Report on cooperative experiments conducted by the Bureau of Entomology and Plant Quarantine and the California State De...

MISSING IMAGE

Material Information

Title:
Report on cooperative experiments conducted by the Bureau of Entomology and Plant Quarantine and the California State Department of Agriculture relative to the fumigation of fruit and nursery-stock hosts of the oriental fruit moth
Portion of title:
Fumigation of fruit and nursery-stock hosts of the oriental fruit moth
Physical Description:
42, 4 p. : ill. ; 27 cm.
Language:
English
Creator:
Johnson, A. C ( Alpha Cornelius ), b. 1889
Bowen, C. H
Phillips, G. L
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
United States Department of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Oriental fruit moth -- Control   ( lcsh )
Fumigation   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references.
Additional Physical Form:
Also available in electronic format.
Statement of Responsibility:
by A.C. Johnson, C.H. Bowen, and G.L. Phillips.
General Note:
Caption title.
General Note:
"E-711."
General Note:
"January 1947."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030292877
oclc - 780081274
System ID:
AA00026080:00001

Full Text
LIER ARY
FATE PLANT BOARD
January 1947 E-731




United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine

REPORT ON COOPERATIVE EXPERIMENTS CONDUCTED BY
THE BUREAU 0f ENTOMOLOGY AND PLANT QUARANTINE AND
THE CALIFORNIA STATE DEPARTMENT OF AGRICULTURE
RNATIV3 TO THE FUMIGATION 0 FRUIT AID URSERT-STOCK HOSTS
OF THE ORIENTAL FRUIT MOTH I/ Z/

By A. C. Johnson, C. H. Bowen, and G. L. Phillips,
Division of Control Investigations

The secretary of the Western Plant Board, in letters dated
December 11, 1942, and January 12, 1943, transmitted a request from
the Board to the Bureau of Entomology and Plant Quarantine for stud-
ies to be undertaken on the development of treatments for host fruits
originating in areas quarantined by Western States because of the
oriental fruit moth, (Grapholitha molest (Busck)). The answer from
the Bureau, dated January 23, 1943, pointed out that such studies
were already under way on a limited scale in the Division of Control
Investigations, but only on fumigation schedules for summer-maturing
fruits intended for immediate consumption. It was stated that funds
were not available to undertake studies of fall-maturing fruits in-
tended for storage.

In February 1943, the late D. B. Mackie, of the California State
Department of Agriculture, proposed that a cooperative project be
undertaken on this problem, ahd it was finally arranged that the
State of California would allot to the Bureau a sum not to exceed
$8,000, to be available during the fiscal biennium of 1944 and 1945,
to aid in carrying out studies along the line proposed in the orig-
inal request by the Western Plant Board. Later,at the request of
the California State Department of Agriculture, studies were also
made with hibernating larvae in an effort to reduce the dosage sched-
ules and the temperature requirements in effect for the treatment of
nursery-stock hosts.



I/This report was submitted to the member States of the Western
Plant Board, November 15, 1945, and is now reproduced in substantially
the original form for the information of others interested in this
subject.

i/These investigations were under the immediate supervision of
Randall Latta.



]AN 2 7 1947






-2-


The cooperative agreement with California terminated June 30, 1945,
This report is a presentation of the studies made during the period
covered by the agreement.

OBJECTIVES

The objectives of the study were threefold:

(1) To develop fumigation dosage schedules for the treatment of
fresh-fruit hosts of the oriental fruit moth.

(2) To study further the dosage schedules needed for the destruc-
tion of hibernating larvae on nursery-stock hosts, in an effort to de-
velop fumigation schedules at temperature levels below 60F. and to re-
duce the schedules now authorized at 60 and 70.

(3) To study the tolerance of host fruits to fumigation schedules
that are effective against this insect.

