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Group Title: Mimeo report - North Florida Experiment Station, University of Florida - 57-8
Title: Phytotoxicity of certain insecticides to shade tobacco seedlings in the plant bed
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Permanent Link: http://ufdc.ufl.edu/UF00073277/00001
 Material Information
Title: Phytotoxicity of certain insecticides to shade tobacco seedlings in the plant bed
Series Title: NFES mimeo rpt.
Physical Description: 5 leaves : ; 28 cm.
Language: English
Creator: Tappan, William B., 1928-
North Florida Experiment Station
Publisher: North Florida Experiment Station
Place of Publication: Quincy Fla
Publication Date: 1957
 Subjects
Subject: Tobacco -- Effect of insecticides on -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by William B. Tappan.
General Note: Caption title.
General Note: "March 28, 1957."
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00073277
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 82499348

Table of Contents
    Photoxicity of certian insecticides to shade tobacco seedlings in the plant bed
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        Page 2
        Page 3
    Data
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        Page 5
Full Text
/,O


NORTH FLORIDA EXPERIMENT STATION
QUINCY, FLORIDA

March 28, 1957
NFES Mimeo Rpt. 57-8

PHYTOTOXICITY OF CERTAIN INSECTICIDES TO SHADE TOBACCO
SEEDLINGS IN THE PLANT BED

by William B. Tappan
Assistant Entomologist

This study was undertaken in cooperation with the United States
Department of Agriculturel to determine the phytotoxic effect of certain
insecticides to shade tobacco seedlings in the plant bed.

MATERIALS AND METHODS

Plots, 3 x 5 feet in size, were sown with Dixie Shade tobacco seeds and
were located in the "bug" plant bed. The bed was enclosed with a cheese cloth
covering, which provided some degree of protection and shade for the young
seedlings.

The test consisted of 8 dust treatments and an untreated check replicated
3 times in unrandomized blocks. (See Table 1.) Three applications at one-week
intervals were made in sequence after the plants reached a height of about
2 inches. To simulate the commercial plant bed dusting program the rate of appli-
cation was gradually increased each week. The first week, 15 pounds per acre;
the second week, 30 pounds per acre; and the third week, 45 pounds per acre of
each treatment was applied to all plots. Each application was made with a
Model 415, Lowell plunger type hand duster. To contain the dust on each plot
during application, a cloth dusting hood, 3 x 5 feet, was used. The amounts of
test material used at the various rates of application were as follows:

Rate of Application Amount Used Per Plot

15 Ibs. per acre 2333 mg.
30 Ibs. per acre 4667 mg.
45 Ibs. per acre 7000 mg.

Visual phytotoxicity readings were made at 24, 48, 120, and 144 hour
intervals after each application and were based on the rating system below:

0 No injury or stunting
1 Slight injury or slight stunting
2 Moderate injury or moderate stunting
3 Heavy injury or heavy stunting
4 Severe injury or severe stunting


1Truck Crop Insect Laboratory, Quincy, Florida
Truck Crop Insect Laboratory, Quincy, Florida







NFES 57-8 cont'd.


RESULTS

All treatments with the exception of Dow-ET-14, guthion, and phosdrin
showed no adverse effects to the young tobacco seedlings. (See Table 2.)

Four percent Dow-ET-14 dust when applied at 15 pounds per acre caused
heavy injury to shade tobacco seedlings. The first symptoms of phytotoxicity
were observed 24 hours after treatment, when the leaves began drooping and cupping
downward. Damage was more apparent at the end of 48 hours, characterized by
moderate drooping of the leaves and stunting. Heavy damage was evident 120 hours
after treatment, when the leaf edges began curling and the leaf surfaces showed
moderate mottling. The leaves were heavily curled and crinkled after 144 hours.
The plants showed some signs of recovery 168 hours after treatment. However, the
insecticide was considered too toxic at the 4-percent concentration and was deleted
from further testing. Twelve days after treatment, the plants had almost fully
recovered from their damaged state. No dead plants resulted from the treatment,
and at the time of transplanting there was little evidence of phytotoxicity.
(See Table 2.)

