Control of insects on growing tobacco plants of the flue-cured type


Material Information

Control of insects on growing tobacco plants of the flue-cured type
Physical Description:
9 p. : ill. ; 26 cm.
Shands, W. A
United States -- Bureau of Entomology and Plant Quarantine
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:


Subjects / Keywords:
Flue-cured tobacco -- Diseases and pests -- Control   ( lcsh )
Insect pests -- Control   ( lcsh )
federal government publication   ( marcgt )
non-fiction   ( marcgt )


General Note:
Caption title.
General Note:
"E-499 ; May 1940."
Statement of Responsibility:
by W.A. Shands, Norman Allen, and J.U. Gilmore.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030269956
oclc - 778706854
System ID:

Full Text




By W. A. Shands, Norman Allen, and J. U. Gilmore, Division
of Truck Crop and Garden Insect Investigations

The most important insect pests of the growing tobacco pli;..t of the
flue-cured type are the tobacco flea beetle (Epitrix parvul.a (F.)), the
tomato and tobacco worms (Protoparce sexta (Johan.) and P. .1 inf-'.jn*I,]it a
(Haw.)). and the true and false tobacco budworms (Heliothis virescens (F.)
and H. armigera (Hbn.)).


In the plant beds.--Whenever possible, select a new site for the
plant bed. If this is impractical, avoid covering the old bed site with
stable manure or plant refuse during the summer months. Burn or steam
the bed areas prior to planting so as to destroy any insects that are in
the upper layers of the soil. Use boards for the side walls and see that
these are well banked with soil outside and fitted tightly at the corners
so as to prevent entry of insects. Use a good grade of cheesecloth con-
taining at least 25 strands per linear inch for the bed cover. See that
the cover extends well over the tops of the side v.all., and is fastened
securely on the outside. Growers will find that the tightly constructed
plant bed will eliminate to a large extent the flea beetle djinage to very
young plants frequently experienced in loosely constructed plant beds.

In the field.-Destroy the tobacco stalks immediately after harvest.
This will eliminate an important food supply of several kinds of injurious
insects of tobacco. Deep and thorough fall plowing, .,here agronomic con-
ditions permit, followed by a suitable cover crop, will destroy many insects
and render the fields less suitable as hibernation quarters for insect


The tobacco plant is subject to injury by the flea beetle from the
time the seeds germinate until the crop is harvested. The adult can,

2 -

and frequently does, completely destroy small plants in beds. As the plants
grow and beetle larvae develop and become more numerous, their injury to
the plant roots, together with injury by the adults to the plant tops,
causes a retardation in the growth rate and also weakens the plant for trans-
planting. Recent studies have also shown that the tobacco plant bed is an
important breeding ground of these beetles, particularly during the early
part of the season, because from the plant bed they can emerge and move to
tobacco growing in the field. Besides protecting the tobacco plants before
transplanting them he grower should c'estroy all the plants in the beds as
soon as transplanting has been completed in order to remove these plants as
a source of breeding material for the flea beetle.

Newly transplanted tobacco is especially susceptible to injury from
feeding by the adult beetle on the plant foliage and by the larvae on the
roots and in the stems. The adult and larval stages of this beetle are
capable of completely destroying the stand under certain conditions. Even
though the plant may not be destroyed it may suffer permanent injury or be
weakened to such an extent that its rate of growth will be materially re-
tarded. The control of even light infestations on newly set plants should
serve to reduce the number of flea beetles that would deposit eggs from which
later generations of the insect can be built up.

Severe beetle injury to the foliage of the growing tobacco plant
reduces both yield and quality. In instances of extreme injury the leaves
cannot be properly cured, and as a result that portion of the crop becomes
a total loss.


In Plant Beds

Flea beetles can be controlled by dusting with a rotenone-bearing dust
or with a mixture of paris green and lead arsenate. Either of these dusts
may be used on the young plants in the beds, but, because of the objection-
able residue, the paris green-lead arsenate mixture is not recommended for
use on the growing crop in the field.