METHODS

All the tests were conducted at St. Louis and. Louisiana, Mo., by
the Division of Control Investigations of the Bureau. The University
of California Citrus Experiment Station supplied all oriental fruit
moth eggs and hibernating larvae of California origin. Hibernating
larvae from New Jersey were supplied by the Division of Fruit Insect
Investigations of the Bureau. Stark Bros. Nursery, Loulsiana, Mo.,
rpsisted in taking nursery-stock storage shed temperatures end humidity
records, which are shown in figure 1.

The experimental fumigations were performed in portable chambers,
which were in excellent condition. Commercial cold-storage facilities
were utilized for the storage of P-ples. Except where otherwise noted,
all fruits were purchased from local sources, pnd were especially se-
lected for condition.

All dosages are expressed in pounds of methyl bromide per 1,000
cubic feet of space. For conciseness the dosage schedules are abbre-
viated as indicated in the following example: A schedule of 3 pounds
per 1,000 cubic feet for an exposure of 2 hours at 70F. is shortened
to 3 lb./2 hr. at 70.

As certain portions of the experimental tests were finished, cor-
roborative tests were made in California to check the results under
their conditions. These tests were reported by Armitage and Steinweden
in March 1945. 3/

&/Armiitage, H, H., end Steinweden, J. B. Development of methods of
fumigation for control of the oriental fruit moth. Dsc. 1944 Mar. 1945.
Unpublished report of Anaheim Station, California State Department of
Agriculture.








The results are presented under the following headings: (1) Fumi-
gation of fresh-fruit hosts of the oriental fruit moth, (2) mortality
of larvae exposed to cold storage, (3) fumigation of hibernating larvae,
and (4) tolerance of fruits to methyl bromide fumigation.

FUMIGATION OF FRBESH-FRUIT HOSTS
OF THE ORIENTAL FRUIT MOTH

All studies relative to the fumigation of fresh-fruit hosts were
limited to the summer broods of the oriental fruit moth. The results of
tests with each stage of this insect are given. Overwintering larvae were
considered only in their relation to dormant nursery stock and are the
subject of another section.

Larvae

Tests in an effort to develop fumigation schedules for larvae of
the oriental fruit moth embedded in fresh fruit were first made in the
summer of 1943. At first green apples were infested by enclosing them in
cages with infested peach twigs; later naturally infested fruit was ob-
tained.

Dosages of methyl bromide ranging from 1 to 2 pounds per 1,000 cubic
feet were used at temperatures of 60 and 700F. The results of these
tests ere given in table 1. Complete mortality occurred at all dosages
except 1 lb./2 hrs. at 60, where 1 larva and 2 pupae survived.

In 1944 plans were made to infest fruit artificially so that greater
quantities would be available. Through the courtesy of the University
of California Citrus Experiment Station, eggs, deposited on sheets of wax
paper, were supplied at frequent intervals (2 to 3 days) by air mail.
Bushel lots of apples were infested by placing a small piece of wax paper
containing about 6 eggs in contact with each apple. Nineteen bushels in-
fested in this manner proved to have an average infestation of slightly
more than one larva per apple. Apples were ready for use in fumigation
tests in about 6 days if immature larvae, or about 12 to'15 days if
mature larvae, were desired. Fifty-nine tests- were made with dosages
ranging from 0.5 to 2.5 lb. at temperatures from 40 to 807. A total
of 4,247 apples were used, containing 4,455 larvae.

It was considered desirable to develop fumigation schedules suitable
for the treatment of fruit that had been refrigerated, or placed in cold
storage, as well as for freshly picked fruit. A minimum of 40OF. was
used, since it was considered that most fruit coming from cold storage
would be at approximately that temperature by the time it had been made
ready for fumigation. The results of these tests are given in table 2.

