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_( /-7 NORTH FLORIDA RESEARCH AND EDUCATION CENTER Ir'. -
Quincy, Florida iar
AGRICULTURAL RESEARCH AND EDUCATION CENTER
Live Oak, Florida
Quincy NFREC Research Report NF-88-12
Chemical Control of Insects Attacking Flue-Cured Tobacco in 1988__--
William B. Tappan, Entomologist, Quincy,-and
Jimmie R. Rich, Nematologist, Live Oak
MATERIALS AND METHODS
Nine chemical foliar spray treatments were field tested on Northrup King
K-326 flue-cured tobacco for insect control, phytotoxicity, effect on crop
yield and value, and insect resistance to certain treatments. Formulations,
number of applications, and dosage of active ingredients per acre per applica-
tion are presented in Table 1.
The dates treatment applications were made are given in a footnote in
Tables 1 through 6. Spray treatments were applied at 14-day intervals with a
tractor-mounted CO2-pressurized sprayer with one hollow-cone nozzle over each
row and one hollow-cone nozzle on each side of the row. The three Tee-Jet D3-
25 nozzles per row were designed to deliver approximately 26 gallons of spray
per acre at 60 p.s.i. and 4 m.p.h.
Treatments were replicated three times in complete randomized blocks.
Each plot was two rows wide, and was separated by a 5-foot vacant alley or
buffer zone between plots within a block. The rows were 40 feet long and 3.67
feet apart within plots. Both rows served as the experimental plot for insect
counts, phytotoxicity ratings, crop yield, crop value, and insect resistance
to certain treatments. Each row contained 24 to 25 plants set on approxi-
mately 19-inch centers. Alleys between blocks of plots were 20 feet wide.
The test was located northeast of the barn area of the Center.
All cultural practices in preparing the test area for planting were per-
formed in the usual manner. Beds for planting were prepared and fertilizer
applied in late February. The tobacco was transplanted on March 21, 1988, and
hand-topped on May 31. A sucker control, Royal-Tac, was applied at 2 gallons
per acre on June 2, followed by hand suckering on June 9, and an additional
application of MH-30 at 1.5 gallons per acre on June 10.
Green peach aphid counts were made from natural infestations beginning on
April 25 (pretreatment count), and succeeding counts followed at 14-day inter-
vals. All counts were made by counting the number of live alate and apterous
aphids on four leaves three inches or longer down from the bud. Five marked
plants equidistant from each other in each of the experimental rows were
counted.
Counts of tobacco budworm and tobacco hornworm were made from natural
infestations on April 25 (pretreatment count), and all succeeding counts were
made on the same dates as aphid counts. Each plant in each plot that had at
least one larva and the characteristic feeding injury of the species was
counted as a damaged plant.
A rating of redlegged grasshopper, Melanoplus femurrubrum (DeGeer), damage
was made on June 8. The rating was based on a scale of 0 to 10 with 0 = none
and 10 = 100% of the foliage showing some grasshopper damage.
Visual phytotoxicity ratings were begun on April 25 (pretreatment count),
and all succeeding counts were made on the same dates as aphid counts. Plots
were rated according to severity of phytotoxicity observed. The readings were
based on the following rating system:
0 = None
1 = Slight leaf spotting or chlorosis
2 = Moderate leaf spotting or chlorosis
3 = Heavy leaf spotting or chlorosis with some necrosis
4 = Severe leaf spotting or chlorosis with considerable necrosis
Four leaf primings or harvests were made during the crop season for evalu-
ation of crop performance on June 7, 21, July 5, and 25. Yield was calculated
in pounds per acre from the total weight of cured leaves from each treatment
replication. The crop value or dollar return per acre was obtained by multi-
plying the yield in pounds per acre by the return in cents per pound of cured
leaf. The value per pound was based upon the price of the various grades of
tobacco.
The treatment data were subjected to an analysis of variance, and the
least significant difference (LSD) and Duncan's multiple range tests were
applied to all means to obtain statistical comparisons for data interpreta-
tion.
