|Table of Contents|
Green pod vegetables
E-521 January 1941
United States Department of Agriculture
Bureau of Entomology and Plant QZuarantine
METHYL BROMIDE FUMIGATION OF IMPORTED PERISHABLE
By Randall Latta, Division of Control Investigations
During the winter months of 193g, 1939, and 1940 large quantities
of perishable food products imported into this country were fumigated
with methyl bromide for the destruction of certain insect pests. The
results of these treatments, some of which themselves provided the
experimental data upon which recommendations for treatment were based,
are presented herewith. Commercial fumigations were performed princi-
pally at Yew York, N. Y., or Havana, Cuba, with a few at Seattle, W')sh.
Supplementary experimental tests were made at New York, Havana, San Juan,
P. R., and Washington, D. C. The following food products were treated:
Green pod vegetables, including green lima beans, string beans, and
pigeon peas (gandules); cipollini bulbs (Muscari comosum), chestnuts,
grapes, and peaches.
Tho experimental tests were all made by the writer, with the aid
and cooperation of foreign-plant quarantine inspectors, various importers,
the Seccion de Sanidad Vegetal de la Secretaria de Agricultura do Cuba,
and the Asociacion de Cosecher3s y Exportadores de Frutas y Vegetales de
Cuba. The Cuban-American Terminal Coipany of Havan, Cuba, also cooperated
in experimental studies made in a fumigating plant they erected at Havana.
Maz Kisliuk, Jr., in charge of the New York office of the Division
of Foreign Plant Qurantines, and Herman G. Frank, inspector in that
office, gave invaluable aid in the performance of the tests, as did
W. A. McCubbin, in charge of the Sttn Juan office of the some division,
and others. C. A. Reed, of Nut Investigations, Division of Fruit vnd
Vegetable Crops and Diseases, Bureau of Plant Industry, assisted in
oxamining chestnuts for quality following fumigation. The Division of
Forest Pathol6gy, Bureau of Plant Industry, provided chestnuts for
studies of the effect on quality and insect control.
GREEN POD VEGETABLES
Green pod vegetables imported into the United States during
winter months from the Wcst Indies (Cuba and Puerto Rico) have frequently
been found infested with larvae of Maruca testulalis, s bean pod borer
occurring throughout that area but not known within continentnI United
St',tes. Cub!a green pod vegetables were formerly examined in Havana by
inspectors of Sanidad Vegetal, and reexaunined by inspectors of the
Division of For.-ign Plant quarantines upon arrival at New York. This
method wqs of doubtful efficiency. Accordingly, in the 1938-39 shipping
season shipments in which ?my infestation was discovered were refused
entry. This c;?uscd losses to importers, as some infr-sted shipments were
found rach week, and also raised the question as to whether inspection
wqs 7 sufficient safoguard, since the occurrence of live larvae in some
of the shipments e-.ch week would indicated that all shipments might be
An arbitrary selection of A dosage calculated to be high enough
to cause complete mortality of all Msoruca tostulalis larv.e at dock
temperatures w,.s made on the basis of previous experience, and a test
fumigation was midc with infested shipments of green lima beans after
preliminary trials had shown this product to be uninjured by treatment.
The dosage r.te chosen was 4 pounds of methyl bromide per 1,000 cubic
feet of sp'cc, including the load, for a period of 90 minutes in a
pa.rtia- vcuun of 15 inches, sustained for the duration of the tropt-
ment.1/ The benns were m-3dc available to the Burea.u for experimental
studies by importers in an effort to salvage thr shipments. After
fumigation R number of hampers of benns wcrc reinspccted, end when no
live l.rvac were found the beans were considered free from hazard and
The stne experizontal procedure was followed for infested ship-
rvents discovered each wc7,k from December 6, 1939, to the end of the
shipping sr-'son on April 15, 1939. The mortality of larvae, as shown by
thc cxalination of shipments after fumigation, is given in table 1. All
ex-ai ,nations were made within 24 hours.
For the snke of clearness -tn' brevity, dosage rates are heroin-
'.fter abbreviat->d similarly to the following: 4 lb. for 90 nin. in a
15" vac. All 'tosages sre in pounds of meth;'l broTidr. per 1,000 cubic feet
Previous experience 'ith methyl broide fumigation hnad shown that
insects might live several days after exposure before succumbing. There-
fore, when mortality occurred within 24 hours it wa.s assumed thqt the
treatment was well over the minimum dosage needed.
Ta.ble l.--Mortality of Maruca testulalis larvae in lima bean pods resulting
from 90-minute fumig,,tions with methyl bromide at the rate of
4 pounds per 1,000 cubic feet in a 15-inch vacuum, at dock
temperatures, New York City, 1939-1939
Tpmpera- Number of Number of l-rvae
ture ha mpe rs Dead A1 ive o
Date of pods, examined Dead Alive percent
Dec. 6 51-57 4o 30 0 100'
14 41-45 43 16 0 100
21 40-45 21 1 0 100
28 50 11 3 0 100
jan. 4 4o-43 33 5 0 100
11 50 29 9 0 100
1 39 16 2 0 100
25 34-4o 37 7 0 100
In February nd March, 1939, further studies weri'made 'tI San Juan,
P. R., where an abundance of Maruca testulnlis larvae were availablq. The
results of these and the above-mentioned tests have be6n'publish6d2/ -and.
will be considered hore only briefly.
