October 1949 F-787
United States Department of Agriculture Agricultural Research Admini strati on Bureau of Entomology and Plant quarantine
FIELD-PLOT (X.MUARIhONS OF DDT AND) OTHER
NEW MATERIALS FOR CONTROL OF CATERPILLARS ON CkBBAGE
By W. J. Reid, Jr., and F. P. Cuthbert, Jr*
Division of Truck Crop and Garden Insect Investigations l/
Several series of studies have been made for the control of caterpillars that commonly attack cabbage and related plants in the South. Arsenical and fluorine compounds.. pyrethrum, and rotenone-contairdng materials have been tested, and the results published (.2. j L ) One series of studies was begun in the fall of 1932 and continued through the spring of 1937 to test the effectiveness of pyrethrum and rotenonecontaining materials and combinations of them when applied at various intervals. Another series of toxicity studies was begun in the fall of 1941 and continued through the spring of 1948 to test materials that might be used to conserve or replace the insecticides then in general use-the arsenicals because of their extreme toxicity and the others because of their scarcity or low toxicity to certain species of insects. Particular attention was given to DDT after its high effectiveness against most of the test insects became apparent in the first trials of this material in the fall of 1943. This publication has to do with the toxicity tests made from 19141 to 1948, inclusive, and with DDT-residue studies made in 1945.
A total of 54 field-plot experiments were conducted at the Clemson College Truck Experiment Station, Charleston, S. C., on spring and fall pUntings of cabbage grown during 14 crop seasons. Each insec-ticide was used on 4 to 12 (usually 4 to 6) randomized-block replications of field plots consisting of 1 to 3 rows of plants, Two replications were made of 12.. and 15-row plots. The rows usually were 3 feet wide and 50 feet long aid bore about 45 plants, An implanted alley 3 feet wide separated the ends of plots.
One to nine applications (usually 1 to 4) of each material were made in each experiment. Duists were applied with rotary hand machines, sometimes used in conjunctioni with a cloth,-covered hood and a cloth a~pron, which reduced insecticide drift between plots as Well as gave more uniform
I/ In cooperation with the South Carolina Agricultural Experiment Station.
f I Lr I t i t&J ,5 4L; I-- ed wi t n a A: :, i a, 3-W ic !-. m- n 4 Xg. i I no
at fairly One o:- twc trl;,,s per raw werv
w tr. t -.e ulu!jter arj, orio5 trips witr-, t.-, 5,1:-ii ar, dtperullng
r, sle of the pla!A!3. -i.-: -&ntity ul' cust ai ,plied per acre at
t,_ne r&r.gO3,d -, 4 jj mall plants to J'7 ;)o ,Lrzs on lArjo
a the avpriA6ea fc r exi.-)rl-me-Am rari,;ed from 20 to
I -i ::+ray f- m :)7 t o 4.03 and averaged 90.5
a I - il, j i 11 ca t, ,
rp V r!
nc 9 P-1i I
r!bb )n --rid h =t-r m! I t
tht, nu t-e t3 n .ht- --e r ia I e -,-,I
h ri T, ri e r-.; a # a pe f e d th e r D,,, r-D ph7 I te D r V A .B ri e OIC _JB 4
jr WV _VS
tG. -a "b- ij
e fol i r-0 th -, t p.y r- ph v 1 1, 'c v-ft a F t r, i a i v" 8, ns .
1.0 impregnated dusts we. ts ,r 3part! d by c i s 6 71IT
a setting point of 89' o2 C. ) n a -, L' --it:v- n involAt' lot
5olvent, CM-qi5ttg C-f di- and t:71- tLvl azd
i n the 3olition into a f lairf ta' c in the o' dustmachine In operation,
i,,e5-alt3 are based on relAtive numbers of cat-ariAl-Lars, bY sp-eclost !3ji-vlving on comparable numbers of plants of each plot, and, I.-. acxzo ax-,,eriments in wUch the materials wers applied several tlr i, ,i <)n the
-roportions of caterpillar-
in survival counts that followed tw,- jr more inBecticicta Tese Survival and yield dat4L were otAained from plants ul-tKin Lmner
feat of each plot, end on the mi, dle row of -rorw plut5. T3tAls of 40 to C>00 plants receiving each insecticide in each ex;, brl.rkent Nere &xwLined, ,iio n,=ber usually depending upon the ai2e of the plailts iLntl tw.--a &bmdALnoe ail'i distribution of the in8acts. ka a rule) C'eta"arl 13 t -: k4 25 i,4,ants
plot were exAmined between the seconci and f ourtmontL -a., 'S af ter e&ch
ctlc de application. Grudging of plants at tar-ve.3t clase.I f ,ati on descrlba d by Reid (1). Plants classed as c& ef- 4 Ilar ciazAged
tnu:js prevented by caterpll-larn from pro"lucing Wny ar- "'hcse
f1rm hrdad- and four Owrapper" !(.).aves were a to Irade
I bo (-au5e of excessive cAt,,rp11.ar injury.
