Recommendations for the control of insects attacking certain vegetables, small fruits, and tobacco, and the elimination ...

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Recommendations for the control of insects attacking certain vegetables, small fruits, and tobacco, and the elimination of harmful insecticidal residues from the market product
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United States -- Bureau of Entomology and Plant Quarantine
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E-376
(Revised)


Issued April c1933
Revised March 1937


United States Department of Agriculture
Bureau of Entomology and Plant Quarantine













RECOM!..iENDATIONS FOR THE CONTROL OF INSECTS ATTACKING CERTAIN

VEGETABLES, SMALL FRUITS, AND TOBACCO











By W. H. White, Division of Truck Crop


and Garden Insect Investigations








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Contents Page

Introduction ... .. ..... ......................................................................................................... 3
Location of work.................................................................................................................. 3
Materials tested.................................................................................................................. 3
Principal insects involved.............................................................................................. 3
Recommendations for control............................................................................................ 3
Cabbage worms on cabbage.................................................................................................. 4
Materials for dusts........................................................................................................ 4
Materials for sprays...................................................................................................... 4
Relative effectiveness of dusts to specific cabbage insects........................ 5
D e r r i s .................................................................................................................................. 5
Pyrethrum .... ; ................................................................................................................. 6
Pyrethrum-derris extracts in combination.............................................................. 6
Paris green dusts............................................................................................................ 7
Cryolite (sodium fluoaluminate) dusts.................................................................... 7
Calcium arsenate dusts.................................................................................................. 7
Cabbage worms on cauliflower, broccoli, kale, and collards.............................. 7
Cutworms and corn earworms on cabbage........................................................................ 8
Cabbage webworms on cabbage............................................................................................ 8
Celery insects...................................................................................................................... 8
Celery leaf tier.............................................................................................................. 8
Celery looper ......................................................................................... ..................... 8
Cutworms... ........................................................... .......................................................... 9
Cultural practice........................................................................................................... 9
Lettuce and spinach insects............................................................................................ 9
Melon worm and pickle worm.............................................................................................. 9
Pepper weevil...................................................................................................................... 10
Vegetable weevil................................................................................................................ 10
Mexican bean beetle.......................................................................................................... 11
Sprays ............................................................................................................................... 11
D u s t s .................................................................................................................................. 1 1
Strawberry weevil.............................................................................................................. 12
Tobacco insects .................................................................................................................. 13
Tobacco hornworms.......................................................................................................... 13
Flea beetles .. ................................................................................................................. 13
Clean-up measures as an aid to control.................................................................... 14
Where to obtain insecticides........................................................................................ 14





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INTRODUCTION

This is a revision of multigraphed circular E-376. as issued by the
Bureau in '.pril I.-. The devel- w:i.,ts of the 1936 season at the various
laboratories of this Bureau have made desirable certain changes in the recom-
mendations issued last year.

LOCATION OF WORK

This 7. r:u's researches on methods of control of certain insects, having
for their o jct th. elimination of harmful insecticidal residues from the
vegetable pouts, are bei conducted at the following field laboratories:
Alhambra, "-'' Baton Roit La. Biloxi, Mims., Chadbourn, N. C. Charleston.
S. C., Columbus, Ohio, Sanford, Fla., and Phoenix, Ariz. The work on tobacco
ins--"ts is being conducted at the following locations: Clarksville, Tenn.,
Quincy, Fla., Oxford, N. C., Florence, S. C., and Windsor, Conn.

MATERIALS TESTED

The recommendations included in this circular are based principally upon
tests with the following insecticides: Dusts: Commercially prepared or home-
mixed dtrris or cube root powder, pyrethrum powder, and cryolite (natural and
synthetic), used with various diluents, paris green diluted with hydrated lime.
and commercial calcium arsenate in the undiluted form and diluted with sulphur.
Sprys: Derris or cube root powder in water, commercially prepared extracts of
derris and of pyr:.thrum and combinations of these materials, and cryolite
(natural and synthetic).

PRINCIPAL INSECTS INVOLVED

The principal pests involved in these experiments are several kinds of
lepidopterous larvae attacking cabbage and including the "nqiorted cabbage worm,
the cabba,_e looper, the diamond-back moth, the cabbage webworm, the corn ear-
worm, and cutworm,.. Also the celery leaf tier, the .'.:xican bean beetle, the
pF-=:,,r weevil, the vegetable weevil, the melon worm, the pickle worm, the
stra.-.1erry weevil, tobacco hornworms, and flea beetles.