Vacuum fumigations at temperatures between L" and 50.--Low
dosrges were found to be effective under vacuum conditions, P.s a rate ss
low as O.j lb. for 90 min. in a 15" vac. gavc complete mortality, even in
the centers of packed crates (see table 2).
Atmospheric fwigations at temperatures between 756 and 0 1.-A
2-hour exposure at atmospheric pressure proved to be as affective as a
90-minute exposure in partial vacuum. A :osa;ge as low as 0.5 lb. for
2 hr. at atmospheric pressure produced complete mortality..
Vacuuy: funig.tions at temperatures below 70.--A higher dosage was
rmecssary at. the. lower temperatures. Survivals occurred after exposure to
1.5 lb. for 90 rain. in a 15" vac. at 410r but 2 lb. at 550 and 2.5 lb. at
410 gavC complete no rtality in one test -each. (Table 2.)
2/Latta, RAndall. Methyl bromide fumigation for destruction of pod
borer larvae. Jour. Econ. Fnt. 33 (1): 176-179. 1940.
Table 2.--Mortality of Marucp. tostulalis lnrvae in string beans resulting
from 90-minute fumigations with methyl bromide in s 15-inch
vacuun, Snm Juan, P. R., February 1939
(pounds per 1,000
NumIbor of l'rvcte
*Infested beans layered in the center of a loaded crate.
Later tests at Havana, Cuba, in December
results obtained at San Juan. These tcsts were
fumigation vault (2,500 cubic feet c-picity) as
1939 substpontitited the
made in an atmospheric
0.5 lb. for 2 hr. at 70-900, enpty vA.ult--31 larvae, all a.-nrd.
1.5 lb. for 2 hr. at 700, loaded hmnpors in empty vault--90 larvae,
1.5 lb. for 2 hr. at 70-800, pods in exposed position in partially
lo.-ded vnult--12 larvae, all dead.
1.5 lb. for 2 hr. at 70-00, loaded hrmpcrs in center of loaded
v, ult--4 larvae, all Thad.
1.5 lb. for 2 hr. at 70-g0, pods in exposed. position in fully
loaded viult--13 larvae, all toad.
Green lima bcans.-At New York City small lots of Cubnn linn bons
wore fumi.-ted with ncthyl bronidc without injury, as listed in t-ble 3.
These begns 4ad beon picked at least P, week previously but hned been
under good storage conditions (500 F. or loss) during the intervcnin&- tine.
The lots treated on iiovenber 30 wore held in storage .9nd shown -n
December 5 to i committee of bean importers, who were unable to 'istinguish
between fumigated and untreiteft samples.
Table 3.--Results of experimental funigations of green lima bo.-'ns at
Now York City, 193g
Date Dosnge, Duration, Vacuum, Temp., Results
poun(Is minutes inches OF.
Nov. 11 2 90 15 70 No injury.
2.5 90 15 70 Do.
3 90 15 70 Do.
4 90 15 70 Do.
2.5 120 none 70' Do.
Nov. 30 3 90 15 43 Do.
4 90 15 43 Do.
5 90 15 43 Do.
4 90 25 43 Do.
At Sa.n Juan small lots of Puerto Rican -recn limn beans (freshly
picked) were treated without injury, as shown in table 4. One-half of opch
sample was stored at room temperature, the other hMlf in en electric
Soe of the beans fuifpted Mardh 9, as listed in table 4, were
shipped to New York City; then transported to Washinton, D. C., whore they
arrived in good condition.
An aVditional series of limn beans funin'ted with 3-lb., 4-lb., and
5-lb. -osages were sacked in ti4ht paper bags soon after removal from the
vault and stored in household! electric refrigerator. After 5 f.,s they
were apparently in good condition, but upon removal from the refrigerator
they decayed rapidly. This was qssmmed to be due to failure to allow the
pods to aerate well following ftui.ation before they were placed in the
tight bags. The experiment was repeated, cheesecloth bags being used, and
no injury occurred.
At Havana, Cuba, 16 hampers of freshly picked lima beans were
fumigated, without other load, with 1.5 lb, for 2 hr, at atmospheric
pressure at 700 on December g, 1939. After firing, the beans remained
in excellent condition for 9 de'ys at precooling temperatures.
Table 4.-Results of experimental fumigations of green lima beans at
Son Juan, P. R., 1939
*Shipped to New York.
String bens.-At S;',n Juan, P. R., several tcsts were madc with
freshly picked string beans, :s given in table 5. In one series a half of
each sample was stored at room temperature, the other half in an electric
refrigerator. In these tests increasing ai ounts of injury to pods wore
caused by dosages of 3 lb. nnd above, but with 2 lb. only very slight
injury was caused in two trials, and none in two others. Two lots treated
with 2 lb. were shipped to Now York and arrived in excellent condition.