i(E-'L-) 1, 1 LTt
The t--rms *supo rior* and inferiorw appli&d to t ,v ,5 &Is
i..oA n tIAt the, differences between surviving caterpill'a -6 Were
mlTilfl .ant at odds of 19 to 1, or greater. 7he teims Infar-lor-O
an.1 "greatly super-ior" denote high sign-ifloanco (oddis of C,'A) t,-- I). In
--ieral, catprpillAr reductions of 95 percent. cnd above WiLi n' More than 1 or 2 percent of plants dwnage-d by caterpillqrs, will 0,* r*g"rdod 43 ex,- )llent control; reitictions )' -I, to 94 percent &n,-i not more t
about 5 percent of the plants damaged, as good or Bai~a control; reductions of 50 to 84 percent, and not more than 11 percent off the plants damaged, as fair control-; and lower reductions or greater numbers of plants damaged as D~oor otl. In this publication several noctuids
comprised largely of four 8jcenamely, the black cutworm (A rtie y'pollon (Rott.)), the granulate cutwormn (Feltia subterranea iTthe corn earworm (Heliothis a!MjgerP (Hbn. )), andx the fall ar~yworm (Lpym fnl~d (A. iS.T7 ill be considered as a group and referred to by
their subfamil7y namne, Agrotinae.
Barium fluoslitcate dut off approxinately7-prnttrrt
(includin-_g a c~rilmixture containing peenobalosiae
and 8 percent of cryolite) gave fair control of the- -1icage loopera Agrotinae. A 50-percent barium ffluosilIc~te, dust i ai nly fa."r kiof the cabbage, loopvr, imote abbageworm, andi diankon_-,dback moth. A.S used, barium fluosilicate proved abut- as effective as cryolite In comparable dosages.
Techinical benzene hexachloridt duste- o f 1-, ; n -pecn aa
isomner content gave good to excellent rtontrol of theipre cbaeo.
diamondback moth, and Agrotinae, but only fair to good con-1trol tof ca_,bbage looperse Dusts containing 2 and 3 percent of gam gave high reduction of oross-stripeci cabbageworms. These three dilutions were aotequal; effective against the all-spedes cAterpillar infestions except in one test where a 3-percent gem"ade a superior to a1erntdt A
0.3-percent gamma dust proe 47 t 7 percent kill Cfteixpra cabbagerorsm, diamondback k moth, and 1op~ ntwo tests,Anes il ur
gamna-isomer duet of -pretirngbproved abu-.t4xca a technical benzene hexach2.oeide duat of 1-percent gamm coten o ac of the
species present during a spring ada fall tes-t, ktcmclb ~n
hexachioridle suspension spray teddto be 01igtly oeefcieta
a dust supplyJing.r the same dosag~e of gamm~a isomrer. zinsrx
containing abot 0,03 percent of essentially pre 'b ni
chloride prover- ,tore effective than a 70-percent rui"os gi~
Benzene hexachiorido dst ol 1- Urtgmaa t aeeclent
control (90 percent or higher) of turnip knd cac e airtde on
cabbage in 1.947 and 1948, Applications of atechnic.,al Lezee hexA chloride dust (2-percent gamma) on the foliage every 7, 10, or 14I" ays (with totals of 8, 5, and 4 applications, respectively) apeibyrdcdthle populations of a root aphid, Pepiu op., on c abbage duig.h 11 of 1947. During the harvesting period the roots of 71prA fth untreated plants had light to moderate infostatoii An 7 perc&,i .fhe plants had heavy Infestations. From 24 to 30 pecn ft m~ treatedt
plants had light to moderate popu 'lti4ons of thii-phd aind 0' to 1 percent had high ones. Evidently either the insecticide uA6 absorbed t;' ti plant or a Bufftiit quantity t r-fect the phd fell crn the Soil surface and was mixed into th, ,)I ~. i p~~ L8
CaterpiLL&rs than whw
Ai5. Nc d -r." was tsr,' e"weer, tne 7- and 10-day
r e 2- a IML:-,, t -- n ',- r- s, i c 46 o d fr- m fjev*.'*I applicAtions an P t 0 C1 -'crlde dust 11-p4roont
spray Cemi""Farlf ( ntlages of the gams iscaer.
ic, r-. do --f gama content
t o -a the -T4rcent duat caused
Jk-; Iicaticpns mad*
h e tv i n it cl ,i r' :-I g t r e h fwdi n g pe rt c-,-' mused ai t b n e o d c) I-n g m c, 3 t e ex-amplop
sl-ight InJury c t O i;ercent of the 3pra causee- slie; ,t injury to percent of ra .a i n j u-ry t c 3'1 percent, azi: never injury to 7 porceat.
In azi :ther ei:perLaant t.-.- first
-f aild uz t a c n;:, P ;).s-r er t b L rrLtn g
L9 r-'- n 7 c*as &-i 5 j;n t i-n Ju-ry t Q 2 5
t -,-tlon siio;htly tnjuxea 33
a-, e &r r -xieratel. to 10
rv c eo vw', 13,igpt a,-.,pld 7, &tlons of te Cal
X -4 loride du5t of 2- Pe rc: gummL stren- n dur-'-:-, S the f all
-1 N pe rz ma
0 k,'ectioyiabie odor or t,,Am*e wa5 noted by 9 of I-)
v., T ie raw or the cooked oant a6e C'ne person, who dcoes not like
mt-ute-d that the treated sample h&d a odor.
werr ric,. othe r indication du- rw t..tla course of the studies that Lji, r'L Z tat r, P t +J X & i,',ride wil-1 trp4rt u flaLvor or odor to 04' D&J'r ev-fT) *,hough the material It4 !,&d &fter the plants begin heading.