The minimum dosage schedules causing complete mortality of larvae
were 0.75 lb./2 hr. at 800, 700, and 600F. and 1 lb./2 hr. at 50 and 400.
The location of surviving larvae within the apples varied. No particular
area, such as the center, was noted where survival would most likely occur.


ft







-4-


Table 1.--Results of 1943 tests on methyl bromide fumigation of fresh
fruits infested with oriental fruit moth larvae. Fumigation for 2
hours unless otherwise noted
z
Treatment Total : Condition of larvae

Temperature* Dosage : Date : ruit : Total 2 Mortality

".Pounde Number umber Percent

Apples

70 2 5/13 6 32 100
1.5 5/13 6 27 100
5/19 16 94 100
5/19 V 16 75 100
60 2 6/23 19 67 100
1.5 6/23 20 75 100
1 7/20 29 9 /89

Peaches Z/
70 1.5 7/26 37 12 100
7/28 75 16 100
1 7/26 33 22 100
8/4 32 5 100
60 1.5 8/12 100 12 100

Pears Z/
70 1 8/4 32 5 100


I/Fumigation 1.5 hours.
2/Two live pupae also found, under skin of apples.
/Naturally infested fruit.






- 5 -


Table 2.--Results of 1944 tests with 2-hour methyl bromide f."aign-
tion of fresh fruit infested with oriental fruit moth larvae


Treatment 0 Toa 0 CondItion of larvae
------- osae" ests"otal Torl Applesy
Tenperature: Dosage : tests 2 Total : Mortality
0 0


Pounds


Number


0.5
.75
1.0

.5
.75
1.0
1.25

.5
.75
1.0
1.5
2.0

.5
.75
1.0
1.25
1.75
2.0
2.5

.5
.75
1.0
1.25
1.5
2.0
2.5


Number


34
280
490

92
183
441
500

53
63
112
626
150

40
39
66
43
300
39
22

41
42
44
64
46
413
24*


Number

35
17a
519

70
161
y.'!
686

19
38
57
644
189

21
19
50
48
427
51
2&

31
39
35
29
20
650)
49


Percent

91
100
100

91
100
100
100

89
100
100
100
100

52
63
100
100
100
100
100

74
92
100
100
100
100
100






-6-


No difference in reaction was observed between the different larval
stages.

The mortality obtained in artificially infested apples was compared
with that in naturally infested fruit collected near St. Louis. These
data are given in table 3. The naturally infested fruit required slightly
higher dosages than the artificially infested fruit. Single survivors
appeared with a dosage of 1 lb. pt 500 and 600F. and it would apparently
require a dosage of 1.25 lb. for complete kill at these temperatures.
With a dosage of 0.75 lb., survival occurred at 700, indicating that a
dosage of 1 lb. would be necessary at this temperature level.

Fumigations at the 400F. temperature level would probably be on
fruit either refrigerated or from cold storage. In order to determine
whether a period of cold storage would change the susceptibility of
larvae to fumigation, a series of tests was made wherein infested apples
were removed from cold storage at weekly intervals and fumigated with a
dosage of 2 lb./2 hr. at 400. The apples were placed in storage Septem-
ber 25, 1944, and contained both mature and immature larvae.

The results are given in table 4. No survivals occurred. However,
all larvae in the check samples were deed from cold storage alone at the
end of the eighth and ninth weeks.

Eggs

The results of fumigation tests with oriental fruit moth eg-gs, at
Beltsville, Md., in 1939, reported in 1942, 4/ showed some hatching with
schedules of 1.5 and 2 lb./4 hr. at 60C'. Later it appeared that these
schedules might be excessive because of certain errors connected with the
use of too small a fumigation chamber.

Therefore, further tests were conducted in 1944 with eggs .supplied
by air mail from the University of California Citrus Experiment Station.
Pieces of wax paper upon which eggs had been deposited were fumigated
without other load in a 20-cubic foot temperature-controlled chamber.
Since experience had shown that the displacement by a load is usually
greater than the absorption by it, results in an empty chamber are valid.
Tepts were made between 500 and 707. with exposures of 2, 3,and 4 hours
in an attempt to develop fumigation schedules for eggs comparable to
those used for larvae in fresh fruits. A check sample was kept from
each shipment of eggs. The results are given in table 5.