Table 5.-Results of
experimental fumigations of string beans at San
Juan, P. R., 1939
*Shipped to New York City.
D o ,
Pigeon peas.-In San Juan one test was also made with freshly
picked pigeon peas, in which one crate was fumigated on February 23 and
shipped to Now York with numerous untreated packages. A dosage of 2 lb.
for 90 miin. in a 1511 vac. was used. There was little difference between
the fumigated crate and the others when they were examined upon arrival at
FOllowing the first trial fumigation of 274 one-bushel hampers of
green lima beans on December 6, 1939, all infested shipments (a lot under
one customs entry was considered a shipment) were allowed entry following
fumigation and reinspection. This method was followed on weekly impor-
tations until January 25, 1939, aftcr which the reinspection was eliminated
since it had become apparent that the treatment was dependnable. The
shipping season, previously terminated on April 1, was oxtendod for
several weeks with the provision that all incoming pod vegetables be
Up to April 1, 1939, 7,765 hampers of green lima beans were
f-unignted, 2nd from April 5 to 19, 4,73b more were treated, a total of
12,501. During April 97 crates of pigeon peas were also fumigated in
Now York. The trade was well satisfied with the quality of both these
products following fumigation.
When the next shipping season opened on November 1, 1939, the
Bureau required the fumigation of all entries of green pod vegetables with
a dosage of 3 lb. for 90 rin. in a 151" vac. at prevailing temperatures.
The shipments of lima beans from Cuba were fumigated at New York upon
arrival during November, but it was soon realized that this would be un-
satisfactory because of (1) cost, (2) overcrowding of existing facilities,
and (3) delay in delivery for at least 2 days fter docking. As a result,
a fumigation plant was built at Havana, Cuba, with the intention of
treating all beans before shipment. The Division of Control Investiga-
tions provided plans for the plant, and the writer tested the equipment
The plant was built by the Cuban American Terminal Company for the
Asociacion de Cosecheros y Exportadores do Frutas y Vegetales de Cuba,
and all fumigations were to be certified by the Soccion do Snnidad Vegetal
de la Secrrtaria de Agricultura. It consisted of two atmospheric fumiga-
tion vaults of 2,500 cubic feet capacity, each capable of holding 936
3/'ven though oxpnrimcnts in Puerto Rico had shown that atnosphoric
fumigation w-as as efficient %s vacuum for the destruction of pod borer
larvae, the use of the latter method w-s continued in New York, since
equipment was available and the commercial procedure hed already been
established. However, for the purpose intended, atmospheric fumigation wns
preferred for use in Havana owing to the mueh lower cost of equipment.
Based on the data obtained at San Juan, a dosage rate of 1.5 lb.
for 2 hr. at prevailing temperatures was recommended for treatments at
Havana, which was calculated to be sufficiently in excess of the neces-
sary minimum to care for variations in temperatures or other factors, and
well within the range of host tolerancc.
Under routine operation these vaults provided information on
(1) prevention of sweating end (2) length of aeration period following
It had b~en foreseen that sweating would be a problem owing to the
confining of large quantities of freshly picked beans in an airtight vault.
However, it w-s soon determined that heating was prevented if the circulat-
ing blower was operating from the time loadin; start.-d, Palthough sweating
proceeded until the atmosphere w7s near or et saturation.
7requent observations of partial -.nd full lods in thr vaults showed
that temperatures equalized to the prevailing -ir temperature regardless
of whether the hampcrs were above or below that point when loaded into the
It had been anticipate d that the creation period would t-ike several
hours, and this problem was considered s. serious obstacles in perfecting a
satisfactory commercial routine. However, actual working tests proved that
a much shorter time wes satisfactory. At the end of each fumigation .n
exhaust vent was op.-ned, the door of which dropped in front of the blower
used for circulation, thus directing all of its discharged to the outside of
the vault. At the same time two intake vents at the opposite end of the
vault wern opened to admit fresh air to repl.-ce th; air-gas mixture. which
was being ejected. Thn blower in ench vault h-.d a capacity of 1,100 cubic
feet per minute. Tests w-re mAde with % halide le.k detector of partial
and full loads,, 7nd the rapidity of aeration was detrminAnd in this mMner.
Undnr prevailing tcnip-,rture conditions (700 and -above) it was determined
theft loads of 300 to 500 hnmp rs w-re cleared of all datectable concentrai-
tions of gas in 2 hours, and lo,,ds of 600 to 300 in 3 hours. The free air
in the vnults cl.'"rcd in 45 minutes or less, so it was safe for the operator
or workmen to enter, since the definite draft toward th- exhaust vent
carried away gps still disseminating from the funig-,ted hr~r pers. Tight
hFmpers (with no cracks b tweon st.vs) ofton held detectable quantity
of gas for periods longer thar indicated above, but dissemine.tion from
thcsc occasionnal co:,tniners was such that the dilution with air surrounding
them was efficient to lower th- concetration to undetecta.ble amounts.
