LEAFLET 74
MAY 1967
il
Agricultural Experiment Station
A U BURN U NIVE RS ITY
E. V. Smith, Director Auburn, Alabama
TOMATO
FRUIT WORM
CONTROL
TOMATO FRUITWORM
CONTROL
T. DON CANERDAY-
Department of Zoology-Entomology
TOMATOES ARE GROWN by most home
gardeners and approximately 4600 acres
of field tomatoes were grown commer-
cially in Alabama in 1966 for fresh mar-
ket. There are several important insect
pests of field tomatoes including tomato
fruitworm, aphids, leafminers, horn-
worms, and loopers. The tomato fruit-
worm Heliothis zea (Boddie), is usually
the most economically important insect
attacking tomatoes, and control programs
are generally directed specifically at this
pest.
THREE-YEAR
EXPERIMENTS
Some states have reported that 
H. zea
attacking cotton had become resistant 
to
certain insecticides. Hence, it was 
im-
portant to determine the effectiveness 
of
currently recommended as well as some
new materials against the fruitworm on
tomatoes. At the same time, plant 
re-
sponse to repeated insecticidal applica-
tions was measured in some experiments.
Experiments were conducted at the
North Alabama Horticulture 
Substation,
Cullman, and the Chilton Area Horticul-
ture Substation, Clanton, Alabama, 
from
1964 through 1966. Recommended and
1 The author gratefully acknowledges 
the
cooperation and assistance of M. H. Hol-
lingsworth, superintendent, North Alabama
Horticulture Substation; and C. C. Carlton
and Kenneth Short, superintendent and as-
sistant superintendent, respectively, Chilton
Area Horticulture Substation.
experimental insecticides were evaluated
for effectiveness against the fruitworm
on ground and trellis tomatoes. Insecti-
cides were applied with a fungicide,
maneb, and compared with maneb used
alone and an untreated check. In 1964,
plant response to sprayable and 
dust
formulations of carbaryl and TDE was
measured.
1964 Experiments. Three small-plot
field experiments were conducted in
1964, two at Cullman and one 
at Clan-
ton. One experiment at each location
was designed primarily to evaluate plant
response to repeated applications of in-
secticides. Plots were 3 rows wide and
25 feet long and treatments were re-
plicated 4 times in a randomized com-
plete block design (repeated 4 times in
plots to obtain averages for more reliable
comparisons). Homestead 24 tomato
variety was transplanted May 22 at 
Cull-
man and Marion variety was field seeded
approximately the same date at Clanton.
Prior to bloom three to eight plants per
plot were selected for size uniformity
and tagged for subsequent study.
Carbaryl at recommended and in-
creased rates was compared with TDE,
a fungicide alone, and untreated check.
Materials were applied as sprays at Cull-
man and dust formulations were used 
in
the Clanton test. Treatments were be-
gun at early bloom and applied five
times at weekly intervals. Sprays were
applied with a knapsack sprayer at the
[2 ]
rate of 80 gallons of spray material per
acre and dusts were applied with a
rotary-type hand duster.
Bloom counts were made weekly at
Cullman. When tomatoes began to ripen,
entire sacrificed plants were removed
from the field. All tomatoes on each
plant were counted, examined for insect
damage, and weighed. Also, the wet
weight of each vine was recorded.
In a second experiment at Cullman,
nine insecticidal treatments were com-
pared with an untreated check for fruit-
worm control. Seven applications were
made at weekly intervals from early
bloom until production terminated. All
materials were applied as sprays follow-
ing the procedure previously described.
Tomatoes were harvested periodically as
they ripened and examined for fruit-
worm damage. When final harvest was
made, all tomatoes half-grown and larger
were included in the sample. Unless
otherwise indicated, these same proce-
dures were followed in subsequent ex-
periments.
1965 Experiments. Certain insecticides
were evaluated for fruitworm 
control on
trellis-grown Marion variety tomatoes at
Cullman and Homestead 24 variety pro-
duced as ground tomatoes at Clanton.
Basic experimental design, treatment,
and harvest procedures were essentially
the same as previously described. Treat-
ments were begun at early fruit set in
the Clanton experiment. At Cullman, a
fruitworm infestation was allowed to de-
velop before treatment was begun. Plots
were sprayed nine times at Cullman and
five times at Clanton. The Cullman
planting was irrigated periodically to
maintain optimum soil moisture. Toma-
toes were harvested nine times at Cull-
man and four times at Clanton for yield
data.