',--y -tbl- v TI- t --me a reno;th d h m s, t
F. he d'--amdback
when 'IP71'ell 9 V"a less
4 To 7'e -hlo-
1 1 IiA Ve thtIn 4 he I I, t4A",e -)e r
C. il oriian e
--dane dL.Li t wa!i '&i rly Lox-- c to tne 'Ai % loop-or rflativeV innffeo,,tI" i-minrt -2- e b
W i-r -t d CAL bA
,e t a &nc ri e f a e t A -orc-ent dust
;(113 to eItIWT- tfie loopo-r )r the Lxpl--ted catlbagerwcru in
ex ltirimeiitm. A chlordane "pension spray azu-4 an smulsim 19PrIly 0 1,1':# 4'.cxi to excellent reductions cvf the icoper and Lnp-ortod
-4 Rz' WRrI superior to a 3-percent c- ilordane w en & Ilied
Lt !--iR4,ges of active ingr@ llent. -.ult P-titur* dAd not
.I, V : n ---M
W 't)4 1 f' th (W f' 7 h I n rd ft r-be o n c, n b bag*
A spray consisting of 4 pounds of a 20-percent 2-chlorofluorene
product to 50 gallons of water gave only slight control of the cabbage looper and no apparent reduction of the imported cabbageworm and &toncddback moth in one experiment.
In a 1945 fall experiment, a dust containing 50 percent of basic copper arsenate (with ,ulfur s the diluent) and a spray containing 10 pounds of basic copp-r arsenate to 100 gallons of water, plus a comercial spreading and sticking agent, were inferior against the cabbage looper and climbing cutworms to a spray containing 8 ounces of technical DDT to 100 gallons of vater,.
For comparison, cryolite was considered as the standard insecticide during the early part of the series of tests reported in this paper. The material was the most readily available insecticide for caterpillar control on cabbage and related crops* Previous studies by Reid et _4. (2) had shown, however, that cryolite was only partially effective against the various species of caterpillars. DDT was regarded as the standard insecticide after its greater effectiveness became apparent.
Cryolite dusts containing 50 or 70 percent of sodium fluoaluminate gave fair to good control of the cabbage looper, the diamondback moth, and the cabbage webworm when used every 7 to 10 days. The 50-percent dilution often did not provide adequate control of the imported cabbageworm and the Agrotinae. This strength did not give adequate control of a heavy infestation of the cabbage webworm during the fall of 1944. Dusts of 70 and 90 percent strengths gave satisfactory control of this infestation. No significant differences were found between cryolite dusts of 70 percent and 90 percent sodium fluoaluminate content.
When used as dusts of 50-percent sodium fluoaluminate strength, a natural cryolite of relatively low sodium fluoaluminate content proved as effective in a 1943 spring-crop experiment against the looper, imported cabbageworm, and diamondback moth as a natural cryolite of the usual initial analysis.
The addition of 1 percent, by wei#4t, of a light grade of mineral oil of the "straw" or "pale* oil type V_ significantly increased the
&I The oil was of paraffinic base and had a viscosity (Saybolt at 1000 F.) of approximately 75 seconds and an unsulfonated residue of approximately 90 percent.
,~~- IAren (. cou l~iae h oil also) tnnded to
'ra~ tecot~l fthe Wabgel-prad diamondboack Mcrtnafrd
/ y~tt in this expjerim-ent. 7theA decreased th.e dIuat.ng ui
her.(~ DI- a x t ure, wfiich was9 no too good without oil. Similar
~t o h5 Ah&crlie dt t in a !a t I Fr_ e eri aent was ofno
(h~L fut p~vc er.c.,r to --- in all rcmpari sons for &'-I-seis
t~epi~ cnrol c,1 c ryoit e L.usit o f 70per cer.t s di La fluoa luaLn atea
cc :et aslferilor to a 3rn D ,dust against the llsece
at~ep~lr poulaIoin o~ne exermet, l one oIf 10-pentsoi
flioa~uxiate rn~ent was ineirto 1D-,-1, and 1-percent Ldst
in ohdrs Crylitewai inferior to DDT in immdiate effec-t uo
~terplar, and also In lasting p rotection.
!Y ave good to exco! lf-nt oaterpillar kill, and its effect w-s
~o~leatin, than that of any other material. Againat nxmd P07ilft' -a of the mor" importAnt species of caterpillars DDT proved mor effect re thfin any mterial tested prior to 1943. Several insecticides tested lat-er pr-oved as effecti!e as DDT against one or wre species of caterp IllIa rs6. None, hoverer, vwre superior to compoarable dosages of DDT. DDT wma fouxi to be ineffective against aphids. Several. other nev insect icides, notably benzene bexachioride and~ parathion, proved highly toxic to the turnip aphid andI the cabbage apbid, a~s veil as to the caterpillars. They viii be discussed urvier their respective headings.