Rainfall data collected for the term of the experiment are expressed in
inches as follows:
March April May June July
21 0.35 7 0.05 2 2.00 6 0.12 1 0.14
28 0.72 12 0.10 11 0.40 7 0.12 5 1.00
Total IT.7 13 0.43 16 0.17 8 0.11 11 0.37
20 0.45 25 0.23 28 0.42 12 0.07
27 0.22 26 0.86 Total 0.77 14 0.15
Total 1.25 27 0.06 19 0.30
Total 3.72 21 0.68
25 0.31
Grand Total = 9.83 inches Total 3.02
RESULTS AND DISCUSSION
The experimental tobacco was planted in late March in order to avoid
freezing temperatures as experienced during the past two years. However, no
severe freezes occurred to affect planting. Insect infestations appeared
about the same time as in 1987, but were somewhat less numerous initially.
The green peach aphid population was smaller initially, but was considerably
larger at the peak on June 8. The aphid population was primarily the red
form. Although populations of aphids reached larger numbers at the peak than
in 1987, PVY infestations were not as large. Only 12 percent of the plants
exhibited symptoms of PVY infection on May 11. The tobacco budworm population
was slightly less numerous initially than in 1987, and never reached as large
a level at the peak of the population. The drought weather conditions may
have had a significant impact on pupal eclosion, since the population declined
from the initial count throughout the remainder of the growing season. There
is no doubt that the drought had an effect on the budworm population, since
the population peaked on the pretreatment count and declined for the remainder
of the test period. The unusual decline is the first time in 33 years that it
has started with the pretreatment count. Usually the decline is precipitated
by topping of the plants at or near the buttoning stage of plant development.
The budworm decline cannot be attributed to cold weather as the winter was
rather mild with no severe prolonged freezes. Populations of the tobacco
hornworm were considerably smaller than in 1987. The first infestation in the
field was not noted until May 25, which was almost three weeks later than in
1987. The peak in hornworm damaged untreated plants occurred on June 8, and
never exceeded that peak for the remainder of the growing season. The peak in
damaged hornworm plants in 1988 was 42.4% smaller than the peak in 1987. The
predaceous wasp that was observed in large numbers in 1986 was absent from the
test plots in 1988. No doubt that the drought weather adversely influenced
the hornworm population much as it did the budworm population. However,
mature 5th instar hornworm larvae were rare on infested plants, which was
probably an association of the small population that was present. Rainfall
during the growing season was 9.67 inches less than that for 1987. The rain-
fall was the smallest amount recorded since 1981, when 9.29 inches occurred.
Yield of untreated tobacco in 1987 was 2,255 pounds per acre compared to 2,871
in 1988, which indicated that the small populations of budworms and hornworms
were responsible for the increase in yield. This marks the 20th year in suc-
cession that no control data have been obtained on the cabbage looper because
populations on the crop have been nonexistent.
Green peach aphids began building populations on field plants on April 25
(pretreatment count), which were smaller than in 1987. Populations increased
rapidly on untreated plants until June 22, when populations began declining.
The populations at the peak level on June 8 were 1.3 times larger than the
peak level on June 3, 1987. The favorable weather conditions in 1988 enhanced
aphid reproduction, which resulted in the large populations. Populations of
aphids on the last count on July 6 were located on new sucker growth, but did
not reach as large a level in those locations as in 1987. (See Table 2.) On
June 8, when populations were the largest on the untreated tobacco checks, all
treatments gave significant (P = 0.05) control, but the control obtained with
all three dosages of F-7869 would not be commercially acceptable. Any treat-
ment on June 8 that had counts in excess of 1,000 would not be acceptable to
the grower. The data on June 8 indicated that both dosages of Lannate were on
the border of being unacceptable. Although there was no statistical differ-
ence between Capture, Lannate, and Orthene, all dosages of Capture and Orthene
were numerically superior to Lannate for aphid control. The yield and dollar
return data in Table 6 indicated that the aphid may have contributed to a re-
duction in both parameters, especially in F-7869 treated tobacco.