1966 Experiments. Two experiments
were conducted on the Cullman station
and one at Clanton in 1966. Several
insecticides were evaluated for fruitworm
control. Roma 884, a mechanical harvest
variety, was planted in May at Cullman
and a fall planting of Homestead 24
variety was made at Clanton. Plot size
and design at Cullman were similar to
those used in earlier tests. At Clanton,
each treatment area was approximately
one-fourth acre and materials were ap-
plied with a tractor-mounted sprayer
calibrated to deliver 60 gallons of spray
material per acre. Treatments were be-
gun at early fruit set and applied at
weekly intervals. Yield data were ob-
tained by harvesting tomatoes at fre-
quent intervals.
Evaluation of insecticidal effectiveness
was based on percentage of damage to-
matoes or yield of marketable tomatoes
or both in all experiments.
RESULTS AND
DISCUSSION
1964 Experiments. Results of experi-
ments conducted at Cullman and Clan-
ton are summarized in Tables 1, 2, and
3. Carbaryl and TDE applied as sprays
gave excellent fruitworm control at Cull-
man based on percentage of damaged
fruit. All insecticidal treatments were
about equal in effectiveness and signifi-
cantly superior to maneb and the un-
treated check (Table 1). However, total
tomato yields from plots receiving ef-
fective fruitworm protection were not
superior to those of the maneb treatment.
There were no significant differences in
number of blooms per plant among the
treatments, but vine weights tended to
be greater in all treated plots as com-
pared with the untreated check. The
latter was primarily because of effective
disease control in all treated plots.
As given in Table 2, results at Clanton
were quite similar to those from the
Cullman experiment when the same in-
secticides were applied in dust formula-
tions. The percentage of tomatoes dam-
aged by the fruitworm was reduced by
all insecticidal treatments. Tomato yield
tended to be lower from the plots re-
ceiving no, insecticides; however, the
yield, total and undamaged, from plants
[3]
TABLE 1. RESPONSE OF TOMATO PLANTS TO INSECTICIDAL-FUNGICIDAL TREATMENTS
APPLIED AS SPRAYS FOR FRUITWORM CONTROL, NORTH ALABAMA HORTICULTURE
SUBSTATION, CULLMAN, ALABAMA, 1964
Mean
Active Fruit- Mno.
2  
Av. no. fruit and wt./plant
3  
Av.
Treatmentl per worm blooms plant
acre damage per 
Total Undamaged 
(wet)
plant
Lb. Pct. No. Lb. No. Lb. Lb.
Carbaryl+ Maneb__ 1+2 1.7a 15 23b 3.8b 22ab 3.7 1.92ab
Carbaryl+Maneb__ 2+2 2.0a 14 23b 4.3b 22ab 4.2 2.05ab
Carbaryl+Maneb__ 4+2 1.5a 15 29ab 5.2ab 28a 5.1 2.64a
TDE+Maneb -------- 1+2 2.4a 14 28b 4.8ab 27a 4.7 2.58a
Maneb 2 15.0b 15 35a 6.6a 30a 5.6 2.33ab
Untreated 0 17.0b 12 24b 4.5b 19b 3.6 1.69b
1 Materials applied July 8, 14, 21, 28, and Aug. 3.
2 Bloom counts made 
on treatment dates.
8 Whole plants sacrificed Aug. 10 for yield data. Means followed by the same letter
do not differ at the 0.05 level of protection (95 times out 
of 100).
TABLE 2. RESPONSE OF TOMATO PLANTS TO INSECTICIDAL-FUNGICIDAL TREATMENTS
APPLIED AS DUSTS FOR FRUITWORM CONTROL, CHILTON AREA
HORTICULTURE SUBSTATION, CLANTON, ALABAMA, 1964
Active Fruit- Av. no. fruit and wt./plant
2  
Av.
Treatment
1  
per worm plant
acre damage Total Undamaged wt. (wet)
Lb. Pct. No. Lb. No. Lb. Lb.
Carbaryl 5%+Zineb 6% 1+2 8.4ab 12.0 1.38 11.0ab 1.26 1.73
Carbaryl 5%+Zineb 6% 2+2 7.6ab 14.0 1.58 13.1a 1.46 2.03
Carbaryl 10%+Zineb 6% 4+2 2.6a 13.3 1.62 13.0a 1.58 1.92
TDE 5%+Zineb 6%..... 1+2 4.8a 11.5 1.36 11.0ab 1.30 1.76
Zineb 6% 2 16.2bc 13.8 1.60 11.5ab 1.34 1.85
Untreated 0 27.4c 10.9 1.55 7.9b 1.13 1.41
1 Materials applied Aug. 14, 20, 27, Sept. 9 and 16.
2 Whole plants sacrificed Sept. 14 and 21 for yield data. Percentage of fruitworm
damage tested at 0.01 level for significance (99 times out of 100) and undamaged at 0.05
level (95 times out of 100); means followed by same letter are not significant statistically.
receiving insecticides was not signifi-
cantly superior to the zineb-treated
plants.