RECOMMENDATIONS FOR CONTROL

"-..e follow. 1, g recoamei.lrtions are applicable only to certain crops on
which -rul insecticidal residues may occur on the marketed product and are
the best methods available that can be utilized and at the same time insure
agair.;-,t h-.irmful r-sidues remaining on the product consumed by man.

It will be noted that lead arsenate is not recommended for the control
of insects atla-ki.-.g any vegetable crop considered in this circular.

The use of other -Qrsc7.icals and cryolite is, however, sit.--ested as a
control for certain insects on several of the crcp_ u..-ir consideration. This
3, ..--i .. is madeI with '. L. ,. t.hat thje poison should : .. be used after
... .- .....--: -, r !7 : n- of fruit or folia-e which will be :,1y o m,:!'k I or
cor0 s T .. "''_ in '. -:~ ',.<**:. it j_ definitely known that wash njg or h', -'rr:.
iill r remove all czpra resilu1es..




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In the interests of the industries concerned, it is strongly urged that
the growers be warned of the poisonous nature of arsenicals and similar mate-
rials and that they take special precautions to be certain that such materials
do not remain on the marketed product.

From the evidence at hand, the compounds of derris, cube, and pyrethrum,
when applied at the dosages recommended herein, should not leave harmful
residues on the market product. The active principles of these materials are
rendered inert within a comparatively short time through the action of sunlight
and exposure to the air, especially when spread thinly over the plants.

CABBAGE WORMS ON CABBAGE

As a general recommendation for the control of the imported cabbage
worm, the cabbage looper, and the diamond-back moth on cabbage, the following
materials (as dusts) are recommended in the order listed, at the dosages
detailed later in this circular.

Materials for dusts

(1) Derris,
(2) Pyrethrum,
(3) Paris green, cryolite, calcium arsenate.

The dusts containing these materials should be applied in such a manner
as to cover all infested portions of the plant, care being taken to reach the
insects whenever possible. The rate of application may vary according to the
size of the plants. Applications of 15 to 20 pounds per acre, per application,
of the dust mixtures discussed later have given satisfactory results. Applica-
tions should be made in accordance with the more specific recommendations that
follow; they should begin when the worms first appear and be repeated as often
as necessary to protect the crop.

It is essential that the insecticides be applied when the worms are
small, as the larger ones, especially the cabbage looper, are usually more
difficult to kill. Furthermore, it is essential that the worms be killed
before they have caused appreciable injury to the plants.

NOTE: Paris green, cryolite, and calcium arsenate should not be used
on any portion of the cabbage plant that is to be marketed. This means that
cabbage intended for marketing as U. S. Grade No. 1 (which allows four loose
outer leaves) should not be poisoned with these materials after the headbe-
gins to form. If the marketed product is to bear a greater number of loose
outer leaves than those allowed in the above grade, these materials should
not be used after the plants have been thinned or transplanted.

Materials for sprays

In general, dusts have given better results than sprays in cabbage
worm control. If desirable to use a spray, the following materials are recom-
mended. Experiments to date have not indicated any special preference for




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either of these spray materials on the basis of their effectiven?-.-.

(1) rorris root powder in water.
(2) t-rethrum extract, or pyrethrum-derris extract combined.

Relative effectiveness of dusts to specific cabbage insects

Based ...',n the relative efficiency, at the dosages recommended herein,
of each of th insecticides tested, ,igai_,st each of the principal species of
ncal ,, worms p Aresent, e..,.riments indicate: (1) That as a control for the
iLorted ca bage worm. derris is more effective than pyrethrum, paris green,
cr olit or calcium arsenate; (2) that derris and cryolite are approximately
'qucl in effectiveness in controllirc the c,.Lbage looper, and that both mater-
ials are more effective thn;, paris green, pyrethrum, or calcium arsenate;
(3) that derris and calcium arsenate are approximately equal in effectiveness
in controll.:...-, the larvae of the diamond-back moth, while pyrethrum, cryolite,
and paris gr'.?-:, are relatively less effective for this speci'-s.