Rotenonp-bearing dusts.--Dust mixtures containing 1 percent of rote-
none, prepared with cube or derris, should be applied at the rate of one-half
pound per 100 square yards of plant bed with a rotary type, han.d-operated
duster. The application should be repeated about every 4 days until the
infestation has been checked. This dust mixture can be applied through the
cloth cover of the plant bed, provided the cover is dry and is not resting
on the plants.

Arsenical dust.--A dust mixture containing 1 pound of paris green
and 5 pounds of lead arsenate should be applied with a rotary type, hand-
operated duster at the rate of one-half pound per 100 square yards of plant
bed. The application should be repeated every 7 to 10 days until the in-
festation has been checked, unless the occurrence of rain necessitates more
frequent application.


Note.--Special care should be exercised to obtain a thorough, even
distribution of dust over the plants. With a reasonably tight bed, ap-
plication of the rotenone dust will be satisfactory as long as the cover re-
mains in place. Rotenone-bearing dusts give a quick kill and are therefore
valuable in the protection of youag plants. When the cover is re.r.oved
for hardening of the plants, the paris green-lead arsenate dust mixture is
recom..ended because, in addition to being toxic to the beetles, this m.a-
terial repels them.

On Newly Set Plants

Rotenone-bearing dusts.--Duxt mixtures containing 1 percent of rote-
none, prepared with cube or derris, should be applied at the rate of 3 pounds
per acre by a plunger type of duster, or at the rate of 8 pounds per acre
by a rotary type, hand-operated duster. The application should be repeated
about every 4 days until the infestation has been checked, as rotenone-bear-
ing dusts are not effective after 4 days.
Arsenical dusts.--A dust, mixture containing 1 pound of paris green
and 5 pounds of lead arsenate should be applied in the plant bed immediately
before the plants are pulled, or to the plants in the field ir.mediately
after they are set. When applied to the plant bed, the dust should be dis-
tributed by a rotary type hand-op2rated duster at the rate of 1 pound per
100 square yards of plant bed. Special care should be exercised to insure
thorough dust coverage of the stems and leaves of the plants and to prevent
excessive deposits of dust on the exposed leaves, When the application is
made immediately after the plants ore set, it should be at the rate of 2 to
3 pounds per acre if a plunger type of duster is used, or at the rate of 7
to 8 pounds per acre if a rotary type, hand-operated duster is used.

On Field Plants

Rotenone-bearinZ dIusts.--Du-t mixtures containing 1 percent of ro-
tenone, prepared with cube or derris, should be applied by a rotary type,
hand-operated duster at the rate of 8 to 10 pounds per acre, depending upon
the size of the plants. T.he application should be repeated about every 4
days until the infestation h-- been checked, and the dust should be directed
so that it will fall where the flea beetles are feeding on the plants.


Hornworais are an ever-present problem in the flue-cured tobacco areas
of Georgia, Florida, and South Carolina, and in the coastal plains areas of
North Carolina and Virginia. Wiile injury by this insect does not
major proportions during the early part of the season over much of the
Piedmont areas in North Carolina and Virginia, it is frequently of major
economic importance during the latter part of the season, particularly on
late tobacco. Injury by hornworms is very noticeable because large sections
of leaves that are located principally in the upper part of the plant are
consumed. Owing to their ravenous feeding habits, a few larvae may cause
a definite reduction in yield.



Culturalcontrol.--Fall plowing of tobacco fields will materially
reduce the overwintering populations of hornworms, and it is recommended
that emphasis be placed on this method of control.

Hand-picking.-The control of hornworms by hand-picking, as generally
practiced on small acreages, is profitable. During certain periods, however,
applications of insecticides are necessary under these conditions.

