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Group Title: Research report - UF Agricultural Research and Education Center ; CF-76-5
Title: Efficacy of certain insecticides against lepidopterous pests of cabbage
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Permanent Link: http://ufdc.ufl.edu/UF00075828/00001
 Material Information
Title: Efficacy of certain insecticides against lepidopterous pests of cabbage
Series Title: Research report - UF Agricultural Research and Education Center ; CF-76-5
Physical Description: Book
Language: English
Creator: Denton, William H.
Publisher: Agricultural Research and Education Center, University of Florida
Publication Date: 1976
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Bibliographic ID: UF00075828
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 123071294

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






S-AGRICULTURAL RESEARCH AND EDUCATION CENTER
Sanford, Florida

Research Report CF76-5 December 1, 1975

Efficacy of Certain Insecticides Against
Lepidopterous Pests of Cabbage ..

William H. Denton L..
Assistant Entomologist /

INTRODUCTION tp 2 1977

The cabbage looper, Trichoplusia ni (Hubner), co ,ito :the most
serious pest of cabbage in central Florida. On occasion, eahRfle- rid
diamondback moth, Plutella xylostella (L.), and the imported cabbage'Wrm,
Pieris rapae (L.), cause significant damage.

Frequently, repeated applications of currently available insecticides are
necessary throughout the season to produce marketable cabbage. Certain of
these materials have been reported by growers to be inadequate during heavy
infestations.

The results shown in this report are not intended as insect control
recommendations. The primary concern of this trial is to evaluate chemicals
for possible inclusion in an experimental overall pest management approach
for cabbage production in Florida.

METHODS AND MATERIALS

These tests were conducted at the Center's farm near Sanford, Florida.
The soil type is Leon fine sand. The field was fumigated with 20 gallons per
acre of a dichloropropane-dichloropropene mixture for control of nematodes
prior to planting.

A standard commercial variety, Rio Verde cabbage, was propagated in
seedbeds at the Sanford farm and maintained with mancozeb and chlordimefowm.
The seedlings were transplanted on January 28, 1975, into four blocks of 16
plots each. Each plot consisted of three 50-ft. rows with 30-in. row spacing,
and 10-in. plant spacing within the row. The plots were separated by a guard
row.

For weed control, CDEC and alachlor, in combination, were applied on
January 29 at the rate of 3.0 lb. and 1.5 lb. active ingredient, respectively.

Insecticides (Table 1) were applied at a.rate of 100 gallons per acre at
100 psi with tractor-mounted spray equipment using a three-row boom. Twe
over-the-row nozzles with one dropped nozzle directed at either side of the
row were used. This equipment is comparable to ground application equip-
ment used by commercial growers.





Table 1. Insecticide treatments applied to cabbage from March 27 through
April 29, 1975.


Treatment
number Trade name Common name Rate


Monitor 4E
Lannate S (90%)
Lannate L (1.9E)
Orthene 75S
Orthene 2.67 EC
Fundal 4E
Dipel
Biotrol XK
Bay NTN 9306 6 EC
RH 40967
it
FMC 33297 0.8 EC
it
SD 43775 2. 4 EC
Untreated
Untreated


methamidophos
methomyl

acephate
ti
chlordimeform
Bacillus thuringiensis
I1 I1

Bacillus thuringiensis

pyrethrold
Ii
it


0. 5 lb. ai/acre
0.45
0.45
0.5 "
0.5
0.5 "
0.5 lb. formulation
1.0 "
1.0 lb. ai/acre
0. 25 lb. formulation
0.5 "
0.05 lb. ailacre
0.1 "
0.05 "


Applications of insecticide were made, weather permitting, at weekly
intervals. The first applications, with the exception of SD 43775, were made
on March 27 after sufficient numbers of lepidopterous pests were observed.
Subsequent applications included SD 43775, and were applied on April 4, 16,
24, and 29. Thus, the compound SD 43775 was applied four times, all the
other compounds were applied five times prior to harvest.

One week after the final application, insect damage on 10 plants per plot
(40 plants per treatment) was rated according to a method based on the
intensity of insect feeding as reported by Greene, et al. (1969). Plants
with damage ratings of 3 or below were marketable: The rating system is
as follows:

1 = No apparent insect feeding
2 = minor feeding on outer leaves, 1% or less leaf area eaten
3 = moderate feeding on wrapper or outer leaves with no head damage,
2-5% leaf area eaten
4 = moderate feeding on wrapper or outer leaves with minor feeding on
head, 6-10% leaf area eaten. Head unmarketable during normal
market conditions.
5 = moderate to heavy feeding on wrapper and head leaves and a moderate
number of feeding scars on head, 11-30% of leaf area eaten.
6 = considerable feeding on wrapper and head leaves with numerous feeding
scars on head, over 30% of leaf area eaten.