Other test lods wro removed froA the vaults before the hampers
wtrc' free of gas but after the air surrounding showed no CctectarbL concen-
trations. In normal h.'idling bout 1 hour elepsed between unloading and
transfer to a pr-cooler, and in all cas-s this period was sufficient to
free all h-ripers of gas before entoring refrigeration. In still other
tests hwi pers still showing detectable amounts of gas wore put in a pro-
cooler where cold air was forced through at a rapid rate. The mov ing air
carried away diffusing gas so rapidly that it was not K-(tectable outside
In the tests mado at Havana, as well as in those previously made in
New York, it was found that even though !aripors contained gas concentra-
tions as high as 100 to 150 parts per million, when they werc placed in an
exposed position, the gas removal was of a rate that allowed for very
great dilution so that traces could be found only within a few inches of
the package. This applied to large quantities of material as well o.s
shall. The observations indicated, however, that quantities of fumigatod
material should not b confined in closed quarters unless adequate
vcrntilotion is *ssurod.
During the winter of 1939-40 the following quantities of imports.
green pod vegetables wore fumigfted either at Now York or Havana, as
Green lima beins - 1',770 hax.ipers of Cuban origin at New York
ll hampers of Puerto Rican origin at New
77,293 hampers of Cuban origin at Havana
Pigcon pens ----- 5,579 boxes of Puerto Ric n origin at New York
String beans 31,667 hampers of Cuban origin at Havana
1,471 boxes of Puerto Rican origin at New York
All the produ'o funigtee. at New York wns &iven a dosage of 1Ib. f or
90 min. in a 15" vac. at tempraturcs mostly betw(eEn )400 -nd 500. All
produce fumigted at Havne was 4iven r. dlosage of 1.5 lb. for 2 hr. v.t
atmospheric pressure at prevailing temperatures (706 to 90).4 The large
quantity of string benns imported ws due to a high market following
freezing weather in bean-growing areas of the southern states early in
All three of these products were kept under constant observation,
and no injury or other lessening of quality was found. The writer tested
many samples for taste and found no difference from untreated samples.
The trade accepted these vegetables, tnd there hive been no complaints of
injury from then.
W/See footnote 3.
- 10 -
Dormant bulbs of' Muscari corosu:n, known in the tra-de by the name
cipollini (meaning "little onion" in Italian), have been imported in
quantity from Morocco for consumption as food. These bulbs wi'rt not
cultivated, but were collected from mountainsides where they grow wild
in great numbers. They were often infested with larvae of Exosona
lusitvnica, a chrysomelid beetle not known to occur in the United Stites.
Infestation was generally very light in bulbs imported during the ep.rly
winter months, as they had been in storage for some time and evidently
the larvae present had left to pupate. Soon after the beginning of a now
y~ar, however, so-called new-crop bulbs which had r:qently been dug bngan
to arrive. These were usually moderately infested. /
Until 1939 all infested shipments had bern admitted only after a
prescribed hot-weter treatment of 3 hours at ll4c F. Since pr-ctically
all importations were made during the winter months, this treatment wIs
unpopular for reasons of (1) extreme difficulty of drying quantities of
bulbs under winter conditions in unhe?.ted warehouses, (2) cost due to
excessive handling necessary in drying, and (3) high loss of bulbs in
storage when cold weather prevented proper drying. The hot-water treat-
ment wa.s efficient as far as control of insect larvae was concerned,
but owing to the reluctance of importers to use this method and the
losses following its use, the Division of Foreign Plant Q;uarantines
desired a lcss costly an%. mor satisfactory treatment.
On Novcmbrr 2,5, 1938, the first tests were made with a fow
infested bulbs rcmov ud from an importation of cipollini. Four of seven
larvae survived a fumAigation with 2 lb. for 90 min. in a 15" v-ac. at 700,
Pnd 4 of 5 larvae showed activity .fter 4 dkays following a fumigation
with the dosage raise I to 2.5 lb. Larvae of the narcissus bulb fly
(Mero.on egivstris) present in the bulbs also survived these dosages.
Because of the scarcity of available larvae of Exosoma lusitanica,
no further tests coulft bc mrtde at thnft tine, so a dos.ge rate of 4 lb.
for 2 hr. in a 15" vac. a t 650 or above was arbitrarily selected for use
in a t( st f'.i3-gation of 700 c-ses (25 to 30 tons). These bulbs woro
supplied by an ir.portcr desirous of using methods other than hot-wpoter
trKatixnt, -n(.. we-re troatcd on Deccmber 5. The bulbs were warned to
5-/Kisliuk, 1A. Some Scientific Contributions Made at the Port of
New York. Jour. con. Ent. 33 (2): 376, 1940.
- 11 -
approximately 750 before fumigation. Twenty-seven larvae of E. lusita.nica
and 17 of M-rodon equestris were recovered from cases selected at random
from the load, 9.nd all were dead within 48 hours, with bodies collapsed
and partially or wholly discolored.
Only incidental recoveries of occasional dead larvae were made
from many additional commercial fwizgations at the n.bove dosage rate
until January 11, 19)40, when a number of larvae were recovered from
beneath stacked cases of fumigated bulbs. These larvae were active when
collected but all died within a few dayrs. A later recovery of over 50
larvae in a sii.ilar manner also resulted in complete mortality.