Carbaryl and TDE applied as sprays
or dusts effectively controlled the tomato
fruitworm in these experiments. How-
ever, at the fruitworm population density
encountered, these materials applied in
combination with a fungicide did not
significantly increase fruit set when com-
pared with that from a fungicide treat-
ment alone.
Results from a second experiment con-
ducted at Cullman where nine insecti-
cidal treatments were evaluated for to-
mato fruitworm control are given in
Table 3. Fruitworm damage was not
heavy in this experiment as shown by
the low level of injury to untreated
plants. However, plots treated weekly
with the following materials at indicated
per acre rates yielded significantly fewer
damaged tomatoes than plots receiving
no treatment: Toxaphene+DDT, 2+1;
carbaryl, 2; Naled, 2; toxaphene, 3;
Thuricide, 90T; or endosulfan, 0.5. All
of these materials were found to be equal
in effectiveness when tested at the 0.05
level of protection. Weekly applications
of toxaphene+DDT or TDE were more
effective than carbaryl or Naled at 1
pound per acre applied every 2 weeks.
[41
TABLE 3. EFFECTIVENESS OF VARIOUS IN-
SECTICIDES FOR FRUITWORM CONTROL ON
GROUND TOMATOES, NORTH ALABAMA HOR-
TICULTURE SUBSTATION, CULLMAN,
ALABAMA, 1964
Active
Treatment per
acre
Lb.
2+1
1
2
2
3
1 qt.
0.5
2
1
0
Toxaphene+
DDT
TDE
Carbaryl -----------
N aled ---------------
Toxaphene ...
Thuricide 90T
Endosulfan ...
Carbaryl
3 
..........
Naled
Untreated ---------
Tomatoes Fruit-
ex-
aminedl
No.
866
946
957
1120
955
917
1251
624
723
870
worm
damage
2
Pct.
3.2a
3.9a
4.0ab
4.4ab
4.8a-c
5.4a-c
5.7a-c
8.3b-d
9.6cd
12.2d
1 Tomatoes harvested July 28, Aug. 3, 10,
and 17.
2 Means followed by the same letter do
not differ significantly at the 0.05 level (95
times out of 100).
3 This material applied every 2 weeks,
others applied 7 times at weekly intervals
beginning June 30.
1965 Experiments. Results from the
1965 Cullman experiment where 18 in-
secticidal treatments were evaluated for
effectiveness against the tomato fruit-
worm on trellis tomatoes are summarized
in Table 4. As previously indicated,
treatments were purposely delayed until
a fruitworm infestation developed and
the worms were never brought under
control (Table 4). Azodrin, GS-13005,
toxaphene+TDE, GC-6506, and carbaryl
were the only materials affording a de-
gree of control that was significantly
better than that of the untreated check,
based on percentage of damaged to-
matoes. Furthermore, only Azodrin-
treated plots yielded significantly fewer
damaged tomatoes than those treated
only with maneb. Fruitworms destroyed
market value of about 75 per cent of
tomatoes where no treatment was ap-
plied. Damage was approximately 50
per cent in plots treated with the more
effective insecticides. Yield of market-
able tomatoes ranged from 30.5 pounds
in the untreated check to 80.1 pounds
in plots treated with toxaphene+TDE.
However, these differences were not sta-
tistically significant at the 0.05 level 
of
probability (95 times out of 100).
Trellis tomatoes were grown on soil
of high fertility and irrigated weekly.
The plants were quite large with heavy
vegetative growth; consequently, it was
difficult to obtain good spray coverage
although rates were increased to 60 
gal-
lons of spray material per acre. Appar-
ently poor coverage contributed, at least
in part, to inadequate fruitworm 
control
obtained in this experiment. 
Further-
more, an insect infestation once 
estab-
lished is difficult to control. These 
re-
sults show the necessity of beginning 
a
control program before damaging 
fruit-
worm populations develop.
TABLE 4. FRUITwORM CONTROL 
ON TRELLIS
TOMATOES, NORTH ALABAMA 
HORTICULTURE
SUBSTATION, CULLMAN, ALABAMA, 
1965
Active Fruit-
Treatment
1  
per worm
acre damage
Lb. Pct.
