Belle Glade AREC Mimeo Report EV-1972-5 May, 1972
Evaluation of Aluminum Foil-Oil-Insectic d1da i1 LIBRARY
Combinations In Controlling the Spread of pepperr Viruses
T. A. Zitter, H. Y. Ozaki, and H. J. Janes dUN 2 9 972
INTRODUCTION I.F.A.S. Univ. of Florida
Recent reports have been published on the use of aluminum foil and oil
sprays to repel. and deter aphid movement and transmission of plant viruses. To
our knowledge both methods have not been used simultaneously. Because of the
seriousness of the pepper virus problem in south Florida, experiments were conduct-
ed to determine if these approaches alone or in combination with insecticides could
afford some measure of control. At the outset it was realized that this approach
might not prevent a plant from becoming infected, but instead could delay virus
spread and thus increase the chances of obtaining a good yield.
Experiments were conducted during the winter months of 1970-71 and 1971-72
at the Morikami Farm, Delray Beach. Commercial pepper growers in the area suffered
severe losses during both of these periods, indicating that heavy aphid pressure
existed during both experiments.
MATERIAL AND METHODS
The 1970-71 experiment. Each plot consisted of two beds, 6 feet wide and 20
feet long with two rows of pepper per bed. Thus each replicate consisted of 80
feet of row. The experimental design was a randomized complete block with four
replications. Essentially no windbreaks were present. Cultural practices were
patterned after those recommended by the Agricultural Research Center, (Ft. Pierce)
Morikami Farm, Delray Beach, with the plots receiving routine fungicide and insec-
ticide sprays on a weekly basis.
The four treatments were as follows:
(1) Check which received no treatment other than the routine sprays.
(2) 1% oil spray (light-medium Volck Oil) applied twice weekly at the
rate of 50 gal/acre with a knapsack mist blower (Solo Motors, Inc.).
(3) Aluminum foil bed mulch (Anaconda Co.).
(4) Aluminum foil plus oil spray.
The Early Calwonder peppers were direct seeded on November 19, 1970, and the
aluminum foil was placed over the beds on December 23. A reservoir-equipped,
water-pan aphid trap and a pair of sticky board traps were situated next to the
plots to monitor aphid flights. These were checked on a weekly basis.
The 1971-72 experiment. Certain modifications were made during the second
year of testing. The experiment consisted of six treatments in a randomized com-
plete block design with three replications. Each plot consisted of one bed, 6
feet wide and 20 feet long with two rows of pepper per bed, thus giving 40 feet
of row per replicate.
/ Assistant Plant Pathologist, University of Florida, IFAS, AREC, Belle Glade;
Associate Horticulturist, ARC (Fort Pierce), Morikami Farm, Delray Beach;
and Assistant Entomologist, AREC, Belle Glade, Fla.
Treatments were as follows:
(1) Orthene insecticide (Chevron Chemical) at the rate of 1 lb. AI/acre
applied once weekly.
(2) Orthene added to a 1% oil spray (6E, Sun Oil Co.).
(3) Orthene added to a 1% oil spray plus aluminum foil bed mulch.
,(4) 1% oil spray plus aluminum foil bed mulch.
.(5) Orthene plus aluminum foil bed mulch.
(6) Untreated check.
All spray treatments were applied weekly at the rate of 50 gal/acre with
a knapsack mist blower. All treatments received a routine fungicide spray on
a 3 to 5 day spray schedule. Other practices were the same as those followed
during the 1970-71 experiment. The Early Calwonder peppers were seeded on Novem-
ber 22 and the aluminum foil and the first sprays were applied on December 17.
The 1970-71 experiment. The cool weather which occurred during the first 3
j~'ilchs oft"171 adversely aErocted those plants receiving the oil spray treatment.
This was particularly true in treatment 2 where a total of 177 plants out of ap-
proximately 500 were lost, with the dead plants most noticeable after a January
freeze. This compared with 47 plants lost in treatment 4. Apparently the
aluminum foil in treatment 4 predisposed the plants or modified the harmful af-
fects of the oil-low temperature interaction. Previous testing had showed that
the plants were not harmed by the oil sprays under warm growing conditions.
The first virus infected plants were found in the plots on January 14, which
coincided with the first big aphid flight (Table 1). The first of three virus
readings was made 2 weeks later and largely reflect the results of this flight
(Table 2). All treatments showed about the same amount of infection. However, by
the second virus reading the trend had been established and this persisted to the
end of the experiment. The oil plus foil treatment showed the least amount of
virus infection and the check plots the most.