On January 13, 1940, about 10 active larva3 were fumigated with
4 lb. for 4 hr. in a 15" vac. at 46-500. All were killed.
At Nc'w York City small lots of imported cipollini bulbs were
subjected to a series of fumigations with methyl bromide in November
1939. About 400 bulbs were used in each sample, as listed in table 6.
These bulbs were kept under observation for 30 days or longer and showed
no evidence of injury from treatment. Twenty-four bulbs from each of the
first four treatments given in table 6 were planted in the laboratory
greenhouse and forced during January Pnd February. All lots grew and
It w-As assuned from thcse tests that the bulbs were very tolerant
to mcthyl bromide ftLunig.tion, and it was on this assumption that a
treatment of 4 lb. for 2 hr. in 9 151" vac. at 650 or above was selected
for commercial use.
Table 6.--Results of experimental friuig.itions of cipollini bulbs at
New York City, 1939
Date Dosge, Duration, Vacuum, Temp., Results
po' ads minutes inches OF.
Nov. 25 2 90 15 70 No injury.
2.5 9o 15 70 Do.
3 9o 15 70 Do.
4 90 15 70 Do.
2.5 120 none 70 Do.
Nov. 30 3 90 15 143 Do.
4 90 15 43 Do.
5 90 15 143 Do.
4 90 25 43 Do.
- 12 -
In 1;ovenbsr 1339 further p~rincnt~l tests of bulb tolerance were
-ade at Washin tn, D. C., in 'I: a-ttc-pt to :stpablish the raximr. endos ges
thn't could be us sfely. Thf exerLn-ntS tested increases of -os-ge,
urtion, ntc vacu',. The results of those tests are given in table 7.
>ble 7.--Rcsults of expcrimental f:-igr' tions of cipollini bulbs .t
Wshinetorn, D. C., Novc-mber 24 mnm2 25, 1939
Treatment Decayed. bulbs
NYLber it ional
? m f-ound; nimbe c We~k
os c ~Dratioin, V 2cuum, _O r ,
ou~n~s nurs inches after 27 ter hi
'ys s -cys
4 4 15 70 0 0
5 2 15 70 1 1
S 2 15 70 0 0
g 2 15 70 11/34* 4/23* 4/10 buds x.ad
D4 15 45-50 2 0
6 4 15 50-55 2 0 6/10 buds e-Ac
4 2 15 90 0 0
L 2 25 70 6/1 0
3 25 70 3/70 0
4 4 25 70 21/1,6 3/25 4/22 bus ?ead
0 0 0
*First nu.bcr ?enotrs nuber of c'ec- yel. bulbs out of totil given
by second number, i.e., 11/34 = 11 ec-caye d bulbs out of a total of 34.
In the ex .nation of the bulbs used in this series, all tecnye!
ones w~rc r!:.ve! at ths timc-, so that the nunter of necaycd bulbs after
Ll -ays in stor-. w.re in -d"ition to the nber -fter 27 Thys. It w-.s
o sErvei th-at the checks n :any of the treated bulbs showed consil'ers.ble
evelooncnt of n;w ':u".s in the neck region. In the severest treatments c
thr oCu r bs ecr killed. ean discolored, -.nd the revmainder
worc still ir-ctivc. In direct Sssociation with this factor w-is a. signif-
icant loss of bulbs from int;-rnal dc. Therefore, whr.re both carzyitions
;ccurred- it wc.s judd t'ht treatment was responsible for injury.-/ Whore
sone i -f >ul-s wos notr. tut the remainder hAd well-cdeveloped new >u,.s,
S cay w!s consi'-re -s originatini frm ext-rnal bruises or cuts.
6/ In suseaunt studies with new-crop bulbs it -ee~ne evident that
injury to the bu coulA not be use4 .s P- criterion of fir'ig tion effect
because of the extremely snall size of the but, since it w!-s only in the
fo rnntive state.
- 13 -
On this basis, then, two treatments were considered to hvp caused
definite injury, namely, 9 lb. for 2 hr. in .y 15" vac. at 70 n 4 l1,
for 4 hr. in a 25" v!'c. -t 700, while thir2, 6 ln. for 4 hr. in a 15"
vac. at 50-55o, was on the borderline in that buds were killed but no loss
of bulbs followed. The rnmpiining dosages were apparently all within the
tolerance rqn.e of cipollini bulbs. This suggested Pa very safe marLin
between the recomriendedt treatment and the mvximum tolerance of the bulbs.
It must be pointed out th-t the above tests were ma e with "Gln(-
crop" bulbs, dug during the spring -,nd sumner nA wrll cure1 before
shipping. Thcse bulbs were probably in their n-'tural ormnt pnrio3 ot
this time, as evidenced by the presence of ncew flower uOs in the bulbs.
New-crop bulbs, which were apparently du,: durin- the 7rowin- season, 2ro
in an PTbnor.al condition and might exhibit a different rePree of tolerance
to fiuiLation treatments. Under routine commercial conditions, as will -e
shown in the following section, there was less loss from new-crop 'uls
than from old-crop fumigpted with the rccornended 3osa-e.