Derris

Derrrs dusts.--Derris dusts containing 0.5 to 1.0 percent of rotenone
have given very proci.-ing results in four sections of the Central, Eastern, and
Southern States. Satisfactory diluents for the derris root powder are such
nonalkaline materials as finely ground tobacco dust, finely ground inert clay,
talc, diatomaceous earth, infusorial earth, wheat flour, dusting gypsum, kaolin
(china clay), and finely ground dusting sulphur. Some of these diluents have
the advantage of being more economical in cost and more readily available in
some sections of the country than in others. Indications are that derris re-
tains its insecticidal value for a period of only approximately 1 week in the
field, under favorable weather conditions, although further work must be done
before definite conclusions can be reached upon this point. Satisfactory re-
sults were aljc obtained with commercial dusts containing approximately 0.5
percent of rotenone.

Te 'jtenone content of derris root varies, and purchases should be
made on the basis of rotenone content, total extractives, and d,_':ree of fine-
ness. For example, a dcrris root powder containing 4 percent rotenone should
contain no less "'.a., 14 percent tot'il carbon-tetrachloride or ether extrac-
tives. In general, the total extract (either by carbon tetrachloride or ether)
should aver?-7e appro;z. '*m:tely three and one-half times the rotenone content. The
derris root powder should be of such decree of fineness that not less than 90
percent of it will pass through a sieve having 200 meshes I', r linear inch, and
all of the material (100 re-rcent) should pass through a sieve having 30 m';:hes
per linear inch.

The rot;r.one content of the finished mixed dust dependv, of course,
on the quantity of diluent used as well as on the percentage of rotenone in the
or:gi.. l material. Insecticide companies now sell high-grad., finely ground
derri.'z powder of specifie-i rotenone content made by blendir.7, the various an-
alyzed batches.





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To prepare a dust containing 1 percent of rotenone, use the following
formula:

Derris powder (4 percent rotenone) 25 lbs. (1 part by weight)
Diluent 75 lbs. (3 parts by weight)

To prepare a dust containing 0.5 percent of rotenone, use the follow-
ing formula:

Derris powder (4 percent rotenone) 12- lbs. (1 part by weight)
Diluent 871 lbs. (7 parts by weight)

If the rotenone content of the derris powder is greater or less than
4 percent, the proportions of inert diluent must be varied accordingly. For
example, a derris powder containing 5 percent of rotenone should be mixed with
4 parts of the diluent by weight, that is, 20 pounds of the derris powder
containing 5 percent of rotenone and 80 pounds of the diluent, to obtain a
1-percent rotenone dust.

Derris dusts have also given an indication that they may aid in the
control of certain aphids, as well as flea beetles which infest cabbage and
related crops.

Derris sprays.--Good control has been obtained with derris root powder
(containing 4 percent of rotenone) in water at the rate of 2 to 21 pounds per
50 gallons of water, giving a rotenone content in the spray ranging from 0.02
to 0.025 percent. If the rotenone content of the derris powder is greater or
less than 4 percent, the amount of the powder used should be varied accordingly
in order to give the above indicated strengths of 0.02 to 0.025 percent rotenone
content in the spray. For example, if the derris root powder contains 5.5 per-
cent rotenone, l1 pounds of the powder should be used to give the desired con-
tent in the spray. Under some conditions it may be necessary to add a nonal-
kaline spreader or sticker to the spray, such as high-grade liquid or powdered
neutral coconut oil soap, miscible pine oil, or one of the sulphonated oils.

Pyrethrum

Pyrethrum dusts.--Pure fresh pyrethrum dust, containing approximately
0.9 percent total pyrethrins, diluted with 2 to 3 parts of the same diluents, by
weight, as recommended for use with derris dust, have shown promising results,
For the most effective results it is essential that applications of this ma-
terial should be made late in the afternoon or early in the evening.

Pyre thrum sprays.-Fairly satisfactory results have been obtained by
the use of commercial pyrethrum extracts. These extracts vary as to their
pyrethrin content. The directions given by the manufacturer should be used
as a basis for the dilution of these materials.

Pyrethrum-derris extracts in combination

Fairly satisfactory results have been obtained with commercially pre-
pared extracts of pyrethrum and derris in combination. The directions given by
the manufacturer should be used as a basis for the dilution of these materials.






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Paris green dusts

Result- indicate that paris green is more effective as a dst than as a
spray when u 1 at a dilution of 1 pound to 9 pounds of hydrat, lime, relied
at a rate of pounds per acre, per c',.plication, until the plant ---ins to
head, provid- d the headed cabl'3,e is stripp',d to four loose outer or wra..,. r
leaves when being prepared for market, If the marketed product is to bear a
greater number of loose outer leaves than those alloy, ed in the aeo.'- Lr:.d,,
paris green should not be used after the plants have been thinned or tranis-
planted.