Five percent guthion dust showed some slight symptoms of phytotoxicity
at the rates of 30 and 45 pounds per acre. Slight mottling of the leaves and
stunting of the plants was observed on all plots. (See Table 2.) These
conditions were slowly disappearing prior to transplanting. The evidence obtained
from the guthion treatments was not considered conclusive and the material has
been set aside for further study.

Application 6f 30 pounds per acre of 3 percent phosdrin dust resulted in
slight mottling after 24 hours. The condition continued 144 hours after treatment,
when a definite stunting effect was observed. Twenty-four-:hours after the
45-pound per acre treatment, severe mottling and moderate stunting were evident.
At the 144-hour interval, the leaves were crinkled, severely mottlr' and the
plants were heavily stunted. (See Table 2.)

Vegetable weevils, Listroderes costirostris obliquus (Klug.) estimated
tobe causing 1 percent damage to the untreated checks, were controlled
effectively on all treated plots.

CONCLUSIONS

Four percent Dow-ET-14 dust was highly phytotoxic at the rate of 15 pounds
per acre, and is not safe to use at that concentration in the plant bed. The
results obtained indicate that the 4-percent concentration will be harmful to
shade tobacco if used in the field.

Results with 5 percent guthion indicate that it is apparently safe to
tobacco seedlings, but should be applied with caution at rates exceeding 15
pounds per acre. Additional work is necessary for more conclusive evidence on
the phytotoxicity of this compound.

Three percent phosdrin dust at rates above 15 pounds per acre will cause
moderate to heavy injury to tobacco seedlings.








NFES 57-8 conttd.


Three percent trithion, 2 percent parathion plus 0.5 percent endrin,
and 2, 3, and 5 percent thiodan dusts are considered safe at weekly rates
not exceeding 45 pounds per acre.

All formulations tested apparently will give effective control of
light infestations of vegetable weevils.




NFES
3/28/57
100 cc








NORTH FLORIDA EXPERIMENT STATION
QUINCY, FLORIDA
Table 1. Insecticides applied to shade tobacco seedlings for phytotoxicity studies.


Formulation Formulator Source Diluent

5% Guthion dust U.S.D.A. Chemagro Corporation Sterilized tobacco dust
25% wettable powder
3% Phosdrin dust U.S.D.A.. Shell Chemical Company Pyrophyllite (Pyrax ABB)
10% wettable powder
2% Parathior plus U.S.D.A. Diamond Black Leaf Company Sterilized tobacco dust
0.5% Endrin dust 15% and 25% wettable powder
respectively
2% Thiodan dust U.S.D.A. Niagara Chemical Division Sterilized tobacco dust
25 % wettable powder
3% Thiodan dust U.S.D.A. Niagara Chemical Division Sterilized tobacco dust
25% wettable powder
5% Thiodan dust U.S.D.A. Niagara Chemical Division Sterilized tobacco dust
25% wettable powder
3% Trithion dust N.F.E.S. Stauffer Chemical Company Sterilized tobacco dust
25% wettable powder
4% Dow-ET-14 dust N.F.E.S. Dow Chemical Company Sterilized tobacco dust
25% wettable powder








NORTH FLORIDA EXPERIMENT STATION
Quincy, Florida

Table 2. Phytotoxicity of certain insecticides to shade tobacco seedlings in the plant bed.


: PiTytotoxccity Ratingu (Ave. 3 plots)
: 15 lbs. per acre : 30 lbs. per acre___ 45 lbs. _per acre __
Treatment :24 hr. 48 hr. 120 hr. 144 hr. 24 hr. 48 hr. 120 hr. 4 hr 120 hr. 144 hr.


5% Guthion

3% Phosdrin

2% Parathion
plus O.5% Endrin

2% Thiodan

3% Thiodan

5% Thiodan

3% Trithion

4% Dow-ET-14

Check
(Untreated)


0

0

0


0

0

0

0

1


O


0

0

0


0

0

0

0

2


0


Deleted from tests


* See under Materials and Methods.


0 0


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