4/Johnson, A. C., Livingstone, R. M., and Bulger, J. V. Methyl
bromide fumigation to control oriental fruit moth on dormant nursery
stock. Jour. Econ. Ent. 35! 674-677. 1942.









Table 3.--Comparison of mortality obtained by fumigation of artificially
and naturally infested fruit. (Numbers of larvae involved Pre given
in parentheses)


Mortality at treating temperatures of--


Dosage :


40F.


600F.
*


Percent


701F.


80.F


Percent


Artificially infested apples,


treated July 17 to Oct. 31, 1944


100 (370)
100 (161)
87 (69)


100 (522)
100 (176)
94 (17)


Naturally infested pears,


100oo (8)
100 (7)
o100 (8)


100 (7)
100 (5)


treated Nov.


100oo (8)
90 (10)


1 to 7, 1944


100oo (8)
100oo (10)


Naturally infested apples,


100 (8)
100 (16)
o100 (8)


100 (12)
88 (8)


treated Nov. 14 to 19.


90 (10)
85 (7)


100 (8)
91 (11)


1.5
1.25
1.0
.75
.5


100 (20)
100 (29)
100 (35)


100 (48)
100 (50)
97 (36)


100 (58)
100 (40)
90 (19)


1.75
1.5
1.25
1.0
.75
.5


o100 (6)
100oo (7)


1.75
1.5
1.25
1.0
.75
.5


1944


100 (12)
100 (10)


50 OF. :
f


Percent


Percent







-8-


Table 4.-Results of weekly fumigations of infested apples from cold
storage, with a dosage schedule of 2 lb./2 hr. at 400.

: Check samples PFumigated samples
Storage ,__... ....
period Apples :. a ortality Apples : Total :Mortality
peioe larvae larvae

Num fber KA Perct Number Number Percent

0 12 9 0 -.
1 -- 12 10 100
2 -- 12 8 100
3 12 6 100
4 12 9 100
5 -- 12 13 100
6 12 10 90 12 8 100
7 12 7 86 12 6 100
8 24 16 100 12 7 100
9 51 21 100 --







-9 -


Table 5.--Hptching of eggs fumigated with me':' i- -,!milde et temper-
atures between 50 and 70F. Tests conduct' J,.rch to June, 1944.


Treatment

Temperature Dosnze Exoosure
S Pquqd^t Hj -H _-._.,-.r,.


1.5



2



2.5



3


Result of hatching
T- tal gg .
*:.-- s ha.tc i
.. Percent


1,.-. 9
413
,::)3

808
379
,_.36


168
190

A)
169
166

228

755
191
211

414
168
197

n 2
"1,1,9


44.6
163


1,5


1.5


4 1


1,160
407
2P5

1, r5F7
170
188


82.3
63.]
4.9

32.3
0
0

0.7
0
0

0
0
0

0

36.3
1,5
0

24.4
0.5
0

0.9
0
0

0
0

0

7.8
2.4
0

0.6
0
0












Table 5.-- Continued


*
Temperature:



60



65













70






Checks


S


Treatment

Dos age
Pund P

2

25

1



1.5



2

2.5

1

1,5

o3


*
**
* 5
:Exposure
Honra

2

2

2
3
4

2
3
4

2

2

2

2

2


m


Total
tests

N3mer

3

3


3
1
1


3
1
1

2

1

2

2

1

44


*
Resulted of hatching
: Total : BggE
Seggs : hatching
Nub er PerceWt

690 0

670 0

824 16.0
191 0
142 0

663 0
139 0
A,1 0

431 0

215 0

443 0.4

457 0

200 0

5,271 93,6


II I L I I I III {


- 10 -






- I1 -


It is evident from the results shown thpt the e;- -sure ;sir
can be shortened to 2 hours to conform with schedules for the i
ggtion of larvPo. Te mininAum schedules for the 2-honr exposure t
which no eggs hatched were as follov.ws:

CPU Pounds

50 ?.5
55 25
60
6? 1,,5
70 1.5

Pup e

Specific tests were nct mp with pupae. However, it hs '-
observed that, wherever our).'e were included with larvae, the.
erally showed *--rter mortality then did the lerve. For eT--le
test with a dosage of I lb./2 hr. Pt 60CF. showed 14 deno ilrrve oat
o tPotql of 18, nr;d complete mortiity rmong 25 pupae.

