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of Florida

S/00 AGRICULTURAL RESEARCH & EDUCATION CENTER
676 IFAS, University of Florida
l(C Bradenton, Florida

7~AREC Bradenton Research Report CC1979-8 April 1979

A RESEARCH UPDATE ON THE CONTROL OF V LIBI
VEGETABLE LEAFMINER WITH CHEMICAL 91979
OCT 9 1979
D. J. Schuster and P. H. Everett
.F.A.S.- Univ. of Fiorida
The vegetable leafminer, Liriomyza sativae Blanchard, is an insect
pest of major concern to tomato producers in Florida. Leafminers develop
in the mesophyll leaf tissue producing characteristic serpentine mines.
Eggs are oviposited directly into the leaves, thus protecting hatching
larvae from the action of contact insecticides. After tunneling the leaves,
the mature, yellow larvae emerge from the leaves and form orange puparia
on leaves, mulch or soil. Adults emerge to renew the life cycle, completing
development in about 7 to 14 days, depending upon temperature.
Numerous experiments have been conducted in the field to investigate
the relative efficacy of various insecticides to control L. sativae. During
2 Spring 1976 field experiments, insecticides were applied weekly to
'Walter' tomato plants starting about 2 weeks following transplanting and
continuing to harvest. In the first experiment, Ambush, PP383 and Pounce
(0.10 Ib ai rate) gave better control than Azodrin (Table 1). In Experiment
2, Monitor, Azodrin and Cygon were superior to Diazinon in reducing
leafminer damage. All insecticides reduced the number of leafmines relative
to the unsprayed check in both experiments.
In the Spring of 1977, insecticides were applied weekly in a grower's
field to 'tWalter' plants beginning about 10 days before the first harvest
(Table 2). Leafminer damage was severe at that time averaging about 25%
defoliation. Nevertheless, a significant reduction in the number of
leafmines and percent defoliation was observed on plants sprayed with Ambush
and Bolstar. Although Vydate and Pydrin reduced the number of leafmines
2 weeks after spraying was initiated, control, as measured by defoliation,
was not good after 6 weeks.
In another grower field test in the Fall 1977, fruiting 'Walter' tomato
plants were sprayed 4 times with insecticides at weekly intervals (Table 3).
Significant reductions in the number of total and active leafmines were
observed for Pydrin, Ambush, Vydate, Monitor, Pounce and Bolstar. Cygon
did not reduce leafminer damage.
In a final experiment in a commercial field in Spring 1978, 'Walter'
tomato plants were sprayed weekly beginning about 6 weeks before harvesting
began. Some insecticides were not applied every week due to label restrictions
in the spray interval before harvest. Only Ambush and Pounce significantly
reduced the total number of leafmines after 6 applications (Table 4).
However, Monitor had not been applied within 2 weeks of the evaluation due
to a 14 day harvest interval restriction. Azodrin had only been applied once
because of its 21 day harvest interval. Both of these insecticides had
demonstrated efficacy in previous experiments but would require supplemental
insecticides to maintain control through harvest.

The synthetic pyrethroids Ambush and Pounce appeared to have the
greatest control potential relative to other chemicals in several experiments.
This was true whether relatively small (Fall 1977, Spring 1978) or high
(Spring 1976 and 1977) populations of the leafminer were present. Monitor
gave significant control relative to unsprayed plants whenever the chemical
was applied weekly. Other insecticides will be necessary when control is
needed within 14 days of harvest. Vydate significantly reduced leafminer
damage when populations were light (Fall 1977) but not when they were
heavy (Spring 1977).

The use of trade names is with the understanding that no discrimination is
intended and no endorsement by the University of Florida or the authors is
implied, to the exclusion of other, equally effective materials.

Table 1. Control of the vegetable leafminer on tomato plants sprayed
weekly with insecticides (ARC-Immokalee). Spring 1976.