Cryolite (sodium fluoaluminate) dusts

Both .-':.thetic and natural cryolite prepared for insecticidal pu'-j:,)7es
have given favorable ricsults when mixed with from I to 2 parts of the diluents
mentioned for derris dusts. The same car- should be exercised to avoid harmful
residues from cryolite, as has been prescribed for ars-nicals.

Calcium arsenate dusts

R .Fsi-i' wi h cc.a :-n 'ci l ca im arzc r:: -: for ,,a n.aa5.:. --_r. r-.. c.. .'.-.
sh.o','n a ,i nr : -,o.. L T -.; to :xic, ity of v'r-,'9'. s I dF:,r of + i? ...- .i .. ...
ars .ciate. i1: !,.- u:" I/L: i d or.r :, .'- '"~ fl y 't sf'ct r r, ... : 1 I :- : ; ':
at tl'.? raT.? :2 15 i.o 20 o--,.n::n r '-.. r a plratio -: tc T of
h r u r s ;e r th7is turia. .' f.i''j 7:t to I.: 1 + :F ?
mentioned for paris green and cryolite

CABB3.GE WORMS ON CAULIFLO,,'R. BROCCO LI, KALE, A1L, CCLLA-'.

T R.'...:au 1-.s :ot o e '.ad J a. Ci.:: rtLU ity to coi:'.:c c 1.. -
peric-.-.'ts o: "ha '-O'.trol of ccl'e ? ,: :;- on 7a,.l_ fl -2. '. '..' o r
7o~l ,l rds I... gen..-r 1 i T. it ".*.I -'; .... ; 'is : i The d, rri ir.A i ": .*.1 j.:;,i.".-.K i.:
shcld KI'.' ,1", sfrrlo rf sult'. ca f'es: crc,'p.: as.-- .hte anO;' ,T,'-1- 1, pUf,, o-,:i
a -ood coverage of th'- iiffcted part of0 tha'. piat can be c uta : I :!

o- c: r, y : r' 'ri t' in raei fornia hav- shcwr L'hd t'? '0". c.r ;.,
or" pyre*. ^r..'r' "''i? t r:,-:'t,.,r: :*, a" "..h- ':lil ut io:- .?" ha" ^ ,:::-. :-: *i .:ir *I ,,'.i
,coblag ?. .av' a' s ti f~ctory r._-:ul-s the co;.trcl f t;c 21".:C. -_- r',-,-.. :,-, r r ,'
sp'cier of 0 ?3 gc '.7,r cn cr z'. l .f v'.. t'".- did cr. r :-a-. It ., .:i
_.0o b eq c"-.^ i !ly iLr--c t t r:- .'.* vo "- th' tr=' ... -. 'rl.' i.. tr,,.,
'lF ,'i r- .-ipn .."' t C ,i,, f r,."'r r'h''. l + r !- s r- t nCr' "' 'nr 1 ''" _t
-l __ _. '' ,. "> i n '1 *' '.V ^ r r r + I -1 t. r .. -e ; ,- i ; 1 '' .',

,"f ne.rl" 1 r e r ',,1iflo',er rln.tt Good r-sul1ts ,,.'.. re 1-r, o'-i-3 rr] :'.>9r.
caLbaU e a .q or ri,: on cau12 f lo'.''er ".. -,,.: r ph r-d-- r rl- root it :iin rc
0 02 to 0 02- perc ,nt of roTimone v..iz. ? 3 o 2t p ounds c" r:-rr. s root :'""."-r
containing 4 percenL of rotc-none per 50 gallons of ,vater,)

Tne ?--r-rim-;i:ts of 1934 on col art-Ir s ir.dicat- that -', : :- t:r-. .- ;". -
ccmf on srDeci.e of c-'-:bage '.'orm? c',a be c:fit rot .,:d sat isf.:t r; '.' t' r. rr 0
du-t mixture cortair -ini 0.5 percc-.t of r.t :.oone Less sa 131..?,t -;- rF,' 't., '-.
obtained witi. ,yrethrum po.,der co:'.ainiir. 0.9 percent total pt'ru T:, ; : cd,





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with 5 parts of the same materials as mentioned for derris dust. It should be
emphasized that arsenicals are not recommended for cabbage worm control on these
crops, owing to the poisonous residues likely to remain on the edible portion,
and because less satisfactory results were obtained with arsenicals.