Cryolite spray mixture.-Use 6 pounds of cryolite containing at least
85 percent of sodium fluoaluminate to each 50 gallons of water. This
mixture should be applied with either a traction or power sprayer at the
rate of 60 to 70 gallons per acre for full-grown tobacco. Depending on
plant size, lighter rates may be used on immature plants. A sufficient
number of nozzles, properly spaced and arranged, is essential in obtaining
satisfactory plant coverage by the spray. Experiments have indicated that
more thorough coverage of the plant can be obtained by directing the spray
toward each side of the plant, with the angle of the nozzles varying with the
angle of the leaf. The spray should enter the plant on a plane parallel to
the leaf axis. The distance of the nozzles from the plant at the time of
spraying should be increased with the size of the plant. A nozzle should
be used for each 12 to 15 inches of plant height. Consequently the number
of nozzles used to apply the spray satisfactorily to one side of the plant
will depend upon the height of the plant. Figure 1 is a sketch showing a
suggested arrangement of nozzles for the application of spray to mature


Injury by the budworms, while of greatest importance in the south-
ern and eastern sections of the flue-cured tobacco area, is of major eco-
nomic importance over the entire flue-cured belt. Small holes made by the
larvae in the budding leaves increase in size as the leaf grows.



Poisoned bait.--A satisfactory poisoned bait for budworms can be
prepared by thoroughly mixing the following ingredients:

Corn meal 75 pounds
Lead arsenate 1 pound
(mix and apply dry)

For small quantities use:

Corn meal 1 peck
Lead arsenate 2 ounces or 6 heaping

In the application of this poisoned-bait mixture for budworm con-
trol a generous pinch (about one-half teaspoonful) of the dry mixture should
be placed in the center of the bud or tip of the plant. A satisfactory
rate of application is about 1- pounds per 1,000 plants. Under most con-
ditions control can be obtained with one or two applications. It should be
pointed out that the effectiveness of this treatment will depend upon a
thorough distribution of the lead arsenate in the corn meal and upon placing
a pinch of the mixture in the center of each plant bud.


Poisoned bait.-A satisfactory bait 'may be prepared by thoroughly
mixing the following ingredients:

Wheat bran (free of shorts) 50 pounds
Paris green 1 pound
Water to moisten 5 to 6 gallons

Caution.--In the preparation of poisoned baits for cutworms, grass-
hoppers, and green June beetle larvae, use wheat bran that is free of
shorts, as excessive amounts of shorts in the bran will, when water is
added, cause lumps to form in the mixture and make its proper application
In Plant Beds

Injury to plant beds by -utworms is likely to be serious, as ex-
tensive damage may occur within a short time. Some cutworms overwinter
in the soil as larvae, and as soon as the temperatures are favorable they
become active and feed greedily, while others overwinter as pupae, and the
adults emerge late in the winter and lay eggs in time for the larvae to
develop enough to cause serious damage early in the spring. Even though the
plant beds have been thoroughly sterilized by burning or steaming, they
should be watched carefully for cutworm damage, and at the first indica-
tions of such damage the poisoned bait should be applied evenly over the
whole bed at the rate of 4 pounds (dry weight) per 100 square yards.



-6 -

On Newly Set Plants
Cutworms may be especially destructive to newly set plants when
tobacco follows a winter cover crop, particularly when the cover crop
has been turned under immediately prior to the setting of the tobacco.
The most effective insurance against injury by cutworms to newly set plants
is to apply the poisoned bait a few days before the plants are set. The
bait should be broadcast at the rate of 15 to 20 pounds (dry weight) per
acre. Since many cutworms are active at night, the application of the bait
late in the afternoon should give the best results. Cutworms may also damage
the plants some time after they are set. Often this damage occurs only in
spots in the field, and in such cases a small quantity of bait may be scat-
tered immediately adjacent to the plant for its protection. If the infesta-
tion is general, however, the bait can be dropped near each plant as in the
case of spotted infestation. However, care should be exercised to see that
only a minimum amount of the bran carrying the poison hits the plants, as
injury may result if the bran lodges on the plant in any quantity.


Poisoned bait.--A satisfactory poisoned bait for grasshoppers can be
prepared by thoroughly mixing the following ingredients:

Wheat bran (free of shorts) 50 pounds
Paris green 2 pounds
Cheap syrup 3 quarts
Water to moisten 5 to 6 gallons

In Plant Beds

Apply the poisoned bait by hand to bare spots in the plant bed and to
a strip just inside the plant-bed walls. Apply the bait, also, in a narrow
st rip outside the plant-bed walls.