A&du lts

No further tests were made against adults s'nce it h.d been pre-
viously shown thit they vere vexi' susceptible to methyl bromnidle fun.L-
gation (0.25 lb./4 hr. st 70OF.).

TDiscussion

Dosage schedules for fresh fruits should oe sufficient to ) to
not only larvae, but eb,,j and ;u'De as well. While pupae re -eldom
found on the fruit, they could be present in containers. Adults prob-
ably would not be present, but they are the easiest to kill of all
stages of this insect.

A review of the results obtained with artificially infpst fruit
(table 2) shows that complete mortality was obtained with the foll ,-0v .
schedules:

0.75 lb./2 hr. Pt 80t, 700, and 50OF.
1 lb./2 hr. -t 50' end 40c

Tests with naturally infested fruit (tables 1 and 3) show tht
slightly higher schedules qre needed, Ps follows:

1 lb./2 hr. at 70CF.
1.25 lb./2 hr. at 500 and 600







- 12 -


Tests with ecs (table 5) indicated theto r -resistant
than summer-brood larvae, and the followi- scu the mini-
mum causing complete mortality;

2.5 lb./2 hr. at 50t.
2 lb./2 hr. at .'r
1.5 lb./2 hr. at '


It would appear th-. on th is of
that a ssti factor 'eris of tion
feasted with oriental fruit moth or ec


]- t* in
e for fresh fruit in-
f s would x1 e"


Pj./ hr. at ',.**_ .
2.5 lb./2 .r at Y':
2 lb./? hr. at r,.'
1.5 lb,/2 hro at
I !b./2 hr. at


.-^, to the 'sccvery of the -ret h i ifornia
in 1942 id the si:it., ent ,.-; of r. :'tl o o f this
insect in 1943 during which tons of fruit P of contisrs
were fumi:-.at.-d, it was necessary to select do- -c a for that
purpose before amcih of this experi.T,',tal work was :-- ;o .e1.. The
dosri-e schedules set up by California in ''- of 1.5 Ibo/2 hr. at 70e.,
2 lb./2 hr. at 65, rn2 2.5 lb,2 hr, t e. t ally con-
firmed by the results of the lrese t oes-

.dR'I'TALITY OF LARV.A X:"._ .. .,-...

Following the discovery tht the viability of larvae in apples
held in cold storage was seriously affected as shown in the check sam-
ples-in table 4, tests were .-:onifi.^tetd to obtain further evidence on
this point. Two bushels of infested '-ipples placed in cold storage on
September 18, 1944, were sam 0nle t weel'l: int-- for 10 n- : and
the condition of the larvae was noted. One bushel conta.':: mostly
immature larvae, and the sec',-d mostly mature .] t e.

The result of the we.i-:-" 7 :tionp e in. 6.
There was no evidence of ievel-'.!' t f the t after en-
tering cold storage, and all were det d in ..'c.lee ...... e. at the 5th
to the 10th weeks. The mature lePr-; e were hardier, and one survived
in the sE.:Jple examined the 10th we-l, althcLh ell others were dead
in the sample taken the 9th w"ek. .-re wa no evidence of migration
from the apples during the sto'-,.e period,


5/Armit--:e and Steinwed-en (set- footnote, .-..-e in California
had no survivors in artificially 'i est-.- .1r-t -. at the
following schedules, in series repeated four times on JD-zc, 5, 1944,
Jan. 2, Jan. 28, and Feb. 24, 1945: 1 lb. at 80F., 1,;5 lb. at 700,
1.5 lb. at 30', 1.75 lb. at 50, end 2 Ib. at .;






- 13 -


Table 6.--Mortality of larvae in infested apples held. for various
periods in cold storage at 34 to 36F.