In the smal- -plot field experints no signi-ficant di-fferences in
the control of the all-species caterpillar populations were foundi between DDTr dusts of 2-, 3-, 5-,, and 10-percent strengths. Thesse mixtures usually reduced tho infestations of each species by approxidzatelj 90 percent or more. DL"xta Of 3- and 5-percent strengths proved superior to a l-pqret dust In half the comparisons. A 10L-percent dust was superior to a 1-percent duetY and a 2-percent dust was superior to a 0.5-percent one, in the Onl'y comparisons made of these dilutions.* A 1-percent dust provided adcequato control of the cabbage looper, imported cabbageworm, and diamondback moth In one spring experiment, and a 3-percent dust always gave adequate control of these species when applied periodically and carefully during thq mall-plot tesgts. When a 1-percent D~dust was applied with a hand dus-ter every 14 days, 8.3 percent of the plants were destroyed by the cabbage w,3bworn, Similar use of a 2 .5-percent dust gave adequate webwor control, Observations in comeraial plantings, in which large dusting
machnesthat did not concetrate the Insecticide an the plants wore useid, indicated that 3-percent dusts applied at the usual rates of. 15 t6 2-5 pounds per acre did not always give adequate control of the cabba&ge we)bwo,.r and Agrotinas on fall oabbage. This ws especially true when the plants were small and during roiny periods. Dusts of 5-peret strengh used at ordinary rates and 3-percent dusts used at 30 to 40 pons per it-re gave satisfactory control of these more resistant species of
atepilar~when properly applied. Suspansicyn sprays proved at least
as effective as dusts when applied at comparable dosages. An emulsion spray apparently gave nearly perfect control in the one spring experiment In which it was used.
When applied every 10 to 14 days, DI dusts of 3-percent and higher strengths usually provided adequate caterpillar control. Use of these materials every 21 days was not always adequate; damage sometimes occurred on the untreated new growth regardless of the strength of dust applied, particularly when the imported cabbageworm was abundant. Most of the eggs of this species are laid on the new growth near the center of the plant.
Impregnated DIT dusts of 0.5- and 1-percent strengths proved
superior to ordinary dusts of the same DDT content. Simply adding the same proportion (2 percent) of this solvent to ordinary 0.5- and 1-percent DDT dusts during the mixing process gave dusts that were as effective as the impregnated ones. An impregnated 1-percent dust and a 1-percent dust to which this solvent was added were superior to an ordinary 3-percent dust in one experiment and were not inferior to ordinary 3-, 5-, and 10-percent D)T dusts in qther experiments. The addition of 2 percent of a light mineral oil 2/ significantly increased the effectiveness of
0.5- and 1-percent DDT dusts in two of four experiments. This oil evidently was not quite so beneficial as the solvent. The dusts containing this solvent or the oil did not have such good dusting qualities as ordinary mixtures. A more absorptive diluent might have been of benefit.
Dust mixtures containing 2 percent of DDT and either 2 percent of
nicotine (either sulfate or "free" form) or 0.75 percent of rotenone proved effective against light to moderate infestations of caterpillars and turnip aphids on cabbage. Storage of these dusts for 6 months did not affect the toxicity of the DDT-rotenone mixture but tended to decrease that of the DDT-nicotine mixture.
DDT usually was not applied during the heading period of cabbage
growth, and in most of the experiments only a few applications., sometimes only one, were made. In order that adequate caterpillar populations for
the insecticide comparisons would be assured, plantings for the spring crop often were made later than in commercial practice. Nevertheless only 1.5, 2.4, 4.9, and 9 percent of the plants getting 10-, 5-, 2.5or 3-, and 1-percent DDT dusts, respectively, were ineligible to U. S. Grade No. 1 because of caterpillar damage. Usually not more than 1 or 2 percent of the plants were damaged in plots or fields where adequate control was attempted.
No plant injury from the use of DDT was observed on cabbage, collards, and broccoli at various stages of growth. An many as seven applications of a l0-percent DDT dust at an average rate of 16 pounds per acre were made on cabbage during a spring season, and as maVy as four applications at an average of 20 pounds per acre during a fall season. Four applications
fr '-percent DDT duet at an average r.e of 17. pounds per acre also vere made on abbage during a fall season. The broccoli and collards recwvnd three appl!catons of a 5-percent dust at an average doeage of ab t 1 poun e er acre. These dusting were made with hand machines that concentrated the !naecticide on the plants.
Preventive use of DDT. --Throughout the series of small-plot experinTsi adx 'n observations of commrcial plantings the use of DDT during the preheading stage of cabbage growth appreciably reduced, and somtimes eliminated, the need for caterpillar control thereafter. Resulta vere particularly good when a heavy application was made just before the plants began heading. Effects of the DDT upon the caterpillar population often were apparent for 3 weeks to a month. Fall plantings usually needed no further control meaeures. A preventive application of DDT dusts of 2to '-percent strength made on spring plantings shortly before heading began was found to be well worth while, even though the caterpillar population was not sufficiently high to require control measures when the dustIng was done. For example, the following oberrvations were made in three commercial cabbage plantings in the spring of 1946: Not more than
1 percent of plants getting one preheading application of a 2- or 2.5percent DDT dust, at a rate of 20 to 35 pounds per acre, were "damaged" (made ineligible to U. S. Grade No. 1) by caterpillars during the heading and harvesting period. No other insecticide was used. Untreated portions of these three fields had 4, 6, and 24 percent of caterpillar-damaged plants.
Diluents of DDT dusts.--Tests vere made in both spring and fall to
compare a kaolin clay, a flaky talc, pyrophyllite, and sulfur, as diluents for DDT dusts. A dust containing 10 percent of DDT in pyrophyllite was further diluted with these materials to give finished dust, containing
1 percent of DDT. No significant differences vere found among the dasta containing kaolin clay, flaky talc, or pyrophyllite. However in the spring but not in the fall experiment the kaolin dust proved superior to the aulfur dust. The dusts used In the fall experiment vere reaining p -tions of those tested in the spring.
P '> oldue studies.--The quantities of insecticidal residue that might be pr cent on cabbage at harvest after the use of DDT at various tmen dur 2 plant growth were studied during the spring and fall of 1945. ChemIcal aralysee were made by the Division of Inseoticide Investigations.