Treatment Lb ai/100 gal No. leafmines/10 trifoliates1

Expt. 1 Expt. 2

Ambush 2EC 0.20 137.0 a2
PP 383 2EC 0.05 151.8 ab
Pounce 3.2EC 0.10 158.6 abc
Pounce 3.2EC 0.05 193.5 cd -
Bolstar 6EC 1.00 185.9 bcd -
Azodrin 5EC 1.00 213.4 de 164.1 a
Monitor 4EC 0.50 149.7 a
Cygon 2.67EC 0.50 -169.7 a
Diazinon 4EC 0.50 198.2 b
Check 317.1 f 232.4 c

1Averaged over 4 counts made every 2 weeks. A trifoliate is 3 terminal
leaflets.
Means within columns followed by the same letter are not significantly
different at the P=0.05 level, Duncan's multiple range test.

Table 2. Control of the vegetable leafminer on tomato plants sprayed
weekly with insecticides (Manatee Co.). Spring 1977.

No. leafmines/1 %
Treatment Lb ai/100 gal 10 trifoliates defoliation

Ambush 2EC 0.1 28.1 a3 43.8 a
Bolstar 6EC 1.0 31.0 a 52.6 b
Vydate 2L 1.0 36.8 ab 89.0 d
Pydrin 2.4EC 0.1 69.0 b 66.1 c
Check 106.8 c 90.2 d

Counts were made 2 weeks after the initial spray. A trifoliate is 3
terminal leaflets.
3Defoliation was estimated 6 weeks after the initial spray.
Means within columns followed by the same letter are not significantly
different at the P=0.05 level, Duncan's multiple range test.

Table 3. Control of the vegetable leafminer on tomato plants after 4
weekly insecticidal sprays (Hillsborough, County). Fall 1977.
No. leafmines/10 trifoliatesi
Treatment Lb ai/100 gal Total Active

Pydrin 2.4EC 0.1 5.5 a2 0.5 ab
Ambush 2EC 0.1 6.5 a 0.0 a
Vydate 2L 1.0 8.0 a 1.2 ab
Monitor 4EC 1.0 8.5 a 0.0 a
Pounce 3.2EC 0.1 10.2 a 2.0 ab
Bolstar 6EC 1.0 11.0 a 0.2 a
Cygon 4EC 0.5 28.2 b 8.5 c
Check 26.5 b 6.5 c

1A trifoliate is 3 terminal leaflets.
2Means followed by the same letter are
P=0.05 level by the Duncan's multiple

not significantly different at the
range test.

Table 4. Control
weekly

of the vegetable leafminer on tomato plants sprayed
with insecticides (Manatee County). Spring 1978.

No. leafmines/5 trifoliates1
Treatment Lb ai/100 gal Total Active

Ambush 2EC 0.10 29.5 a2 5.5 a
Pounce 3.2EC 0.10 32.5 a 10.0 ab
Pydrin 2.4EC 0.10 45.2 ab 7.5 ab
Monitor 4EC 1.00 51.2 abc 11.5 abcd
Diazinon 50WP 0.25 60.2 bcd 14.5 abcd
Orthene 75SP 1.00 61.5 bcd 11.7 abcd
Bolstar 6EC 1.00 63.0 bcd 14.2 abcd
Dibrom 8EC 1.00 63.2 bcd 14.2 abcd
Azodrin 5EC 1.00 63.5 bcd 15.0 abcd
Parathion 8EC 1.00 64.2 bcd 18.2 abcd
Toxaphene 8EC 1.00 65.0 bcd 11.2 abc
Lannate 90SP 0.45 66.2 bcd 16.2 abcd
Guthion 50WP 0.50 67.0 bcd 16.5 abcd
Thiodan 2EC 1.00 76.7 cd 25.7 d
Trithion 8EC 1.00 78.2 cd 24.5 cd
Cygon 4EC 0.50 78.7 cd 16.5 abcd
Ethion 4EC 0.50 82.7 d 25.7 d
Phosphamidon 8EC 0.50 82.7 d 20.7 bcd
Dylox 80SP 1.00 84.0 d 21.2 bcd
Dipel WP 1.00 85.2 d 22.5 cd
Check (Water) 71.2 bcd 14.0 abcd

1Counts were made after 6 applications except for Azodrin and Dylox which
were sprayed once and Monitor, Parathion, Toxaphene, and Phosphamidon
which were sprayed 3 times because of harvest intervals. A trifoliate is
3 terminal leaflets.
Means followed by the same letter are not significantly different at the
P=0.05 level by the Duncan's multiple range test.