The superiority of the oil plus foil mulch plots was clearly shown in the
yield data (Table 3), as this treatment was significantly better in total, U.S.
Fancy and U.S. No. 1 categories.
The 1971-72 experiment. The 1971-72 experimental period was characterized
by warm weather with most of the minimum-maximum daily temperatures ranging from
60 to 80 F. Migrant aphid flights in the test plots closely followed the condi-
tion in growers fields. Maximum flights occurred in mid-December with no signifi-
cant peaks thereafter.
No plant loss or significant burning was noted in plots receiving the oil
treatment. Aphid colonization was noted for treatments 4 and 6 which did not re-
ceive an insecticide (Table 4). In the case of treatment 4 the colonization
occurred on the upper leaf surface, presumably because the aphids avoided the
shiny surface below. Observations indicated also that more pod'drop due to pep-
per weevil injury occurred in the unsprayed check.
Essentially the six treatments could be divided into two groups, those re-
ceiving aluminum foil and those without (Table 4). Orthene or Orthene plus oil
without aluminum foil did not significantly delay the virus. However, the addi-
tion of aluminum foil to these treatments resulted in 23 to 39% less virus at the
March 17 reading. Yields were not significantly different at the 5% level although
the increase in total yield for the aluminum mulch treatments approached signifi-
cance at the 5% level (Table 5).
Although the two growing seasons during which the experiments were conducted
were extremely different, the common denominator remained the presence of suf-
ficient migrating aphids carrying virus to cause a high percent of infection.
With the exception of treatment 4 in 1971, the use of oil sprays alone or in com-
bination did not significantly improve the delay in virus or increase in pepper
yields. The particular set of conditions that made the oil spray plus aluminum
foil so effective in 1971 did not exist during the second year of testing and
probably could not be repeated. Although insecticides did prevent aphid coloniza-
tion, weevil and worm injury, by themselves, they were not effective in delaying .
virus spread as seen from results with treatment 1 in 1971 and 1972.
Thus aluminum foil mulches contributed the most to delaying virus development
and increasing total yields. VWhether this repelling action would be as effective
when performed on a larger scale is not known. The use of mulch to reduce ferti-
lizer leaching also probably contributed to the higher yields. Because of the
increased use of bed mulches in commercial operations, the effectiveness of black
plastic and aluminum painted covers in delaying virus spread should be investigated
Two years of testing at the Horikami Farm in Delray Beach during epidemic
virus conditions revealed that aluminum foil treatments on a small plot basis
were by far the best control measure for the pepper virus problem. Generally
speaking, the addition of oil and insecticide sprays did not significantly improve
the overall action of the aluminum foil. Increased yields for the mulch treatments
were probably due to both virus delay and reduced fertilizer leaching.
Table 1. Winged aphid populations monitored by water-pan and
at Morikami Farm during the 1970-71 experiment.
Direction of sticky board
H S E 1
sticky board traps
Table 2. Effect of aluminum foil and
oil sprays on virus development
% virus infection
1 Check 6.3 25.9 100
2 Oil alone 7.3 9.0 89.1
3 Foil alone 5.2 16.9 95.9
4 Oil F Foil 4.1 5.8 63.0
Table 3. Effect of aluminum foil and oil sprays on pepper yield,
ilorikami Farm, 1971.
No. lbs. from four harvests
Total U.S. Fancy U.S. No. 1
2 Oil alone
3 Foil alone
4 Oil & Foil
l- Means followed by same letter are not significantly different at
the 1% level.
Table 4. Effect of various treatments on aphid colonization and virus
development during 1972.
Mean number aphids/leaf % virus infection
Treatment Jan. 6 Jan. 28 Jan. 28 liar. 17
1 Orthene 0 0 1 36b 2/ 83c
2 Oil + Orthene 0 0 / 24ab 79bc
1/ 13a ab
3 Oil+Orthene+Aluminum 0 0- 13 52
4 Oil + Aluminum 0 39 8a 52ab
5 Orthene + Aluminum 0 0/ 13 44
6 Check 2.6 28 27b 75bc
SAdditional inspection over the, plots revealed the presence of alates.
- Means followed by same letter are not significantly different at the 5%
level using Duncan's Multiple Range Test.
Table 5. Effect of various treatments on pepper yield
Iorikami Farm, 1972.
io. Ibs. from seven harvests
Total U. S. Fancy Fancy & U.S. No. 1
Includes cull peppers.