: : Immature larvae Mature larvae
Storage : Apples : ____________
period : examined :Total : Mortality' Total : Mortality

Wek Number Number Percent Number Percent

0 12 21 0 8 0
1 12 14 0 13 0
2 12 11 36 5 20
3 12 11 64 13 15
4 12 19 95 8 38
5 12 8 100 6 83
6 12 12 100 9 89
7 12 11 100 11 91
8 12 7 100 15 93
9 24 13 100 21 100
10 1 17 100 30 93


1/36
2/54


apples examined.
apples examined.


LIBRARY
STATE PLANT BOARD






- 14 -


Since some survival occurred after storage for 2 1/2 months,
further tests were made for periods of 3 and 4 months. At 3 months
two temperature levels were compared, 330 to 341F. and 35 to 350.
The 4-month test material was stored at 35 to 36c.

The mortality in the 3 lots was almost, but not quite, complete.
In the bushel stored for 3 months at 350 to 36CF.,4 ltva larvae were
recovered from a total of 129. In attempts to rear out these larvae
at room temperature, one died the 4th day, one the 5th, and the third
the 7th day. The fourth larva survived to maturity. Prestorage
examination of a sample of 12 apples showed 19 live larvae and none
dead. The bushel contained 195 apples of which 35 were soft and
rotten at the end of the experiment.

In the second bushel stored for 3 months, at 33 to 34F.,'1
live larva was found in a total of 214. This larva was weak and died
6 days later. Prestorpge examination of a sample of 12 apples showed
8 live and no dead larvae. The bushel contained 219 apples of which
19 had rotted.

In the bushel stored for 4 months at 35 to 36F., 1 moribund
larva was found in a total of 176. It died 12 days later. The
bushel contained 165 apples, 9 of which had rotted.

It is evident from these tests that there is little danger of
oriental fruit moth larvae being disseminated by fruit which has been
subjected to any considerable ea.ount of cold storage at temperatures
below 361F. On the other: hand, a cold-storage treatment would not
appear to be entirely acceptable as a means of certifying fruit under
oriental fruit moth quarn;ntines.

The occurrence of live hibernating larvae in used baskets often
utilized as containers for fru-ait to be certified under oriental fruit
moth quarantines is an additional complication. Even though the bas-
kets would be subjected to fumigation at schedules used for summer
broods of thip insect, a hazard would still exist, since the dosage
schedules for infected fruit are considerably less than those for
hibernating lnrvae.

FUMIGATION OF HIBERTATIITG LARVAL

Eyreria ental Work 1938-40

The dosage schedules now required by member States of the Western
Plant Board, with respect to nursery-tree hosts of the oriental fruit
woth, are based on experimental work carried on by the Bureau of Ento-
mology and Plant Quarantine from 1938-40 (See footnote p.6). The
first tests were conducted at Moorestown, N. u., in 193P, with hiber-
nating larvae provided by H. W. Allen and associates of the Bureau.
The larval material was held at a storage temperature of approximately
401F. until treated. After treatment mnny lots were divided, the







- 15 -


larvae in one lot being removed from their cocoons following treat-
ment and held for observation. The remaining larvae were stored in
an outdoor shelter and observed in periods ranging from 2 months to
2 weeks. It was found that the mortality of the larvae held for
later examination was greater than of those removed from their co-
coons soon after treatment.

Tests were made at Beltsville in the winter of 1938-39, with
larvae from the same source, but kept in outdoor storage. Mortality
occurred at lower dosages than when stored at a constant of 40OcF.,
and no apparent difference existed in lots removed from cocoons
immediately after treatment, and those held for a considerable period.

The original recommendation in 1938 for treatment was for a
dosage of 3.5 lb./4 hr. at 701F. In 1939 this was modified to 2 lb./
4 hr. at 70, or 3 lb./4 hr. at 60. These latter schedules have
been in effect since that time.