Various importers of cipollini >ulbs were anxious for qn -1trrnative
treatment to the recommended hot-water ir~ersioni, so after the first series
of experimental toler-nce tests in November 1935 q lot of 700 cases wls
offered by an importer for an experimental large-scale treatment. As
noted previously, ao dosa.e rate of 41 l. for 2 hr. in a 15"1 vac. at 650 or
above was selected for trial. The bulbs wcre rais K from a stora--e temper-
ature of approximately 450 to 750 by placin+ the entire lot in th-
funigating vault nf applyin; heat thrDuuh the medium of a steam coil in
the bottom. This vault was a lonL cylinder of the type frequently used for
vacuum fuigation. There was no circulation other than convection currents,
and the temperature at the extreme top reached about 1100. The endt doors
were kept open to prevent sweating. In this instance the hulls remained
in this warm location for 3 '-Ys over a wee kcr.
Following fumigation, th- bulbs were reex-miined, --ndc when all
larvae wereD found 'eaet the shipment was released from quarantine.
Samples of bulbs saved from c-ses selected at ra.do2 fror, this fun.i,;ation
were kept under observation for several weeks an,. showc. no apparent
effect from the trcatnent. As soon n-s the trade was satisfied that no
injury occurred, all subsequent inf. sted importations were fmit
rather than treated in hot water. In the fiscal ycer 1935-39, 9,925 ccses
- 14 -
During 1939, 1939, and January 19-O the recommended treatment
required a bulb temperature of 65' or above. Practically all shipments,
with the exception of two or three f'uiL'ted in the late spring of 1939,
were heated as described above to meet this requirement. In most
instances, if a sniwient of bulbs was placed in the vault late in the
afternoon, it would be warmed to 65, the followin- morning without the
air temperature at the top of the vault going above 1100. This procedure
wqs considered a benefit b y most importers because of the drying of moist
or moldy bulbs.
On Ja,.nuary 24, 19140, the recorr-ended treatment was broadened to
P1low fiuni-Rtion at storage temperatures as follows:
4 lb. for 2 hr. in a 1'" vac. at temperatures Pbove 650, or
1i lb. for 4 hr. in a 13" vqc. at temperatures below 65g.
In the fell of 1939 certain importers suggested that fumigated
bulbs did not store so well as untreated ones, although apparently there
was no effect on quality. Therefore 8n intensive study of all shipments
fumigated during the winter of 1939-40 was undertaken. Samples of treated
and untrE'atcd bulbs were saved from each commercial fumigation and kept
under observation at Washington, D. C., A nd, whennever possible, observa-
tions were made of lots in storage in New York City.
FrDm iFovember 1, 1939, until May 1, 1940, samples from 34 fumigated
lots, representing 13,111 cases of bulbs, were kept under observation for
approximately 1 month following fumigation. Each sample weighed about
4 pounds and contained from 40 to 65 or more bulbs, depending on their
size. Nine of the 3 sr imles showed considcrblb loss during storage
(sce table 9), the r-maining 25 samples keeping in oxcellont condition.
Whrr. two or three bulbs in a sample decayed, it w-ts attributed to normal
storage loss, since a similar loss occurred in some untreated samples. Of
the 9 sarplcs showing a high pe rccntagc of loss in storage, 1 was found to
have much higher loss in the sample than in a part of the original ship-
merit still in storp ge, and 2 more were from shipments frozen before
treatment. Three of the remaining 6 lots belonged to one importer who
received much cipollini from miscellant ous sources, and none of it was
selected or graded.
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Table 8.--Results of storage tests with semples from shipments of
cipollini bulbs fumigted, 1933-40
Number of decayed
bulbs in samples
Untreated. RuligatE d
60 cases in storage showed
only 0 to 10% decay.
Apr. 24 1, 302**,
Lot frozen on dock.
New-crop bulbs, arrived
wet and moldy.
0 0 Do.
0 0 Do.
0 0 Do.
0 0 Do.
0 0 Do.
o 35/49 Do.
0 0 Do.
0 0 Do.
denotes number of decayed bulbs out of total given
by second figure.
"Treated without heating with 4 lb. for 4 hr. at 490, 450, 560,
and 59', respectively.
A part of the stock treated on December 1 (520 cases), which
showed a loss of 65 out .f 90 bulbs in the sample, was located in storage
and examined January 10. Sixty cases r;'mained, stacked 5 high and 12
long in i single row. One stack wns removed from nenr the center, and
samples were taken from each cpse. The percentage of decryed bulbs
varied from 0 to over 10 in the 5 cases. New buds in a number of bulbs
cut open were in normal condition. Either the sample kept for observation
had bepn selected from a case having a large -%mount of incipient decay, or
else its storage conditions were unfavorable. The results of the exa rina-
Top case-- 2 of 200 bulbs from two locations in case decayed (1%)
Second case-- 5 of 200 bulbs from one end of c se decayed
Third case-- 12 of 112 bulbs from one end of case decayed (1O.7%)
Fourth cpse-- 2 of 200 bulbs from one cnd of case decayed (1%)
Bottom case- 0 of 200 bulbs from two locations in case decayed (0%)
In one shipment which had been frozen before treatment the loss wAs
attributed definitely to that fact, since both treated qnd untreated, samples
decayed. In the other instance of bulbs frozen prior to treatment there
wns lost total loss in the treated sample but none in the check. This
may have been due to the effect of heating the frozen bulbs.
