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Group Title: Research Report - University of Florida Central Florida Research and Education Center ; 89-10
Title: Control of insecticide resistant Diamondback moth, Plutella Xylostella (Linnaeus), on cabbage, spring 1988
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Title: Control of insecticide resistant Diamondback moth, Plutella Xylostella (Linnaeus), on cabbage, spring 1988
Series Title: Research Report - University of Florida Central Florida Research and Education Center ; 89-10
Physical Description: Book
Language: English
Creator: Leibee, Gary L.
Savage, Kenneth E.
Publisher: University of Florida, Central Florida Research and Education Center
Publication Date: 1988
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Bibliographic ID: UF00075875
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 122378354

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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










University of Florida
CENTRAL FLORIDA RESEARCH AND EDUCATION CENTER
Sanford, Florida

Research Report SAN 89-10 December 1988

CONTROL OF INSECTICIDE RESISTANT DIAMONDBACK MOTH,
PLUTELLA XYLOSTELLA (LINNAEUS), ON CABBAGE, SPRING 1988


Gary L. Leibee and Kenneth E. Savage


'Little Rock' cabbage was transplanted March 31, 1988, in Myakka
fine sand on the University of Florida's Central Florida Research and
Education Center in Sanford, FL. A plot consisted of four 50' rows with
12" plant spacing. Each plot was separated by four unplanted rows; row
spacing was 30". Nemacur 15G 2.0 Ib ai/acre was applied pretransplant
in 15" band for nematode control. Randox 4EC and Vegedex 4EC both at
2.0 lb ai/acre were applied for weed control two days after transplant.
Treatments were replicated in four randomized complete blocks separated
by 20' weed-free alleys. Sprays were applied with a tractor-mounted,
compressed-air sprayer. Three nozzles (D2-25) were used per row, one
overhead and one drop on each side. The delivery rate was 50 gpa with a
* boom pressure of 45 psi and a speed of 2 mph. Application dates were
April 20, 27, May 4, 11, 18, 26, and June 1, 1988. Insecticides and
rates per acre tested were Dipel 4F (Abbot) at 8 and 16 BIU, Dipel 2X
(Abbot) at 7.3 BIU, Lannate 1.8L (E. I. duPont de Nemours & Co., Inc.)
at 0.9 Ib ai, Lorsban 50W (The Dow Chemical Co.) at 1.0 lb ai, Pounce
3.2EC (FMC Corp.) at 0.15 Ib ai, Cymbush 3EC (ICI Americas, Inc.) at
0.06 Ib ai, Pydrin 2.4EC (E. I. duPont deNemours & Co., Inc.) at 0.2 Ib
ai, and Karate (ICI Americas, Inc.) 12WG at 0.020 and 0.025 lb ai and
1EC at 0.025 Ib ai. Several adjuvants were used in this experiment due
to the preferences of the companies involved. Dipel 4F, and Pounce were
used with Plyac (Hopkins Agricultural Chemical Co.) spreader-sticker at
the rate of 1.2 ml/gallon. Dipel 2X and Lannate were used with Bond
(Loveland Industries, Inc.) spreader-sticker at the rate of 10
ml/gallon. Lorsban, Cymbush, Pydrin, and Karate were used with X-77
(Chevron Chemical Co.) at the rate 2.4 ml/gallon. Samples were taken on
May 31, 1988, to determine the number of larvae per 4 plants. Four
plants were randomly chosen per plot, 2 from the middle of each center
row. The plants were cut off at ground level and sloshed up and down
ten times in an inverted position in 3 gal of water in a 6-gal bucket.
All 4 plants were washed in the same water and then the water was sieved
through a fine-mesh cloth to collect the larvae. The larvae were stored
in 70% ethyl alcohol and categorized according to species and size
(small, medium, or large). Damage ratings were taken on June 9 when
heads were mature. The damage rating for each plot was determined by
averaging the damage rating for 10 mature heads (five consecutive heads
9 in each of the middle rows). The damage rating scale was 1-6, similar
to Greene et al., Jour. of Econ. Entomol. 62(4):798-800. Percent
marketability was based on proportion of heads with a damage rating of
3.00 or less. Yield (average head weight) was determined from the
weights of 6 randomly selected (3 from the middle of each center row)
heads (including 3-4 wrapper leaves) per plot.












The infestation was very heavy and consisted of essentially all
diamondback moth (DBM), Plutella xvlostella (Linnaeus). DBM populations
have become very difficult to control with pyrethroids, organo-
phosphates, and carbamates in the last two years in central Florida
(personal observation). Laboratory studies have indicated a high level
of resistance to fenvalerate and methomyl, and a lower level of
resistance to methamidophos (Leibee, unpublished data). The lack of
control of DBM in this experiment by pyrethroids, methomyl, and
chlopyrifos indicated that a highly resistant population was present
(Table 1). Chlorpyrifos was more effective at reducing larval numbers
and damage than the pyrethroids and methomyl, but insect control was
still unacceptable. Dipel 4F and 2X at 8 BIU were not effective and
there was no apparent difference due to formulation. They reduced the
number of medium-large larvae to a level where control might be
expected, but the amount of damage was unacceptable. Dipel 4F at 16 BIU
was much more effective at reducing damage (85% marketability) than at 8
BIU (25% marketability). This might be explained by the fact that Dipel
4F at 8 BIU allowed approx. three times as many medium-large larvae to
develop than at 16 BIU. This tripling of the number of medium-large
larvae may have exceeded a critical level where the resulting increase
in damage would put more plants into the unmarketable category. Yield
data was not significant (P>0.05), apparently due to large variations in
plant size caused by variable moisture conditions that could not be
accounted for in the experimental design. No problems with formulations
were encountered and no phytotoxicity was observed.











Table 1. Effects of various insecticide treatments on the number of
larvae, damage levels, and marketability of cabbage infested with a
highly insecticide resistant population of diamondback moth, Plutella
xylostella (Linnaeus).


No. ofl
Insecticide medium-large Total no.1
ai/acre larvae/plant larvae/plant DR2 %M2


Untreated check 26.38 b-e 56.69 d-h 6.00 0.0

Dipel 2X 7.3 BIU 6.19 f-i 35.31 f-j 3.80 22.5

Dipel 4F 8 BIU 11.50 e-h 48.63 e-i 3.63 25.0

Dipel 4F 16 BIU 3.44 f-i 25.81 g-j 2.48 85.0

Lannate 1.8L .9 lb. 33.69 a-d 124.31 ab 4.48 0.0

Lorsban 50W 1.0 lb. 17.19 c-f 75.69 b-f 4.35 7.5

Pounce 3.2EC 0.15 lb. 29.31 b-e 111.94 abc 5.20 0.0

Cymbush 3EC .06 lb. 65.25 a 136.81 ab 6.00 0.0

Pydrin 2.4EC 0.2 lb. 46.88 ab 142.94 a 6.00 0.0

Karate 12WG .020 lb. 48.50 ab 107.50 a-d 6.00 0.0

Karate 12WG .025 lb. 39.44 abc 103.31 a-d 6.00 0.0

Karate 1EC .025 lb. 39.19 abc 99.56 a-e 6.00 0.0


1Sample date was May 31, 1988. Means within each column followed by the
same letter are not significantly different at the 0.05 level by DMRT.
Analyses of variance were performed on transformed data (sqrt(X + .5)).


2DR damage rating and %M percent marketability.




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