Budworm populations were smaller initially than in 1987, and never
attained as large a level at the peak on April 25, 1988. The population
peaked about a month earlier than in 1987, and began declining prior to
topping, which was an unusual phenomenon. A similar pattern of population
decline occurred in 1987. The population decline in past observations (prior
to 1937) has been consistently associated with topping, which was related to
removal of the inflorescence and seed heads the preferred feeding sites of
the budworm. Weather conditions were not considered a factor in the 1987
decline, but undoubtedly were a major cause of the 1988 decline. (See Table
3.) Using the May 11 count for treatment comparison, all treatments gave sig-
nificant control. Orthene at 2.259 lbs. AI/A. was numerically superior to all
other treatments. However, owing to the unusual decline in budworm popula-
tions, accurate comparison of differences between treatments was impossible.
The lack of heavy budworm infestations contributed to larger yields of cured
tobacco than in 1987. (See Table 6.)
The hornworm population began to increase on the tobacco on May 25, which
was about three weeks later than in 1987. No doubt that the drought weather
conditions adversely affected hornworm pupal eclosion, which was responsible
for the lateness of infestations. Population levels on the untreated tobacco
checks never reached as large a level as in 1987 at any time during the
growing season. (See Table 4.) On June 8, all treatments gave significant
control, with both dosages of Capture being numerically superior to the other
treatments. Some yield and dollar return loss was probably caused by the
hornworm particularly in the untreated check tobacco. (See Table 6.)
Only Lannate at both dosages caused any detectable phytotoxicity. The
injury was evident following the first spray application. Chlorosis of the
lamina was present in the middle and top of the plants and persisted until
June 22. As the leaves matured during the latter part of the growing season
and were removed by harvesting, the phytotoxicity disappeared. (See Table 5.)
The phytotoxicity had no apparent adverse effect on yield or dollar return.
(See Table 6.)
Redlegged grasshopper, Melanoplus femurrubrum (DeGeer), infested the
tobacco in large numbers, and caused considerable feeding damage. On June 8,
all treatments except Lannate at 0.701 lb. AI/A. gave significant control of
the grasshopper. Capture at 0.113 and Orthene at 2.259 lbs. AI/A. were numer-
ically superior to the other treatments. The grasshopper had no significant
effect on yield or dollar return. (See Table 6.)
Yield in the untreated tobacco checks was 616 lbs./A. (27.3%) larger than
in 1987, which was probably due to the smaller than usual budworm and hornworm
populations. Dollar return in the untreated tobacco checks increased $798
(26.7%) as compared to that in 1987 indicating that insects were not signifi-
cantly detrimental to the crop in 1988. The best yield from treated tobacco
was 484 lbs./A. (15.2%) larger than in 1987, and best dollar return was $797
(18.7%) larger. The increase in dollar return was primarily due to the
increased yield, since the return per pound averaged $0.06 less in 1988 ($1.38
versus $1.32). (See Table 6.)
F-7869 was tested in the field for the first time, and compares favorably
with Capture and Orthene for control of the budworm, hornworm, and redlegged
grasshopper. However, the compound did not give effective control of the
aphid, which is a disadvantage when compared to both Capture and Orthene.
NFREC, Quincy and AREC, Live Oak, Florida
Table 1. Foliar Treatments Applied for Insect Control on Flue-Cured Tobacco (K-326) 1988.
Gals. Lbs. AI
Number per Acre per per Acre per
Treatmenta'b Applications Application Application
Lannate, 0.29%S (1.8 lbs./gal. L) 6 28.9 0.701
Lannate, 0.58%S (1.8 lbs./gal. L) 6 28.1 1.362
Orthene, 0.5%S (75% SP) 6 28.2 1.163
Orthene, 1.0%S (75% SP) 6 27.4 2.259
Capture, 0.027%S (2.0 Ibs./gal. EC) 6 27.2 0.062
Capture, 0.051%S (2.0 lbs./gal. EC) 6 27.1 0.113
F-7869, 0.0236%S (0.42 lb./gal. EC) 6 23.8 0.045
F-7869, 0.0472%S (0.42 lb./gal. EC) 6 24.5 0.093
F-7869, 0.0708%S (0.42 lb./gal. EC) 6 24.2 0.146
Check (Untreated)
aEC = Emulsifiable concentrate, L = Liquid concentrate, S = Spray, and SP = Soluble powder.