Caution.--This bait should not come in contact with the plants,
as severe burning from the action of the paris green may result.

On Newly Set Plants

If grasshoppers are abundant in a field adjacent to the one to be
set in tobacco, an application of poisoned bait should be broadcast over the
adjacent field before the plants are set. If an outbreak of grasshoppers
occurs later in the season, apply the bait to the middle of the rows only.
Scattering the bait around the edges of the field is also important. The ap-
plication should be made at the rate of 20 pounds (dry weight) per acre.


Poisoned bait.-Use the following ingredients:

Corn meal or cottonseed meal 5 pounds
Wheat bran or shorts 5 pounds
Calcium arsenate pound
Molasses 2 quarts (approximate)


Mix well and apply within 48 hours, at the rate of 3 to 4 pounds per
100 square yards of plant bed. Care should be exercised to prevent the bait
from touching the young plants. The bait should be strewn around the edges
of the bed, in pathways, and where the stand is sparse or missing. Two or
more applications may be required.


Hydrated or air-slaked lime.--When damage is confined to margins
of beds, apply the dust in a band 3 to 4 inches wide and one-half inch
thick along the margin just inside the bed walls. When damage is well
distributed over the bed, apply the lime over the entire surface with a
duster at the rate of 4 pounds per 100 square yards of plant bed. Apply the
lime when soil and plants are dry so that it will be most effective and not
injure the young plants. Late afternoon is the most suitable time for making


Poisoned bait.-To prepare a poisoned bait for green June beetle
control, use the following ingredients:

Wheat bran (free of shorts) 25 pounds
Paris green 1 pound
Water to moisten 2- to 3 gallons

Apply by hand at the rate of 10 to 12 pounds per 100 square yards of
plant bed.

Paris green.--Apply in the fall of the year on the intended plant-bed
locations at the rate of 1 pound of paris green per 100 square yards. The
bed site should be selected in the fall on land free of June beetle larvae.
These methods have not given satisfactory control in all tobacco districts,
but they are based on the best information available on the control of this


Poisoned bait.--Use the following ingredients:

Corn meal 25 pounds
Oil of mirbane nitrobenzenee) 1 ounce
Paris green 1 pound
Water 1 pint

Mix the corn meal and paris green thoroughly, then add the oil of
mirbane and water so as to give an even distribution of the liquid throughout
the corn meal. Apply the bait to rows or hills of tobacco with a stick-can
applicator at the rate of 15 pounds per acre.


Wireworm damage is greatest on newly set plants. Wireworms are
apparently attracted to the plant shortly after it has been planted in the
field. The control of these insects is a difficult problem, and as yet no
satisfactory method has been developed which can be economically used on i
tobacco lands. It has been shown, however, that large, stocky plants suffer
less damage from wireworms than do smaller plants. In areas known to be
infested with wireworms, the selection of stocky plants for planting in such
areas is to be recommended.


Information regarding the purchase of the insecticide materials
mentioned in this circular may be obtained through local dealers in agri-
cultural supplies, seedsmen, general stores, and drug stores, or through
the county agricultural agent, State agricultural experiment station, State
department of agriculture, or Bureau of Entomology and Plant Quarantine,
U. S. Department of Agriculture.

The recommendations given in this circular have resulted from a
thorough study of each particular insect and its habits. The one who at-
tempts to use them should carefully sdlct the ingredients needed, see that
they are thoroughly mixed in the correct proportions, and that a careful
and thorough application is made. Applications of dust or spray mixtures
can best be made under calm conditions and shl.ould not be attempted when
there is much wind. It is especially important to use a duster or sprayer
that will give a good distribution of the insecticidal mixtures.

Especial care should be exercised to wash the hands thoroughly
after handling, mixing, or applying poisonous insecticides, and not to
inhale excessive quantities of such dusts at any time.


Figure 1.--A suggested arrangement of nozzles for the
Application of spray to mature tobacco.

I 3I126209224 illll 6874tl Hi1
3 1262 09224 6874