CUTWORMS AND CORN EARWORMS ON CABBAGE

In certain sections of the country, especially during the fall season,
several species of cutworms and the corn earworm are sometimes more abundant
and cause mor-. damage to the foliage of cabbage than do the usually more prev-
alent species of "green" cabbage worms. Neither derris nor pyrethrum, at the
dilutions tested, has been effective in combating cutworms or the corn earworm
on cabbage. When such cutworm infestations are expected, a standard cutworm
poisoned bait should be used before the crop is set in the field, or, in cases
where seed is planted, the treatments should be made before the plants appear
above the ground. The early treatments can be followed by later treatments,
care being exercised to prevent the bait from lodging on any portion of the
plants that are to be marketed. When the corn earworm is present in destructive
abundance on cabbage, dust applications of paris green, calcium arsenate, or
cryolite should be made, at the strengths recommended in this circular, before
the plants begin to head.

CABBAGE WEBWORMS ON CABBAGE

Results of experiments during 1936 indicate that the cabbage webworm can
be controlled by applications of dust containing 0.5 percent of rotenone, pro-
vided applications are made during the early stages in the growth of the in-
sects and of the plants. In these treatments, the cabbage plants should be
covered thoroughly with the dust.

CELERY INSECTS

Celery leaf tier

The celery leaf tier is the major pest of celery in the Florida producing
area, and also periodically becomes troublesome in the North and in California.
This pest can be controlled by careful treatments with pyrethrum dust, the dust
being mixed with an equal quantity by volume of tobacco dust. The treatment
consists of making two applications within a period of one-half hour. The ob-
ject of making the second treatment within such a period is to kill those worms
which have moved from the web as a result of the first treatment. Approximately
25 pounds of rhe mixture per acre are necessary for each application. Except
under unusual conditions in the Florida area, one treatment, that is, two appli-
cations at a Ualf-hour interval, is sufficient to protect any one given area of
celery.

Arsenicals are not satisfactory as a control for this pest.

Celery looper

Several species of loopers attack celery. In Florida these pests are
usually held in check by a bacterial disease, and observations so far would
indicate that ordinarily no artificial control measures are necessary. These






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pests suiccUMI: ni. r'acd ly to tr?:eatitincts of !-."ric thrum pow-der as recui. ::: .ded for the
celery leaf tier, and arsel!ical applications are not necessary' .

Cutworms

The use of a poisoned bait is the only practicable .:' ,- for the control
of the m.jor ty of the _.p.ies of cutworms attacking celery. The risk frcl,
pc.'.s". residue can be elim'n..ted by distributing one of the standard cutworm
b, aits between the rows, provided care is taken to keep the bait from falling
on the plants.

In the Florida celery district the southern arm,.'-,orm is usually consid-
ered as a cutworm, inasmuch as it exhibits siirlr habits in the late stages of
its develoypm.-.t. The successful control of this species, however, -1-:ii,,'ri, on
the prompt .a .lication of an arsenical at the time the eggs are hatching. Paris
green added to the regular bordeaux mi-ture and applied when the presence of the
young worms is first detected may be used, provided no applications are made on
plants which will be harvested within a period of less than 6 weeks. From 1 to
2 pounds of paris green per 100 gallons of bordeaux mixture have been used
successfully.

Cultural practice

Under Florida conditions, the cleaning up of the crop refuse during
harvest is valuable in peast control. particularly of the celery 1leaf tier

LETTUCE AND SPINACH INSECTS

There .r- sevc-ral l'a f-f ,' in icrmrs wh'-ich may attack ). t ,* ,'- rrd ,T.i, ,-
ach. and on occasion cause c, sic.- "i ae. Pyre-thrum or rr.. is rc-c':-
mernd.d as a s-,st. tute for the. arhe:. .lc ie ntri '.ol o.f t g
the same dosages as given for cabbage ;."orms.