The sa .plos from shipments fiuigated during "Tov'2bpr and December
were sel.cted at random before and after fumigation, whereas samples from
those treated after January 1 were taken from the same case in each
instance. The former method may havG contributed to a chance selection of
a sample front, ? cise with high incipient infection.
It w-is indicated th at old-stock bulbs may hve been more susceptible
to stor-l-e losses, since 3 of the 9 sarples showing loss were from that
Therefore, with unexplained high storage losses in only 6 of 314
tests, it wfs assu:md that fumigation with the recommended dosages did
not cause injury to the bulbs or fost- r conditions contributing to
I:iported chestnuts often have been infested with larvae of weevils
(Curculio sp., formerly B.laninus) a d with larvae of the European codling
moth (Lrspeyresia splendana), necessitating a disinfestation treatment.
For several years infested nuts had been trpnted in hot water of 1120 F.
for 45 minutes. This tre!tnent w.s expensive because of the excessive
handling n cessary when quantities of nuts were treated, rnd it offered the
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same difficulties of drying during winter months as wpro encountered in
hot-water treatment of cipollini bulbs. A liss exp:nsivw; and morc rapid
treatment, such as furig- tion would provide, wis de sired for use on the
Pacific coast for importations of Japrnneso chestnuts as well os in ,T-w
York for an anticipated increase of shipments from Meditcrranfan countries.
No live specimens of either species of insects likc-ly to be in
imported chestnuts were available for use in experimental tests, so
studies were made with larvae of the native chestnut weevils Curculio
proboscideus and C. aurier. The following recommendation for treatment
of imported chestnuts was based on these experiments:
Above 700--4 lb. for 2 hr. in a high sustained vacuum (2511 or more)
Between 500 a nd 700--4 lb. for 4 hr. in a high sustained vocuun
Below 500--4 lb. for 5 hr. in a high sustained vacuum
In chestnuts examined following treatments of commercial shipments
fumig-ted with the nbove schedule it w-s found thi.t all Laspeyresia
splendana larvae were destroyed.
Brief tests to determine the effect, if any on the quality of
chestnuts were made in 193g at Washington, D. C. On November 22, chest-
nuts purchased on the open market were divided into lots of 12 nuts each
and fiumigated with dos-ages of 2.5, 3, 3.5, -tnl 4 lb., all for 90 min. in
a 15" v!c. at approximately 700. The chestnuts wr-re xamiined by
C. A. Reed, of I[ut Investigations, Bureau of Plant Industry, "nd no change
in taste or quality could be detected.
On December 15, further tests were made with Ttalian chestnuts
(Castanea sativa). Dosages of 3, 4, 9nd 5 lb., all for 2 hr. in a 15" wvc.
-at 750, and 3 lb. for 2 hr. in a 25" vac. at 750 wore used. These chest-
nuts were also ex-neined by Mr. Reed, and no effect to taste or quality
could be detected.
During 1939 more extensive tests were made at Washington with
American-grown chestnuts of Castamea mollissima (Chinese), C. crenata
(Jaopanese), and various hybrids of each. 7arly- and late-maturing strains
of each were tested, as well :s immature (nuts just dropped) and mature
(nuts held about 2 weeks until sweet) samples of ench. In all, 31 samzples
were treated. Dosages up to the following limits were tested:
4 lb. for 3 hr. in a 15" vac. at 700
7 lb. for 90 min. in A 15" vac. at 700
6 lb. for 2 hr. in a 27" vac. at 700
4 lb. for 3 hr. in a 27" vac. at 600
5 lb. for 3 hr. at atmospheric pressure at 700
All the samples were examined by Mr. Reed for taste and quality,
and no change could be detected.
Importers of chestnuts showed no reluctance in accepting methyl
bromide fumigation in lieu of hot-water treatment. Starting with a ship-
ment of l1 kegs on Novciber 1, 1939, 9,316 containers (baskets, boxes,
and kegs), mostly of Portugese origin, were fumigated during November,
December, and January, at New York City, and 940 containers of Japanese
chestnuts at Seattle, Wash.
Some of the shipments of chestnuts w rc heated before fumigation
in order to t okc advantage of the shorter exposure period, and others
were fumigated at storage temperatures between 400 and 600.
Samples saved from 13 fumigated shipments wpr6 kept under obs-rvsA-
tion at Wnshington, D. C. In no instpncr! w-'s there any increase in loss
during storage, nor w ,s there 9ny effect oil t'st? or quality.
Two shipments consisting of sevcr-'l hundred ba.skets, which hud been
fumiignted on Dccember 22, were exnmincd in storage on Jnuiry 10 qni were
in almost the sam- condition -'s at the time of arrival.