The usually marketed portion (firm head and four loose or partly loose wrapper" leave) of spring plants given one application of a 2.R-percent DT duet just before heading began (about 4 yeeks before harvet) shaoved only 0.Y2 part per dIllion of DDT when harvested. Plants given this preheading dusting and another about midvay of the beading period bore O.) p.p.m. of DT. Plants that received only the heading application shoved 0.7 p.p.m. Rainfall was 1.70 inches between the two applicat'-ns and ).48 inch between the last dusting and harvst. Residues
found during the fall experiments were somewhat higher. Fall cabbage given seven applications of a 2-percent DDTZ dust between the appearance of the first true (crinkly) leaves and the beginning of heading (about 35 days before harvest) showed no DDT residue. Cabbages dusted until 21 days before harvest bore 6.6 p.p.m. of DDT, and those dusted until 7 days before harvest bore 9 p.p.m. These applications were made with a hand-operated duster at intervals of approximately 10 days. As has been true in earlier residue studies, the greater portion of the insecticide deposit was found on the "wrapper" leaves. On the plants dusted until a week before harvest, the two outer wrapper leaves showed 59.9 p.p.m. of DDT, the two inner wrapper leaves 54.5 p.p.m., and the firm head 0.6 p.p.m. Rainfall between the first dusting (August 23) and the beginning of heading (about November 26) was 19.34 inches, that during the last 35 days before harvest was 1.84 inches, that during the last 21 days was
0.29 inch, and that during the last 7 days was only 0.05 inch.
The fall cabbage that received applications of DDT by hand dusters
apparently bore considerably larger quantities of DDT residues at harvest time than did those given comparable applications by a power duster having six nozzles. A DDT residue of 0.11 p.p.m. was found at harvest on the usually marketed portion of cabbage receiving six or seven power applications of a 2-percent dust, the last being made about 21 days before harvest.
The DDT residues found in these studies were considerably lower than those that followed similar use of arsenical insecticides in 1943, and in earlier tests by the authors reported by White (2) and by Smith et al. (_). There was sufficient DDT on the plants, however, to indicate that it would be unsafe for DDT insecticides to be applied to any portion of the plant to be marketed or used as food. In the 1943 experiment, the firm head and four wrapper leaves of cabbage that got one application of a 50-percent lead arsenate dust just before heading began and another midway of the heading period shoved 0.0283 grain of arsenic trioxide per pound (approximately 'n.p.m.) at harvest, and those given similar applications of undiluted calcium arsenate bore 0.0398 grain of arsenic trioxide per
-ound (approximately 5.7 p.p.m.). The usually marketed portion of cabbage
gl mlar applications of a cryolite dust of 50-percent sodium
flucal~iPite content showed only 0.0087 grain of fluorine per pound (approxmately 1.2 p.p.m.).
A Derris malaccensis dust stated to contain 1.13 percent of total ether extractives, with only a trace of rotenone, was about as effective in one test against the imported cabbageworm, and only slightly less effective against the looper, as a Derris elliptical dust containing the same percentage of total extractives, which included 0.5 percent of rotenone.
Four heading applications of a dust containing 50 percent of powdered domestic hellebore during the fall of 1941 did not give adequate control of the cabbage looper.
~usts containing 1 or 2 percent of methoxgaor ve fair t good r.irtions of the imported cabbagewor ar diamor back moth in one test f a~h F :lut on. A 3-percent dust reduced an imported cabbagewonm Spjlati by 87 percent. Dusts of 1-, 2-, 3-, and 5-percent methoxyclor gave only poor to fair control of the cabbage looper, nd tne
-percent dust gave only fair control of the A .rotiJnaze. The all-specles caterpillar control afforded by the 5-percent methoychlor dust was only fair. This dilution proved greatly inferior to a 5-percent L_ dust, an: the 3-per ent methoxychlor dust was inferior to a 3-percent D1 dust. The methoxychlor dusts caused no apparent plant injury.
A commercial dust of 4.7-percent fixed-nicotine content, applied four times at 8- to 14-day intervals on heading cabbage at rates of 18 to 26 pounds per acre-application, gave poor control of the cabbage looper in a 1941 fall experiment. This dust was greatly inferior to a 0.3-percent pyrethrins dust against the looper, but was as effective against the fev Imall to medium-sized Agrotinae present.
The addition of 2 percent of free nicotine to a 0.15-percent pyrethrins dust significantly increased the kill of diamondback moth larvae, but not that of the cabbage looper and the imported cabbagewors in a single-application test made in the spring of 1942. A spray consisting of one part of nicotine sulfate to 600 parts of water plus 0.5 percent of waite laundry soap, applied weekly (4 times at about 100 gallons per acreapplication), reduced the proportion of plants damaged by the diamondback moth to 7 percent, as compared to 32 percent in the untreated plots. This spray was of no apparent value against the cabbage looper and imported cabbageworm.
Weekly use of a 3-percent fixed nicotine dust (6 applications at an ave. >ge dosage of 34 pounds per acre between thinning and harvest of the plants) gave an average of 78 percent control of the diamondback noth, which was adequate for that species. This dust gave an average of 61 percent control of the imported cabbagewora, which mas not quite adequate, and gave no appreciable protection against the cabbage looper. The diamondback moth larvae and the loopers each averaged between 5 ad 6 per plant, and the imported cabbageworms between 3 and 4 per plant.