Azodrin------- 1.0 
48.9
GS-13005- 2.0 50.7
GS-13005------ 1.0 
51.8
Toxaphene+
TDE ------ 2.0+1.0 
52.2
GC-6506- 0.5 54.9
Carbaryl 2.0 55.3
Carbaryl ...... 1.0 
57.7
Virus ------------------. 100O LE 59.6
Guthion- 0.5 61.7
Toxaphene-------4.0 64.4
Maneb-------- 2.0 64.9
Toxaphene 2.0 66.
ACy-EIC ----------- 1.0 67.0
N-10,242------ 1.0 67.3
TDE 1.0 68.2
Endosulfan---- 1.0 69.2
Naled- 2.0 69.6
Virus 100LE 73.4
Virus 10LE 73.4
Untreated
Check------- 0 74.7
LSD 0.05 15.7
Un-
damaged
tomatoes
per plot
2
Lb.
61.23
53.85
55.19
80.06
56.19
49.38
37.90
68.84
50.15
43.17
54.06
33.63
42.03
47.44
34.68
37.67
27.91
35.58
34.25
30.51
NS
1 Insecticides applied with 2 pounds
maneb per acre on Sept. 2, 8, 15, 20, 
27,
Oct. 1, 4, 11, and 18. N-10,242 was not
applied after Sept. 20 and GS-6506 
after
Oct. 4.
2Tomatoes harvested nine times from
Sept. 7 to Oct. 18.
[5 ]
TABLE 5. FRUITWORM CONTROL ON GROUND
TOMATOES, CHILTON AREA HORTICULTURE
SUBSTATION, CLANTON, ALABAMA, 1965
Active
Treatmentl per
acre
Lb.
Carbaryl .. 2.0
Toxaphene 4.0
TDE .......... 1.0
Carbaryl ....... 1.0
Endosulfan .... 1.0
Toxaphene+
DDT ....... 2.0+
Naled 2.0
Virus 100L
Maneb ........ 2.0
Untreated--- 0
Fruit- 
Un-
worm 
damaged
damage
2 
tomatoes
per plot
Pct. Lb.
3.1a 50.5
3.5a 48.0
4.1a 46.8
4.5a 44.9
4.8a 48.2
1.0 6.0a
6.2a
E 13.9b
17.4b
18.6b
53.8
47.1
41.2
50.3
32.0
1 All materials applied with 2 pounds
maneb per acre June 9, 17, 23, July 1 and 8.
2 Tomatoes harvested for infestation de-
terminations and yield data June 22, July
1, 8, and 15; means followed by the same
letter do not differ significantly at the 0.05
level (95 times out of 100).
Summarized results of insecticidal per-
formance on ground tomatoes at Clanton
are presented in Table 5. All materials
evaluated, except the fruitworm virus,
afforded a significant degree of fruit-
worm control based on percentage of
damaged tomatoes when compared with
the maneb and untreated checks. How-
ever, ther, there were no significant differences
among treatments in yield of marketable
tomatoes. Plots treated with maneb alone
yielded as many marketable tomatoes as
plots treated with an effective insecti-
cide plus maneb.
1966 Experiments. Results from two
experiments conducted at Cullman are
presented in Tables 6 and 7. Fruitworm
infestations were quite low on Roma
884 variety tomatoes. As given in Table
6, only 6.5 and 9.6 per cent of the to-
matoes were damaged in the untreated
and maneb checks, respectively. All in-
secticides evaluated in No. I experiment
significantly reduced the percentage of
damaged tomatoes (Table 6). Differences
in yield of marketable tomatoes were
not significant at the 0.05 level.
Results from the No. 2 experiment at
Cullman in which five experimental in-
secticides were evaluated for fruitworm
control are given in Table 7. Insect
damage was very light in this experi-
ment. Only 4 per cent of the tomatoes
were damaged in the untreated plots;
TABLE 6. FRUITWORM CONTROL ON GROUND
TOMATOES, NORTH ALABAMA HORTICULTURE
SUBSTATION, CULLMAN, ALABAMA, 1966
(EXPERIMENT No. 1)
Un-
Active Fruit- 
damaged
Treatment
1  
per wormdmae
acre 
damage
2 
tomatoes
S P 
per plot
Lb. Pct. Lb.
TDE
Toxaphene+
TD E ---------
Toxaphene+
TDE .....
Toxaphene ..
Carbaryl ....
Untreated ...
Maneb .....
1.0 1.9a 65.89
2.0+1.0 2.1a
1.0+0.5
2.0
1.0
0
2.0
2.6a
3.Oa
3.5a
6.5b
9.6b
72.72
76.20
59.10
71.35
55.43
64.27
1 All insecticides applied with 2 pounds
maneb per acre July 7, 13, 18, 28, and
Aug. 8.