A shipment of Elberta peaches from Chil; was found infested with
live adults of Pantomorus sp., a close relative of the white-fringed
beetle. An cmergency, treatment was needed for this shipment.
Comm rcial Application
Bccause pnachs hnd been successfully fumig.tcd with methyl bromide
in pr-.vious tests, the importer offered the shipment for experimental
treatment without pr limin:ry tri.-ls in this instance., The entire lot of
606 box77s w'.s fumigatcd with 3 lb. for 30 min. in 15" v-c. nt 3g-40o on
February 17, 1940. The fruit wps green. The adults of the white-fringed
beetle are known to be killed at normal temperatures with very low dosages
of methyl bromide, therefore for this closely related species the selected
ratF ws considered to be well in excess of the a.avount needed after the
cffct of a low trinporature and the use of v-cuun had been calculated.
Snriple,; of untr- itcd and fumigated peaches wore retained and
observed for s-voral days to study wiy effect that might result from
fumiigontion. Both s1npl ,s ripened normally And showed no eff-ct on cithcr
tistc or ou-olity. Later re ports wer thpt th- peoches moved through
commercial ch' nnnls without Rny r-port of injury.
A shipment of five varieties of grapes arriving in I~Nw York from
Argentina were found infested with live adults of Pantomorus sp. An
emergency treatment was needed for this shipment.
The infested shipment was allowed to move from the piers to a
bonded cold-storage plant. On March 7 several boxes of grapes of thc
varieties Thompson Seedless, Pizzutello, Black Olivet, and Ribier, all of
the so-called soft type, were removed and subjected to cxperimvntal
fumigations at the storage plant. The following tests were mede, all at
3 lb. for 2 hr. at 500
4 lb. for 2 hr. at 500
5 lb. for 2 hr. -,t 500
Each sample w-is divided, one hlf going back into storage at 340,
the other half being plxnced in an open storeroom .t 60-70. On March 11
all samples were observed by a committee of grape importers and experts,
who could not distinguish between untreated and fumigated sapls in either
those kept Pt room temperature or those kept in storage.
On March 12, 2,432 boxes of grapes were removed from storage and
fumigated with Josv\ge of 3 lb. for 2 hr. -t atmospheric pressure at
500. (The duration wts extended to 2 hr. to compensate for the increase
in pressure to normal atmospheric instead of partial vacuum as used in the
treatment of peaches.) The grape temperature rose from 340 to approxi-
mately 500 during transit to the fumigating plant. The treatment was
performed in a vacuum vault but no vacuum was used at any point in the
procedure. The grapes were removed from the plant after a sufficient
airing period and taken directly to a fruit auction, where they were sold.
L.ter reports were that no bad. effects resulted from the fumigation, but
thaot the quality was somewhat lowered by the changes in temperatures and
subs-quent condensation of moisture on the fruit.
Several types of imported perishable food products h1.tve been
successfully fumigated with methyl bromide during the past 2 y:ars to free
them of certain insect pests. Data of experiments for destruction of
these insects, tolerance of hosts, !ind commercial application !re given.
UNIVERSITY OF FLORIDA
- IIIIIIIIlMIIflIII IIIIIIIIiiiiIiIilI
In tests made in Puerto Rico, larlae of Marucs testulalis were all
killed by dosages of 0.5 lb. of me.thyl bronide per 1,000 cubic feet of
space under either vicuu fumigation conditions for 90 minutes or
atmospheric conditions for 2 hours. Green lima beans were found to be
uninjured by dosnges as high !s 5 pounds at 700 or ebove!. String beans
and pigeon peas tolerated dosages of 2 poun.'s.
Fumigation of green pod vegetables was applied connercially under
high-tomperature conditions in Havana, Cuba, and under low-temperature
conditions at Now York City, with dosage rates of 1.5 lb. for 2 hours at
atmospheric pressure, and 3 lb. for 90 min. in a 15" vac., respectively.
In 1938-39, 12,501 hanpers of green lina beans and 97 boxes of pigeon
peas were fumigated, and in 1939-40, 92,181 haupers of lima beans, 5,579
boxes of pigeon peas, and 33,138 harmpers of string beans.
Larvae of Mxoson. lusitanicn, infesting cipollini bulbs were found
to be killed by a dosage of 14 lb. per 1,000 cubic feet for 2 hours above
650 or for 4 hours below 650. Cipollini bulbs proved to be very tolerant
to me-ethyl bromide fT=igntion. FUmigaotion of cipollini bulbs wfs applied
co7,ercially, and in routine funigptions 9,925 cases were treated in
1939-39 nnd 23,-70 cases in 1939-40.
Chestnuts were ",lso found (in experimental tests) to be very
tolerant of methyl bromide fumigation as fPir as taste and quality were
concerned. In the co.Lnercial application of this fumigation, 9,256
packages of chestnuts were funigpted in 1939-40.
One co=nerci2.l fumigation each of Chilean peaches and Argentine
grapes w3s performed without injury to the fruits.