RESULTS AND DISCUSSION


Based on the data collected prior to the first application of insecticides,
the pest population (Table 2) could be classed as moderate.

Only the untreated plots and Bay NTN 9306 at 1. 0 lb. ai/acre had excessive
damage at harvest on May 6, 1975. The statistical comparisons are shown in
Table 3. With the untreated included in the analysis, Bay NTN 9306 was not
significantly different from the untreated.

A more realistic comparison can be made, however, if the untreated plots
are omitted from the analysis and comparisons made between the treated plots
alone. These comparisons indicate that FMC 33297 at 0.1 lb. ai/acre provided
superior control while Bay NTN 9306 gave the least protection. All other
compounds provided intermediate levels of protection.

The percentage of unmarketable heads (rating of 4 or higher) in the 40
plant sample for FMC 33297 at 0. 1 lb. ai/acre was 2. 5. The sample from
Bay NTN 9306 had 62.5% unmarketable heads compared to 70% of the 80 plants
from the two untreated plots.

The efficacy of SD 43775 may be greater than indicated by these comparisons.
Due to a delayed shipment and the late inclusion of this compound in the trial,
only an indication of good performance may be inferred.

Based on efficacy data alone, the new synthetic pyrethroids, represented
in this test by FMC 33297 and SD 43775, may provide a valuable alternative in
an overall pest management system for cabbage production. However, no data
was collected on the effects of these chemicals on nontarget organisms.





Table 2. Mean numbers of various stages of three lepidopterous pests per
10 plants (n=4) on March 24, 1975.


Treatment Cabbage Looper Imported Cabbage worm Diamondback Moth
number Eggs Larvae Pupae Eggs Larvae Pupae Larvae Pupae

1 5.75 1.75 0.75 2.00 0.00 0.50 0.00 0.25
2 7.25 2.00 0.75 2.25 0.00 0.25 0.00 0.50
3 4.00 4.50 0.25 2.00 0.00 0.25 0.25 0.50
4 6.50 1.75 1.00, 2.75 0.00 0.50 0.25 0.50
5 3.25 0.75 0.50 4.25 0.00 0.00 0.00 0.00
6 5.25 2.25 0.50 3.25 0.00 0.25 0.25 0.25
7 3.50 4.50 0.00 3.25 0.00 0.00 1.00 0.50
8 9.00 6.00 0.50 1.50 0.00 0.00 1.50 0.00
9 6.25 5.50 0.25 2.75 0.00 0.00 0.25 0.25
10 3.75 7.75 0. 50 4.25 0.00 0.00 0.25 0.75
11 8.25 2.25 0.25 1.00 0.00 0.25 0.50 0.751
12 6.25 1.50 .1.00 0.75 0.00 0.25 0.00 0.50
13 6.75 0.75 0.00 1.75 0.00 0.25 0.00 0.75
14 8.50 10.00 1.00 2.50 1.25 0.25 0.25 0.50
15 3.00 7.00 0.00 4.00 0.75 0.25 0.50 1.50
16 6.00 6.75 0.25 2.25 1.50 0.50 2.00 1.00



1/
Table 3. Ratings of insect damage to cabbage at harvest. Ranked by average
damage.


2/
Treatment Replication Mean Comparisons-
number A B C D (40 plants) (1) (2)

13 .1.0 1.0 1.4 1.0 1.10 a a
1 1.0 1.4 1.0 1.2 1.15 a b
5 1.0 1.4 1.0 1.2 1.15 a b
4 1.0 1.3 1.0 1.4 1.18 a b
12 1.0 1.0 1.3 1.6 1.23 a bc
6 1.0 1.4 1.8 1.8 1.50 ab bcd
2 1.4 1.6 1.9 2.2 1.78 ab bcde
7 1.6 1.7 2.6 1.9 1.95 ab bcde
3 1.3 1.5 2.1 3.2 2.03 ab bcde
10 1.0 2.4 1.9 2.8 2.03 ab bcde
14 1.2 3.0 2.4 2.0 2.15 ab cde
11 3.2 2.1 1.0 2.7 2.25 ab de
8 3.0 2.1 2.6 2.6 2.58 b e
9 3.4 4.6 2.9 4.1 3.75 c f
15 3.3 3.3 3.3 5.4 3.83 c
16 3.8 3.7 4.8 4.5 4.20 c


G. L. et al.


1969. Cabbage looper control in Florida A cooperative


program. J. Econ. Entomol. 62:798-800.
I2uncan's new multiple range test: (1) with untreated included, (2) with untreated
excluded, Means followed by the same letter are not significantly different (P=. 01).


1Green,




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