MELON WORM1 AND PICKLE WVORM

The i.. '-icati--ions ar.,? + it T".. .a ''. and the. p l-5le ',-:1 ..c ,'" re' w Ci.-
trolled sat:' 'cTorily on -i:uash in' th.- cI ,as ?.l areas of a;:r :'s.. r f'-N' .ir l. 1 a.:
South Cn rol ....' .r.d pro',- l- y ., l ."h," r-7- ....... i P re t urn: :" 'o: t! ',ro 'c ili
usti fy th-.? ..tr'.n e invCvqd .r n'.s': *'.' with ). -0rriF Lilp-i_ r +r," 'rc cci:-
ta'..ing.. froi 1 to 1.5 percent of rci ero -e In .r:t C-.- 0f 1 J'II Y, ,Tri'c .: ..- I
nfestat i :on :' :- c- erc: -t or "c, n 0 5- t-, r r_. rc ngth rc,t::o ,r dt -t o. ,Lid .'.
.S r, f. c- : f It is appi ie:1 'a rly ?, r'i r ulariy. ','.l-cr, t,- i f,'.,tat..on -.
he-v'y ih- h'- 1 .o- -rccr,' d i, cs .o '_,u l .. .: '' T ile finely I-rc ::.l .. i' t a-r.,: :C, .
se r. is to 1:. t..e 2,oSt ,.'f-7ctz1.- '-? d'lu'?:' Or dr0. r co".'d. fr:. .:- i. t0'.: 1.,.:d7-D
and pi.ckl.- *worm con.urol on u..' .. '- ,-.t .-i ay caut, .--i i:,, LU :
foliage of t:" cro 0 Thc. 0(.'iticn, r,, r r r,: 10 Oc, 25 purc.: It ). L'.- .-o c'lu t
clay, or ial'. .o tiu derr s-.ulphur 1,::"t.'.-: '..'i] improve, i tcd rer.: i..S r_.,..l it -j.

The tr aLtm nts should i be L: t,. "',.: ti, '.'.orms fi rst :i.-: c, i*.: ...-
c.utsr of The -.uash plant, ,,h'-h: m? b,.-.. t ,' r. 3 ,,. c-!, n. or 1.0 .'.r i," ". 1 a..
a2 r.e r above- around,. an-! ccnti'urd at 7-' .- o. -i- '.,als a ] .'i' i.h'-I v. ; r- ,,
present or t.-. crop is being harvested. Tre rate of appllicat: '01, ,._ .d





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upon the size of the plants and should range from 15 to 25 pounds per acre.
Extreme care should be exercised to see that the growing tips of the plants are
well covered with the dust, as the worms feed extensively on the young leaf
buds before tunneling into the fruit, stem, and vines.

Pyreth'um powder has also proved of some value in the control of these
pests. The pyrethrum powder should be used in a mixture with clay or talc and
dusting sulphur, equal parts of the pyrethrum and the diluent being used.

Cryolite, mixed with clay and finely ground dusting sulphur in the ratio
of 1 pound of cryolite to 1 pound of clay and 2 pounds of sulphur, may be used
to advantage in early treatments. In order to avoid danger of poisonous resi-
dues on the Larket product, treatment with this material should not be made
after the fruit has begun to set.

Calcium arsenate has not proved satisfactory as a poison for the melon
worm or pickle worm.

A bellows-type duster is more satisfactory for the treatment of the
squash crop than a duster of the rotary type because of the method of planting
and the necessity of applying the material directly to the growing tips of the
plant. In th- case of crops producing extensive vines, a duster of the rotary
type may be more satisfactory.

PEPPER WEEVIL

While the pepper weevil can be controlled by treating the crop at
regular intervals with undiluted calcium arsenate, or with equal parts of cal-
cium arsenate and hydrated lime, this method is not to be recommended unless the
residue can be adequately removed by washing. Excessive applications of calcium
arsenate may result in heavy infestations of plant lice which are capable of
causing more crop loss than pepper weevil infestations. Such aphid infestations
may be controlled with nicotine dust applied alone, or mixed with the calcium
arsenate.

For conditions which obtain in California, cultural control is recom-
mended. This involves complete destruction of pepper plants after harvest, and
also the clea;:-up of nightshade plants and eggplants in the vicinity of pepper
fields, the nightshade being a favorite winter host of the pepper weevil. The
pepper fields should be plowed at least by January 1, and all nightshade plants
destroyed by the 10th of January. This gives a period between the destruction
of the winter host plants and the planting of the seed bed in excess of the time
that pepper weevils are able to live on other than their normal host plants. No
experiments have been conducted on the control of the pepper weevil in New Mex-
ico or Texas, and no recommendations are made for the control of this pest in
these two areas.

VEGETABLE WEEVIL

The vegetable weevil is a pest of vegetable crops in certain sections of
Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, and
Texas. It is also known to occur in Tennessee and South Carolina. The follow-
ing methods are recommended for its control:






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(1)Poisoned baits catterpd liitl,,y between ro'A. and on headlands as
soon as t"r first dauiage by the adults is noticed. The bait that has been
,.E'.s effective consists of 1 pound of sodium fluoride. 15 pounds of wheat bran,
8 pounds of freshly chcppoi turnips or carrots, and sufficient water to form a
a!,. Apply late in the afternoon to prevent excessive drying out of the
bait The bait should be made up several hours in advance of application.