A 1-percent parathin dust gave excellent control of cabbage loopers and a 0.5-percent dust gave good control of that species and of Agrotinae in a fall experiment. Differences between these dusts and a 5-percent I: T dust were not significant. The parathion dust. also proved quite effective against turnip aphids, green peach aphids, and vegetable weevil larvae on cabbage. The parathion dusts caused no apparent plant injury.
A 20-percent phenothiasine dust an rry containing li pounds of phenothiazine to 50 gallons of water, plus a cmuerin wetting &* sticking agent, gave only fair control of Agrotinae, the cabbage web worm, and the diamondback moth and poor control of the cabbage looper and the imported cabbaseworm in two experiments. Phenothiazine, especially in sprays, caused slight injury to stain on cabbage foliage.
A 20-percent phenoxathiin dust and a spray containing 2 pounds of a 50-percent phenoxathiin concentrate to 50 gallons of water, plus a commercial spreading and sticking agent gave fair control of the diamondback moth, poor control of the cabbage looper, and no apparent reducti on of the imported cabbageworm in one test. These materials caused lght to severe injury to the leaf margins and to the margins of hole caused by caterpillar feeding.
Two applications of a 50-percent potassium fluosilicate dust, which had poor dusting qualities, followed by one of a 33-percent dust (used at higher dosage to offset the lower strength) gave fair control of the imported cabbageworm and poor control of the cabbage looper and the diamondback moth. This material was superior to a 50-percent cryolite dust against the all-species infestation, but tended to be inferior to a 50percent sodium fluosilicate dust. The potassium fluosilicate dusts caused slight to moderate injury to about 9 percent of the plants.
One application of a dust containing 50 percont of the ground sterns of Faia speciosa gave fair to good control of the diamondback moth but only poor to fair control of the cabbage looper and the imported cabbageworm. This dust was greatly superior to a 1-percent rotenone dust against the cabbage looper and diamondback moth, but greatly inferior against the imported cabbageworm. A 25-percent ryania dust, which had better dusting qualities than the 50-percent dust, was greatly superior to a 1-percent rotenone dust against the diamondback moth, as effective against the looper, but greatly inferior agAinet the imported cabbageworm. In another test, one application of a 50-percent ryania dust was as effective as a
0.9-percent rotenone dust against the looper (neither gave adequate control), but again greatly inferior against the imported cabbageworm.
Action of the ryania dusts was slightly slower but more lasting than that of the rotenone dust. Caterpillar mortality from ryania dusts was highest between the seventh and tenth days after the dusting. Caterpillar control given by the rotenone dusts was highest on the seventh day, but dropped rapidly by the tenth. No ill effect upon persons handlingthe ryania dusts or from use of the material on cabbage were noted.
it 'I a P"A
t oa ), 11 a t I on u f a ja:,-, 1 'La-ges3d c-ust gave =4 f&,-r
-_,)nArf ,l of tm -,,-:).1&t1an, tr.;t was
tt 9 o f f e c ti a is a pe -or. 4n an rl r a ou zn
o rl !1 3: I n I c 1C-P#j r,-, was irf er- tc r-e 5
.-,,ent ri teT.one one,, In a lktf4r f t y ea r
up licatio" of a t r C. C
cabbageworm, aut ;,-,or cantr ,1 of no 1UD;:,er arw *ne moth. ihe ;2,' -percwit &,.a ;--q+ *,.:i Lnf-r. Cr UK&Lln!it
_.- 3 caterp iilar population t,- L
control), ancl 'DGtn w*!re t,,) a :.9rcent cn***
I-or-cent suba-kAl.1A duqt ,ru-iod r#j.'Lj-.ive4 a -a- t t%
-A',,irP11iar8 and w&B eliminate d after *,.'J, A i-at'n .
The sabadills. dusts cauqed no ini-ar-f, but di-, cause
enable sneezing by, persons making tip appli- atlon_-q.
r a P
Frur weekly applications of I potmd of hcird, socla f!sh-011 sor-P in
'lons of water -d by followed ml I& r a p p !I c a t on a o f a s p ray c on ts4 ni n g
_v)d of this soap to 8 gallons of water, gave an average reduction sf tQ
t of all caterpillars present cn cabbage throughout ILhe fall of '.: ,2.
spra -5 gave best control of the imported cabbagerworm and cabbage
anci 85 percent, re8pectively) and only 20 percent reduction of
-A,'nra,4o webrworm when the infestation was at Its Pe&K. Excel-lent aphid
-:,e -4 ally the more concentrated
laaq provided. These soap s :r% 3, es camd -derate to severe in ury o tr.#4 ca-bbage. Tn.s injury showed
ft a ,stunting of plant &-rowth anfi a di,-,torting (-f the leaves. 7he
lanta also were more seriously ciurLi6ed by winter temperaturta,
-aiae the soap removed much of Lhe va-V bloom from the leav*s.
wpre used in two experiments dur-'n6 the spr nj of 1' ,.3.
w1nich I involved only one application, a 4-porcent ,Ti on whi t a oak a laun d ry a La p I p o und to 6 ga,1 I ons of
i :- solution of mild fiAke goap were too ropy to foru a
5,o 5prays at vater tem ,vraturos of t>00 to 700 caused
In watii .1
in ury to 49 to 15 per: ,@.-.t ;f the plAnts and killed 50 7-he -Percent solution of the c"a sod;
percent cat*rp.11imrs. jr
s 1,i*A "JI1001t tc mu .Iorate Iljury to abo,;t thet il lants anc dllod about
cont o" the cutA-i_ lluri wtion c,50 t -, 1-00 A '-percent
)n cf the raxe 8aup it & )out s1!,eA injury to
--i-ent of the pliLnta wi,_ klil*d on-ily A-10"It 45 percent of the cAterpillArs.
