 egg
masses (black-head stage) per
plant per date |
| Treatment date
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August 21 |
| Air temperature
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75o
F |
| Wind |
0—5 mph
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| Evaluation date
(Stalk splitting) |
September 21
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Table 7.2. |
Mean
numbers of corn borer larvae, number
of cavities, and cavity length (cm),
per plant for the second-generation
European corn borer efficacy trial,
Urbana, Illinois, 2000 |
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Treatment |
Rate1
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% Damaged plants
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Mean no. of
larvae per plant2
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Mean no. of
cavities per plant2
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Mean Cavity
length (cm) per plant2
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| Mustang
1.5EW |
0.044 |
85.0
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a |
1.5
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b |
2.5
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a-e
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11.5
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ab
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| Warrior
T 1SC |
0.025 |
62.5
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bc
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0.9
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b |
1.2
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cde
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4.5
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bc
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| X-1
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0.025 |
90.0
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a |
1.5
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ab
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2.9
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abc
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12.7
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a |
| X-2
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0.030 |
87.5
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a |
2.0
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ab
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2.8
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a-d
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12.7
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a |
| X-3
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0.035 |
95.0
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a |
2.1
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ab
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3.5
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ab
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14.8
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a |
| Y-1
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0.030 |
82.5
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ab
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1.3
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b |
2.3
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b-e
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9.8
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abc
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| Mustang
1.5 EW |
0.030 |
92.5
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a |
1.7
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ab
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2.8
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a-d
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11.3
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ab
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| Tracer
2SC |
0.015 |
52.5
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c |
0.6
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b |
1.0
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e |
3.4
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c |
| Tracer
2SC |
0.031 |
55.0
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c |
0.5
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b |
1.1
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de
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4.7
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bc
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Control |
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92.0 |
a |
3.3 |
a |
4.3 |
a |
16.6 |
a |
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1All
rates are specified as lb (AI)/acre.
2Means in a column followed
by the same letter are not significantly
different (P=0.05; Duncan’s New
MRT). |
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Table 7.3. |
Mean
numbers of corn borer larvae, numbers
of cavities, and cavity length (cm)
per plant below the ear for second-generation
European corn borer insecticide efficacy
trial, Urbana, Illinois, 2000 |
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Treatment |
Rate1
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Injury below
the ear2 |
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Mean no. of
larvae per plant |
Mean no. of
cavities per plant |
Mean Cavity
length (cm) per plant |
| Mustang
1.5EW |
0.044
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0.8
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b |
1.2
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abc
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4.8 |
ab
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| Warrior
T 1SC |
0.025
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0.4
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b |
0.5
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c |
1.6 |
b |
| X-1
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0.025
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0.9
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b |
1.4
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abc
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5.7 |
ab
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| X-2
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0.030
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1.0
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b |
1.5
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abc
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5.5 |
ab
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| X-3
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0.035
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1.0
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b |
1.8
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ab
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7.1 |
a |
| Y-1
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0.030
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0.8
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b |
1.3
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abc
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5.4 |
ab
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| Mustang
1.5 EW |
0.030
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0.6
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b |
1.2
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bc
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4.9 |
ab
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| Tracer
2SC |
0.015
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0.4
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b |
0.6
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c |
1.6 |
b |
| Tracer
2SC |
0.031
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0.3
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b |
0.6
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c |
1.9 |
b |
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Control |
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2.3 |
a |
2.3 |
a |
8.3 |
a |
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1All
rates are specified as lb (AI)/acre.
2Means in a column followed
by the same letter are not significantly
different (P = 0.05; Duncan’s
New MRT) |
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Table 7.4. |
Mean
numbers of corn borer larvae, numbers
of cavities, and cavity length (cm)
per plant above the ear for second-generation
European corn borer insecticide efficacy
trial, Urbana, Illinois, 2000 |
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Treatment |
Rate1
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Injury above
the ear2 |
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Mean no. of
larvae per plant |
Mean no. of
cavities per plant |
Mean Cavity
length (cm) per plant |
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Mustang 1.5EW |
0.044 |
0.6 |
a |
1.3 |
a-d |
6.7 |
ab |
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Warrior T 1SC |
0.025 |
0.5 |
a |
0.7 |
cde |
2.9 |
cd |
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X-1 |
0.025 |
0.7 |
a |
1.5 |
abc |
7.0 |
ab |
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X-2 |
0.030 |
1.0 |
a |
1.3 |
a-d |
7.2 |
ab |
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X-3 |
0.035 |
1.1 |
a |
1.7 |
ab |
7.7 |
ab |
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Y-1 |
0.030 |
0.5 |
a |
0.9 |
b-e |
4.3 |
bcd |
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Mustang 1.5 EW |
0.030 |
1.1 |
a |
1.6 |
ab |
6.3 |
abc |
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Tracer 2SC |
0.015 |
0.2 |
a |
0.4 |
e |
1.8 |
d |
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Tracer 2SC |
0.031 |
0.2 |
a |
0.6 |
de |
2.8 |
cd |
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Control |
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1.0 |
a |
1.9 |
a |
8.3 |
a |
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1All rates are specified
as lb (AI)/acre.
2Means in a column
followed by the same letter are not
significantly different (P = 0.05; Duncan’s
New MRT) |
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Table 7.5 |
Mean
numbers of corn borer larvae and cavities
in the shank, and percentage ear damage
and larvae in the ear for second-generation
European corn borer insecticide efficacy
trial, Urbana, Illinois, 2000 |
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Shank damage2
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Ear damage2
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Treatment |
Rate1
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Mean no. of
larvae per plant |
Mean no. of
cavities per plant |
Mean no. of
larvae per ear |
% Damage |
| Mustang
1.5EW |
0.044
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0.3
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ab
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0.5
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a-d
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0.3
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bcd
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65.0
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ab
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| Warrior
1SC |
0.025
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0.0
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b
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0.2
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de
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0.4
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a-d
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70.0
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ab
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| X-1
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0.025
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0.3
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ab
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0.6
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abc
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0.6
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ab
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85.0
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a
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| X-2
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0.030
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0.2
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ab
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0.4
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a-e
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0.4
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a-d
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80.0
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a
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| X-3
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0.035
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0.3
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ab
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0.4
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a-e
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0.6
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abc
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80.0
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a
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| Y-1
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0.030
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0.1
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ab
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0.3
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b-e
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0.3
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d
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77.5
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a
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| Mustang
1.5 EW |
0.030
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0.3
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ab
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0.6
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ab
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0.4
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bcd
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75.0
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a
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| Tracer
2SC |
0.015
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0.1
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b
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0.1
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e
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0.2
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d
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35.0
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c
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| Tracer
2SC |
0.031
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0.1
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ab
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0.3
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cde
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0.3
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cd
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42.5
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bc
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Control |
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0.4 |
a |
0.7 |
a |
0.7 |
a |
90.0 |
a |
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1All
rates are specified as lb (AI)/acre.
2Means in a column followed
by the same letter are not significantly
different (P = 0.05; Duncan’s
New MRT). |
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