Sprays were applied on 4/27, 5/11, 5/25, 6/8, 6/22, and 7/6/88. Tobacco was transplanted on 3/21/88, and
harvested on 6/7, 6/21, 7/5, and 7/25/88.
NFREC, Quincy and AREC, Live Oak, Florida
Table 2. Mean Number of Green Peach Aphids per Plot of Flue-Cured Tobacco (K-326) 1988.
Aphid Countsb Mean
Lbs. AI/Acre/
Treatment 4/25c 5/11 5/25 .6/8 6/22 7/6d Application
Lannate, 0.29%S (1.8 Ibs./gal. L) 89a 94a 290a 881a 579a 83abc 0.701
Lannate, 0.58%S (1.8 lbs./gal. L) 201a 23a 35a 707a 203a 26ab 1.362
Orthene, 0.5%S (75% SP) 57a la 2a 4a 3a 20ab 1.163
Orthene, 1.0%S (75% SP) 107a la la 54a 38a Oa 2.259
Capture, 0.027%S (2.0 lbs./gal. EC) 193a 3a 3a la la Oa 0.062
Capture, 0.051%S (2.0 lbs./gal. EC) 181a la la Oa Oa Oa 0.113
F-7869, 0.0236%S (0.42 lb./gal. EC) 50a 229a 2,478b 3,715b 4,475bc 167d 0.045
F-7869, 0.0472%S (0.42 lb./gal. EC) 74a 453a 2,808b 4,648b 4,617bc 98bcd 0.093
F-7869, 0.0708%S (0.42 lb./gal. EC) 63a 238a 2,323b 3,891b 2,512ab 76abc 0.146
Check (Untreated) 221a 2,254b 5,639c 13,406c 6,893c 147cd
LSD 5% NS 935 1,089 1,461 2,586 78
LSD 1% NS 1,283 1,493 2,003 3,546 107
bSee Table 1 for more details. Sprays were applied on 4/27, 5/11, 5/25, 6/8, 6/22, and 7/6/88.
Counts were made on 10 plants per plot, totaling 30 plants in three plots. Means followed by the same
letter are not significantly different at the 5% level.
cPretreatment count. Tobacco was transplanted on 3/21/88. Plants were hand topped on 5/31/88. Sucker
control was applied: Royal Tac on 6/2 and MH-30 on 6/10/88. Plants were hand suckered on 6/9/88. Tobacco
dwas harvested on 6/7, 6/21, 7/5, and 7/25/88.
Aphids were on sucker growth.
NFREC, Quincy and AREC, Live Oak, Florida
Table 3. Mean Percent Budworm Damaged Flue-Cured Tobacco Plants per Plot (K-326) 1988.
% Budworm Damaged Plantsb Mean
Lbs./Acre/
Treatment 4/25c 5/11 5/25 6/8 6/22 7/6 Application
Lannate, 0.29%S (1.8 lbs./gal. L) 50a 17b 7b 12c 7abc 6a 0.701
Lannate, 0.58%S (1.8 lbs./gal. L) 51a llab 4ab llbc 8abc 3a 1.362
Orthene, 0.5%S (75% SP) 48a 8ab 3ab 7abc 9bc 7a 1.163
Orthene, 1.0%S (75% SP) 55a 3a lab 6abc 6abc la 2.259
Capture, 0.027%S (2.0 lbs./gal. EC) 43a llab lab la la 2a 0.062
Capture, 0.051%S (2.0 lbs./gal. EC) 59a 9ab 3ab la 4ab 2a 0.113
F-7869, 0.0236%S (0.42 lb./gal. EC) 53a 12ab lab 5ab 3ab la 0.045
F-7869, 0.0472%S (0.42 lb./gal. EC) 51a 10ab Oa 2a 5ab 5a 0.093
F-7869, 0.0708%S (0.42 lb./gal. EC) .48a llab lab 3a 3ab 3a 0.146
Check (Untreated) 61a 55c 27c 12c 12c 16b
LSD 5% NS 11 6 7 6 6
LSD 1% NS 15 8 9 8 8
bSee Table 1 for more details. Sprays were applied on 4/27, 5/11,
Counts were made on 47 to 51 plants per plot, totaling 148 to 151
the same letter are not significantly different at the 5% level.