In tho ot.,it r 114,.) mpr4,r.,,, toit., week:.N, a,- 4 cut'. ors of a 1-percent
w"11 to cAke I A u 7 tjf%,1 or:y nIL ght i lr. Ury, but
*4s of no appreciable value in the control of caterpillars. similar use of a spray containing 0.5 percent (1 pound to 24 gallons of water) of this soap and 1 part of nicotine sulfate to 600 parts of water reduced the proportion of plants damaged by the diamondback moth to 7 percent, compared with 32 percent in the untreated plots. But this nicotine-soap spray was of no apparent value against the cabbage looper and imported cabbageworm.
In general, it seems apparent that soap sprays strong enough to
give worth-while caterpillar kill will injure cabbage plants enough to offset much, If not all, of their value. Soap sprays of 1- to 2-percent strength may be used by home gardeners at spray temperatures of 800 to 900 F. when caterpillars are abundant and better materials are not available.
S corodi te
One application during November 1943 of a micronized "run of the mine" undiluted scorodite hydrouss ferric arsenate) dust gave fair (a maximum of 63 to 65 percent) reduction of the imported cabbageworm and cabbage looper. This material was supplied by the Division of Insecticide Investigations and contained 27 percent of arsenic, calculated as As205, and 32.9 percent of iron, calculated as Fe2O3. It apparently was ground too finely to have good dusting qualities when not diluted. A 50-percent scorodite dust was slightly less effective. No significant differences were shown between the effectiveness of these two scorodite dusts and a 50-percent calcium arsenate dust. The undiluted scorodite was inferior to a 50-percent lead arsenate dust and to a 20-percent paris green dust against the cabbage looper, but as effective as undiluted calcium arsenate dust and a 10-percent paris green dust. The undiluted scorodite was inferior to all these arsenical dusts except the 50-percent calcium arsenate one in the control of the imported cabbageworm.
Scorodite should be of some value against the cabbage looper and imported cabbageworm when used in a control program.
Undiluted and 75-percent sodium fluosilicate dusts gave good to
excellent control of the cabbage looper and Agrotinae, but only poor to fair reduction of cabbage webworms. A 50-percent dust gave fair to good control of all the caterpillars. A 50-percent micronized sodium fluosilicate dust, applied seven times at 10-day intervals, gave an average of 92 percent control of the cabbage looper, cabbage webworm, imported cabbageworm, and Agrotinae on a 1943 fall planting. The undiluted dust and the 75 percent dusts that contained no conditioning agent had only fair dusting qualities, which evidently was the chief reason for their poor control of the cabbage webworm. Dusts of 50 percent strength had fair to good dusting qualities, depending upon the diluents. The addition of 12 percent of barium carbonate and 0.6 percent of tricalcium phosphate improved the dustability of 50- and 75-percent sodium fluosilicate dusts
w-r, iT lv q r r, CL:7 r t .
PA 8 14 7 f 0 7 'j
I-,,: FIT" 6 1) e e e v p MI.
0 T1 j
"L-- i u o 9 _L1 1 Ca 13 fk _' X V n 7,' an" p r cs n 7 a, i ,i e 3_ 7
d cxe by t he 5 r t r: nt, pa2 s ia _y --a 7- e, i
arul did not a f f e ct the s i z e an,-i a -rL ran -a c f Lan a fiL t a s Earl= car donate and tri eT7 e e,:! f-, e a:- '. n t c
&5 r- ta
.&nt inJury ca,,ised by :3 -'re
D,!its r-Aalnlng 3 an," 5 per(7ant of
re 1 a t F+d ana comon"r Pcnow. &q or were
vi 7 s 7h e 71 i-, a 11 u L' -11.7
ve a s 3t mL La r d 1: 1 ons c, f '-" 7' i n =,,- t p st a, &_'n3t tne cz-o--age
he i7 p teLl cabl -Agevonn, a: I-,i tne Agrk.)tlnae. A --ercent 7_1 it -xcrllent control of the cabbie e looper a.nc A r tinae In
)i.7 "all experiment and a 3-per -ent T:F ove air t-- contrc'
'-al an-, ex, allent ntlrrl of tne 17--- -,ei
9 !-In- T pe r I me r t
-hMnO4 -U DC-:,qrS
A _t gaVe goo< :Cr...rol Of CanL ,
'3 an- A, routine one s r mg anc -ne a
ray ;D-ovi Ang a -omparable iona -o -" & -tA ve I m p el
r.t red-action of t .ese mpoc In tz.e cne experico,..pared, a -pP7,,ent toxa;-te-ne -,-,-Rt wX3 superior a, a- mt the imported! d cabbagerw 7.rm at e time f t!is
1, 4 r4t of twr- ano, tended to e supmricr agaLin3t cobtai*
I ) er lat ""f! w iffipcrtant count. ,OxW 07--e cu8tm at 3- Pmd
toy-4--ity to thp --ab'+-aie ai hdd t- 117 1 tolft'_7 ty t'- the p;rem-. aphld
per,-ont -e 'I ilm! to-o te-it5 but woore 51crwer &:,Llng
Toxaphene dusts of 3- and 5-percent strengths were, in general,
about as effective as similar strengths of DDT. There were indications that toxaphene might be slightly more toxic than DDT to the fall armyworm and certain climbing cutworms and less toxic than DDT to the imported cabbageworm. In a fall experiment at the time of thinning, there were significantly fewer caterpillar-damaged plants on plots receiving a 5-percent toxaphene dust than on those given a 5-percent DDT dust.