(2) Crop rotation where possible, to avoid building up infestations
through continuous cropping with favorite host plants.

(3) The treatment of seed beds, such as tomato and cabbage, or young
field-set plants, and crop remnants after harvest, with arsenicals or fluorine
compounds is advocated. Arsenicals or fluorine compounds should not be applied
to turnips, mustard, or similar crops, the leaves of which are intended for
food.

(4) Field sanitation. All rubbish and weeds where the insect may find
shelter during inactive periods should be cleaned up.

MEXICAN BEAN BEETLE

Finely ground derris or cube root, as well as cryolite, are recommended
for the control of the Mexican bean beetle.

Sprays

Ground derris or cube having a rotenone content of 4 percent should be
used at a dosage of 1- pounds in 50 gallons of water or at a rate of l ounces
in 3 gallons. This gives a rotenone content of approximately 0.015 percent.
Derris or cube of different rotenone content may be used in the proper pro-
portion so as to make the finished spray of a content of 0.015 percent rotenone.
If the ground root contains n high-r percentage of rotenone than 4 percent,
decrease the dosage proportionately Pc-: instance, if a 5 percent rotenone-
content derris or cube po;.'der is on hand. use only four-fifths as much, namely.
approximately l- pounds to 50 gallons or 1- ounces to 3 gallons.

Extenr sive tests indicate that no spreader or -ticker is necessary with
derris or cube in water for use on beans.

Cryolite. either natural or synthetic, may be ised -it a dosage of 3
pounds inr 50 gallons of :.,.ter. or 3 ounces in 3 gallons. '.her, cryolite is used,
treatments ni.h This material should stop .'.'hen pods begin oc form.

Dusts

Gro::ers ",ho prefer to dus, or -re -not e'quipper lo spray will obtain
fairly satisfactory results with any of 1h. following lust mixtures:

Derris powder or cube po..'de, :.y : mixed ,..th one of the following
diluents or carriers and used in dust C'orm: Talc. finely ground dusting sul-
phur, inert clay, tobacco dust, kaolin (china clayj, or other inert, finely


0.






-12-


ground material. The finished dust should contain 0.5 percent of rotenone,
that is, 12 pounds of 4-percent derris or cube and 87- pounds of carrier or
diluent. Finely ground sulphur is of value against the common red spider, the
potato leafhopper on bean, powdery mildew, and the Mexican bean beetle and is
to be preferred when any of these are present in injurious numbers. It is
likely to flow too freely from many dusting machines, and care should be taken
not to apply unnecessarily heavy dosages with consequent higher costs. Twenty
to 25 pounds to the acre per application is the recommended dosage. The use of
hoods or trailers, constructed from bamboo poles and barrel hoops and covered
with muslin, 10 feet long, used one to the row behind power or traction dusters,
makes possible a considerable saving in the dosage.

Commercial rotenone-bearing dusts usually contain 0.5 percent to 0.75
percent of rotenone and are prepared to be used as dusts. These mixtures should
not be used for spraying, unless the label on the package indicates that a di-
luent has been used which will mix readily with water.

Except in semi-arid regions, plant injury often results from the use of
calcium arsenate mixtures on beans. Lead arsenate should never be used on
bean foliage because serious injury and reductions in yields often result from
its use, even when combined with bordeaux mixture.

The beans should be sprayed or dusted when adults are found in the field
or when egg masses become numerous on the underside of the leaves. One to
three, sometimes four, applications are required, depending on the abundance
of the insect. The beans must be treated on the underside of the leaves, and
care should be taken that the spraying or dusting is done thoroughly.

Cultural control.--The destruction of crop remnants after harvest is
as important as thorough spraying or dusting. Plow under all plant remnants
at least 6 inches deep.

STRAWBERRY WEEVIL

The hibernation habits of the strawberry weevil in North Carolina
are such that the destruction of the weevil by burning over its hibernating
areas is a most effective means of reducing losses from attacks of this pest.
This burning is necessary only over areas within 100 feet of the strawberry
field, as observations have shown that 97 percent of the weevils hibernate
within 100 feet of the cultivated areas. The burning should be carried on in
the winter and not in the spring, and every precaution should be taken to pre-
vent such fire from getting out of control.