CPretreatment count. Tobacco was transplanted on 3/21/88. Plants
control was applied: Royal Tac on 6/2 and MH-30 on 6/10/88. Plai
was harvested on 6/7, 6/21, 7/5, and 7/25/88.
5/25, 6/8, 6/22, and 7/6/88.
plants in three plots. Means
were hand topped on 5/31/88.
followed by
Sucker
nts were hand suckered on 6/9/88. Tobacco
NFREC, Quincy and AREC, Live Oak, Florida
Table 4. Mean Percent Hornworm Damaged Flue-Cured Tobacco Plants per Plot (K-326) -
1988.
% Hornworm Damaged Plantsb Mean
a Lbs. AI/Acre/
Treatmenta 4/25c 5/11 5/25 6/8 6/22 7/6 Application
Lannate, 0.29%S (1.8 lbs./gal. L) 0.0 0.0 5a 26d 32d 26c 0.701
Lannate, 0.58%S (1.8 lbs./gal. L) 0.0 0.0 3a 21bcd 24cd 14b 1.362
Orthene, 0.5%S (75% SP) 0.0 0.0 3a 24cd 23bcd 16b 1.163
Orthene, 1.0%S (75% SP) 0.0 0.0 la llabc 6ab .3a 2.259
Capture, 0.027%S (2.0 lbs./gal. EC) 0.0 0.0 Oa 2a 3a la 0.062
Capture, 0.051%S (2.0 lbs./gal. EC) 0.0 0.0 Oa la 2a la 0.113
F-7869, 0.0236%S (0.42 lb./gal. EC) 0.0 0.0 2a 9ab 12abc 10ab 0.045
F-7869, 0.0472%S (0.42 lb./gal. EC) 0.0 0.0 3a 7a 17abcd 12ab 0.093
F-7869, 0.0708%S (0.42 lb./gal. EC) 0.0 0.0 la 10abc 8abc 5ab 0.146
Check (Untreated) 0.0 0.0 12b 55e 49e 53d
LSD 5% -- 5 13 15 10
LSD 1% -- 7 18 21 13
aSee Table 1 for more details. Sprays were applied on 4/27, 5/11, 5/25, 6/8, 6/22,
Counts were made on 47 to 51 plants per plot, totaling 148 to 151 on three plots.
same letter are not significantly different at the 5% level.
CPretreatment count. Tobacco was transplanted on 3/21/88. Plants were hand topp
control was applied: Royal Tac on 6/2 and MH-30 on 6/10/88. Plants were hand sucki
was harvested on 6/7, 6/21, 7/5, and 7/25/88.
and 7/6/88.
Means followed by the
ed on 5/31/88. Sucker
ered on 6/9/88. Tobacco
NFREC, Quincy and AREC, Live Oak, Florida
Table 5. Phytotoxic Effects of Certain Insecticide Formulations on Flue-Cured Tobacco (K-326) 1988.