2 Tomatoes harvested July 20, 26, Aug. 3,
9, and 16 for infestation determinations and
yield data; means followed by the same
letter are not significantly different at the
0.05 level (95 times out of 100).
TABLE 7. FRUITWORM CONTROL ON GROUND
TOMATOES, NORTH ALABAMA HORTICULTURE
SUBSTATION, CULLMAN, ALABAMA, 1966
(EXPERIMENT NO. 2)
Active
Treatment
1  
per
acre
Lb.
Her. 9007 +
Toxaphene ....2.0+,S
Endosulfan ........- 1.0
Azodrin 1.0
N-10,242 ...... 1.0
SD 8447 ...... 1.0
GS-13005 ..........- 1.0
Untreated -- 0
P= 0.05
Un-
Fruit- damaged
damage
2 
per plot
Pct. Lb.
3.0
3.3
3.7
3.8
3.9
4.2
4.0
NS
82.60
84.13
65.62
78.51
95.68
73.34
75.27
NS
1 Insecticides applied with 2 pounds
maneb per acre July 18, 28, and Aug. 8.
2 Tomatoes harvested July 26, Aug. 5, 10,
and 16 for infestation and yield data.
[6]
2.0
TABLE 8. FRUITWORM CONTROL ON GROUND
TOMATOES, CHILTON AREA HORTICULTURE
SUBSTATION, CLANTON, ALABAMA, 1966
Treatment
1
TDE+Maneb .....
Toxaphene+Maneb
Toxaphene+TDE+
Maneb- -
Carbaryl+Maneb ..
Maneb check- ....
Un-
Active damaged
per acre tomatoes
per acre
2
Lb. Lb.
1+2 9472a
4+2 9200a
2+0.5+2
2+2
2
7767ab
6150b
2387c
1 Materials applied Sept. 14, 20, 26, and
Oct. 3.
2 Tomatoes harvested Oct. 10 and 
17;
means followed by the same letter do 
not
differ significantly at the 0.05 level (95 times
out of 100).
consequently, no significant differences
were detected in percentage of fruit-
worm damage or yield of marketable
tomatoes among the treatments. Treat-
ment with Hercules 9007+toxaphene
was highly toxic to the plants. This was
not reflected in total yield since treat-
ment was not begun until most of the
fruit was set.
Fruitworm damage was quite severe
on a fall crop of ground tomatoes at
Clanton and yields were low on plots
receiving only a fungicide (Table 8).
All insecticidal treatments resulted in
significant increases in yield of undam-
aged tomatoes. A four-fold increase in
yield was obtained with effective fruit-
worm control. Plots treated with TDE
or toxaphene at 1 and 4 pounds per
acre, respectively, yielded more than
9,000 pounds of undamaged tomatoes
per acre, whereas plots receiving no in-
secticides yielded only 2,387 pounds of
undamaged tomatoes. Yield of undam-
aged tomatoes from plots treated with
TDE or toxaphene at indicated rates
were significantly greater than from 
plots
treated with carbaryl. A moderate 
to
heavy aphid infestation developed 
in the
carbaryl-treated plots and this may have
accounted for some of the differences 
in
yield. All plots in the experiment 
re-
ceived the same treatment, maneb, 
for
disease control, and this could not 
be
considered as a variable.
SUMMARY
The tomato fruitworm was 
the most
important insect pest of tomatoes 
during
a 3-year study at Cullman and 
Clanton.
Results from eight field experiments 
re-
vealed that the fruitworm could 
be ef-
fectively controlled with weekly applica-
tions of recommended insecticides, 
car-
baryl, toxaphene or TDE, 
applied as
dusts or sprays. Other insecticides 
that
showed some promise in controlling 
the
insect included Azodrin, Endosulfan,
GC-6506, GS-13005, and Thuricide 
90T.
Control was more effective 
when treat-
ment was begun at bloom 
or early fruit
set. No acceptable degree 
of fruitworm
control was obtained with any 
of 18 in-
secticides on trellis tomatoes when 
treat-
ments were delayed until an infestation
developed.
Weekly applications of an effective 
in-
secticide and fungicide did not signifi-
cantly increase tomato fruit 
set as com-
pared with applications of a fungicide
alone under low fruitworm 
damage.
Tomato yield was generally lower 
in
plots receiving no treatment 
and yield
reduction appeared to result from 
a lack
of disease control in several tests 
when
insect damage was light.
Fruitworm damage was heavier 
in late
summer and fall tomatoes, and 
effective
control of this insect resulted 
in a four-
fold increase in yield when damage 
was
heavy.
[7]