When the burning method can not be applied, satisfactory control of the
strawberry weevil may be obtained by dusting with a mixture consisting of 1
pound of calcium arsenate and 5 pounds of finely ground dusting sulphur. The
first application should be made as soon as the weevil appears in the field.
The rate of application will range from 10 to 30 pounds per acre per applica-
tion, depending upon the density of the strawberry planting. Ordinarily two
applications are sufficient to protect the early fruit. All applications of
poison dusts should be discontinued at least 3 weeks prior to the ripening of





-13-


th e first berries, be..2ause, where a lor., bearing season obtains, the t]- .ln,:nt
with an arsenical poison after this period may result in haraf.rul :'Cesidues on
the ripencd berries. In prelir.mLnary tests, both derris and pyrethri.im pci'.,':r,
applied as dusts, have shown proii.ising r.:sults in controlling this insect.

TOBACCO INSECTS

Although tobacco is not a food, it would appl:,ar that arsenical or other
poisonous residues on tcb'.cc" leaves may be harmful or undesirable to the con-
sumer, and therefore v pnec .ticn should be taken to keep residues resulting
from the use of insecticides on tobacco at a minimum. For this reason, lead
arsenate is no longer recommended for use on tobacco.

Tobacco hornworms

A fairly satisfactory r,-m,:dy for tobacco hornworms consists of a mixture
of paris green 1 iart and slaked lime 6 parts. Th,.is dust should be applied with
a hand-operated crank duster for small acreages and a small traction duster for
farms gro.'.ving as much as 20 acres of tobacco, at the rate of 7 to 8 pounds per
acre, per apF.plication, the rate depending upon the size and type of tobacco.
Especial care should be observed in the manipulation of the crank duster in
order to obtain a satisfactory coverage, while at the same time k-eeping the
rate of application as low as possible. The dust gun nozzle should be held in
the center of the space between the tobacco rov,'.s and not aimed directly at the
foliage. This precaution is essential to avoid placing heavy deposits of paris
green on certain leaves, which would cause serious burning.

Tobacco grown under shade cloth in Florida and Connecticut is protected
to a large degree from hornworm attack by the cloth walls and topu. of the shade
structure. Efforts should be made to keep the cloth intact throughout the
growing season. The 1 to 6 mixture of paris green and lime may be used if
applied with care. The rate of application should be about 4 pounds of the
mixture per acre for each treatment.

Fall and winter plowing, by which process the overwintering pupae are
destroyed, is an effective cultural control for reducing the population of
hornworms in tobacco. Hand picking of the worms, where the acreage is limited,
can be practiced to advantage, especially with low-priced labor.

Flea beetles

The most satisfactory control for flea beetles attacking tobacco is a
derris or cube dust containi-,, 1 -:-.rcent of rotenone. These dusts are obtained
by diluting derris or cube ro,,'d:r to the desired strength with a clay diluent.
The follov.'ing dosages of dust are recommended for each application:

For plant beds, I pound per 100 square yards, applications to be re-
peated e.ery 4 days until control is obtained. For newly set plants,
3 to 5 pounds per acre, applications to be repeated every 4 days until
control is obtained. For the growing tobacco crop, 6 to 10 pzur.:is per
acre, depending upon the size of the plants, -pplications to be rc-peated
every 7 days until control is obtained.




UNIVERSITY OF FLORIDA

-14- 1_ IIIII Itll II11illl II 11 11111111 1 II li 11111
3 1262 08721 6589
In shade-grown tobacco when joint infestations of flea beetles and
grasshoppers appear on newly set plants, barium fluosilicate is recommended.
This material should be applied at the rate of 3 to 5 pounds per acre for each
application. The clay diluents used for dusts to be applied on tobacco some-
times leave a whitish deposit on cigar-wrapper leaves grown under shade. This
is undesirable, and sterilized tobacco dust has been found to be a satisfactory
substitute for the clay diluents for use on the shade tobaccos. If tobacco
dust is used, the manufacturer should certify that the dust has been sterilized
and that it is free of pathogenic organisms which might spread tobacco diseases.

CLEAN-UP MEASURES AS AN AID TO CONTROL

Emphasis should be placed on the thorough cleaning up of crop remnants
after harvest. It has been observed, in the southern producing areas partic-
ularly, that fields of harvested cabbage and similar crops serve as a source
of infestation to new plantings.

WHERE TO OBTAIN INSECTICIDES

Information regarding the purchase of the insecticide materials men-
tioned in this circular may be obtained usually through local dealers in agri-
cultural supplies, seedsmen, general stores, drug and department 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.




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