Mean Phytotoxicity Indicesb
Mean
LbT.h AT/Acre/
a c
Treatment 4/25 5/11 5/25 6/8 6/22 7/6 Application
Lannate, 0.29%S (1.8 lbs./gal. EC) 0.0 2.3 1.7 .0.7 0.0 0.0 0.701
Lannate, 0.58%S (1.8 lbs./gal. EC) 0.0 4.0 4.0 1.3 0.0 0.0 1.362
Orthene, 0.5%S (75% SP) 0.0 0.0 0.0 0.0 0.0 0.0 1.163
Orthene, 1.0%S (75% SP) 0.0 0.0 0.0 0.0 0.0 0.0 2.259
Capture, 0.027%S (2.0 Ibs./gal. EC) 0.0 0.0 0.0 0.0 0.0 .0.0 0.062
Capture, 0.051%S (2.0 lbs./gal. EC) 0.0 0.0 0.0 0.0 0.0 0.0 0.113
F-7869, 0.0236%S (0.42 lb./gal. EC) 0.0 0.0 0.0 0.0 0.0 0.0 0.045
F-7869, 0.0472%S (0.42 lb./gal. EC) 0.0 0.0 0.0 0.0 0.0 0.0 0.093
F-7869, 0.0708%S (0.42 lb./gal. EC) 0.0 0.0 0.0 0.0 0.0 0.0 0.146
Check (Untreated) 0.0 0.0 0.0 0.0 0.0 0.0
aSee Table 1 for more details. Sprays were applied on 4/27, 5/11, 5/25, 6/8, 6/22, and 7/6/88.
Rating System: 0 = None, 1 = Slight leaf spotting or chlorosis, 2 = Moderate leaf spotting or chlorosis, 3
= Heavy leaf spotting or chlorosis with some necrosis, and 4 = Severe leaf spotting or chlorosis with
considerable necrosis.
CPretreatment count. Tobacco was transplanted on 3/21/88. Plants were hand topped on 5/31/88. Sucker
control was applied: Royal Tac on 6/2 and MH-30 on 6/10/88. Plants were hand suckered on 6/9/88. Tobacco
was harvested on 6/7, 6/21, 7/5, and 7/25/88.
I
NFREC Quincy and AREC, Live Oak, Florida
Table 6. Effects of Certain Insecticidal Treatments on Grasshopper Damage Ratings, Yield, and Dollar Return
per Acre of Flue-Cured Tobacco (K-326) 1988.
Grasshopper ,d Yield Dollar Mean Rate
bDamage Rating Lbs./Acre d Return/Acre d Lbs. AI/Acre/
Treatment' 6/8 Mean 3 Reps. Mean 3 Reps. Application
Lannate, 0.29%S (1.8 lbs./gal. L) 6.3cd 3,666a 4,855a 0.701
Lannate, 0.58%S (1.8 lbs./gal. L) 5.0bc 3,386a 4,363a 1.362
Orthene, 0.5%S (75% SP) 3.0ab 3,668a 5,049a 1.163
Orthene, 1.0%S (75% SP) 1.3a 3,170a 4,093a 2.259
Capture, 0.027%S (2.0 lbs./gal. EC) 2.0a 3,349a 4,506a 0.062
Capture, 0.051%S (2.0 lbs./gal. EC) 1.0a 3,371a 4,418a 0.113
F-7869, 0.0236%S (0.42 lb./gal. EC) 3.7abc 3,025a 3,929a 0.045
F-7869, 0.0472%S (0.42 lb./gal. EC) 2.7ab 2,975a 3,864a 0.093
F-7869, 0.0708%S (0.42 lb./gal. EC) 2.7ab 2,987a 3,907a 0.146
Check (Untreated) 8.0d 2,871a 3,786a
LSD 5% 2.7 NS NS
LSD 1% 3.7 NS NS
aSee Table 1 for more details. Sprays were applied on 4/27, 5/11, 5/25, 6/8, 6/22, and 7/6/88.
Tobacco was transplanted on 3/21/88. Plants were hand topped on 5/31/88. Sucker control was applied:
Royal Tac 6/2 and MH-30 on 6/10/88. Plants were hand suckered on 6/9/88. Tobacco was harvested on 6/7,
6/21, 7/5, and 7/25/88.
,Rating System: 0 = None and 10 = 100% of foliage showing some damage from Melanoplus femurrubrum (DeGeer).
Means followed by the same letter are not significantly different at the 5% level.
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