This difference was not so apparent during later observations. A 3percent toxaphene dust was inferior to a 3-percent DDT dust against the
imported cabbageworm throughout a spring experiment at which time this species was abundant.
A commercial dust containing 25 percent of xanthone gave only poor to fair control of the cabbage looper, the diamondback moth, and the Agrotinae in the one test in which it was used. This dust showed no toxicity to the imported cabbageworm.
Field-plot tests were made of various materials that might conserve or replace arsenical, fluorine, rotenone, and pyrethrum insecticides in the control of caterpillars on cabbage and related crops. The studies were conducted at Charleston, S. C., during the 14 crop seasons from the fall of 1941 through the spring of 1948. Twenty-three materials were applied with hand-operated dusters or sprayers at 20 to 25 pounds of dust per acre-application and 90 gallons of spray.
Most of the materials differed in toxicity to the various species of caterpillars commonly attacking cabbage in the South--the cabbage looper (Trichoplusia ni (Hbn.)), the Imported cabbagevorm (Pieris ra e
(L.)), the diamondback moth (Plutella maculipennis (Curt.)), the ca bage webworm (Hellula undalie (F.)), and several species of the subfamily Agrotlnae, chiefly the corn earworm, the fall armyworm, and climbing cutworm.
DDT was the most effective against mixed infestations of caterpillars of all the materials extensively tested. DI suspension and emulsion
sprays were as effective as, and sometimes superior to, dusts applied at the same dosage, In ordinary dusts prepared from ground DDT, 3 percent
of DDT was usually sufficient when applied every 10 to 14 days, but 5 percent was sometimes required in fall plantings to control the cabbage webworm and Agrotinae. One-percent DDT dusts, however, when prepared from a DDT solution or from ground DDT plus 2 percent of a mixture of di- and tri-methyl naphthalenes were as effective as ordinary 3-percent dusts. DDT was used on cabbage, collards, and broccoli at various stages of growth without plant injury. The use of DDT during the preheading stage of cabbage growth greatly reduced and sometimes eliminated the need for caterpillar-control measures thereafter. A preventive application just before the plants began heading was found to be well worth
r---: er to
11 j k j". -A 6L
r il 7
A. Ak W I L r- ir ma t v ft ts tox P
fA c ea-h f t h,!! mr re rtm-v c a +,e
X -0 effect vnq Seffecti Ve
7 t a,- e a r: n
e la nt a
7e r-,! n* r L I as e f -ti v a a !3 i
a c 7 c L c a ; c ar t, e q,-i-4 e a s x4 a a t C, P -7,--'-- rtt'(! d 0 F- ff I -n A I-Tercant arst:--icn !j CC 1
v -,h:- w! t,'. ar a ai t the 1-lars a--;L
ff e c t I v e :I g-&In B t A a ,, -mec
aLna e &! d tu.rdp
9& L, f JUO !' jj Cia e tag,
0 C a C- Me t 1 C)X C h C e C. '17L
enate proveet e-- -a-L-y fericr 't c
M ate r-i a I n t'na t ""Pi rl, toxic to ,ne or more species cf caterpillars, IDut c'" ":j & I -iy T rov-1 de sati q fa t o ry c or, t ro 1 c f va I li n g
W'-, r P e"- r r
Jan C s a an, a r !R t str, n g j oap-r- c o n e s ray
C f tc --ercent strenTth sho"d consfder5 0
Ci y "1 *11& re bu t d d n o t A ve good i v., g qua li ti e a
S c. '-r. e 5 mc-c'erate to severe plant injury. 3corodite, LMd .!Lted kin. a was at ut as to.-xl c a 3 a pe r ce r. t c a 1 ca m
o, at t -a4 cahta6evcrm,, but nf eri cr t o thi is
_n(! Am (i arsenate &nd paria g.---en d,.:.zta ag : st
M t a -- ,lorofl,,iorene 3; i,.icq1 L, cate ciuqt t and
-Ij wrre re'ative4 ineffective.
r !a si f v raft a ,e a C 0 nil C + he e 1 t e" t 0 f I:i r 'L rL r'- U. Bur. &it. an-- Flant junA,
F P '-t cdy L. B.9 Ar!- Thcvasl W. A.
V rt" C' J05 U-4'-d to coctrcl oatbage cAter.e ou t" rleFt. A6r. Ted,. mil. 782t
(3) Smith, C. E., Reed, L. B., and Bare, C. 0.
1942. Studies on the control of cabbage caterpillars with derris
in the South. U. S. Dept. Agr. Cir. 615, 26 pp., illus.
(4) Smith, Chas. E., Reid, W. J., Jr., Harrison, P. K., and Bare, C. 0.
1937. A study of arsenical dusting of cabbage in relation to
poison residues. U. S. Dept. Agr. Cir. 411, 8 pp., illus.
(5) White, W. H.
1935. A summary of studies on arsenical substitutes for cabbage
worm control on cabbage and limitations on arsenical
treatments. Jour. Econ. Ent. 28: 607-609.
3 1262 09227 98215