Recent Experimental Vork

In 1943, further studies were initiated for two purposes: (1)
To attempt to reduce the dosage schedules then in effect, and (2) to
attempt to develop fumigation schedules for lower temperature levels.

Approximately 15,000 hibernating larvae -'ere provided for these
tests by the University of California Citrus Experiment Station.
Upon their arrival on December 6, 1943, these were placed in storage
at 32F., and the temperature was increased later in the season to
48 to 50 in order to reproduce to some extent conditions comparable
to those in nursery storage sheds.

Six series of tests were made with these larvae between February
and May, each series including fumigation at temperatures between the
current minimum level and 700F. The larvae were conditioned to the
temperature at which they were fumigated for the periods indicated in
table 7. Past experience in other studies had indicated that with
each temperature drop of 10, the dosage of methyl bromide needs to
be increased. Since the tests in 1938 had shown the need for an in-
crease of 1 pound per 1,000 cubic feet in dropping from 70 to 60,
the dosage increase was used in the first series of tests made
February 18 to March 2 i.e., 2 lb. at 70. 3 lb. at 60, 4 lb.
at .50c. 5 lb. at 40, and 6 lb. at 30. Before the second series
was started, it became evident that this rate of increase was insuf-
ficient, so the dosages were changed to 4 lb. at 50c, 6 lb. at 400,
and 8 lb. at 30. The results of these tests are given in table 7.

Table 8 contains a summary of the essential data for tests of
2, 3, and 4 hours' duration. It is evident from table 7 that under
the conditions of these tests, with 4-hour exposures, that dosages
of 8 lb. at 30c, 6 lb. at 400, and 4 lb. at 5OcF. were not sufficient






- 16 -


Table 7.--Adults emerging after treatment of hibernating larvae at
intervals during the storage season. Larvae of 1943 California
origin. Samples of series A contained approximately 20 larvae
each, of series B about 25, and of series C-F about 50 larvae.


Treatment "Storage Condi-: Adults emerged from lots exposed for--
-'temper- tioning:" .......... .
Temper-: teae: tr peionn 2 : 2.5 : 3 : 3.5 : 4
Dosage nature period h
ature e :Q3o hours hours : hours h hours


C. Pounds OF.


Hours Number Number Number


Number Number


Series A, treated Feb. 18-Mar. 2, 1944


6
5.5
5
4.5
4
3.5
3
2.5
2


Series B, treated Mar. 7-24. 1944


8
7
6
5
4
3.5
3
2.5
2


Series C, treated Apr.


None
3
3
None
16
16
36
48


5-20, 1944

18
19
15
1
0
0
0
1


8
6.5
5
4
3.5
3
2.5
2






- 17 -


Table 7.--Continued


Treatment Storage Condi-: Adults emerged from lots exposed for--
temper-: tioning* -. ....... .......
Temper- :D .*... p eriod' 2 : 2.5 : 3 : 3.5 : 4
nature rFhours t houre :e hours hours : hours
*IF Ponds 01P Ho-ars Number. Number, Numbe Number- umber


Series D, treated Apr. 5-20, 1944


7.5
6.5
5
4
3.5
3
2.5
2


None
3
3
None
16
72
60
72


Series E, treated Apr. 29-May 3, 1944


Series F, treated May 4-11.


50
50
48
48
50
!/


15
None
15
36
36
48


5
4
3.5
3
2.5
2


1944


I/Taken out of storage at 48F. and subjected to room temperature
varying from 55 to 70 for one week, then held at 70 for 48 hours.







- 18 -


Table 8.--Mortality of hibernating larae of 1943 California origin
following treatment at intervals during the storega season; data
of table 7 summarized for each treatment temperature and exposure


Treatment


Temper- :
ature
IF.

30


35




40



45


50

55


Dosage
Pounds


: Average
Total : larvae
tests : per
ube : test
Number Number


6
8

5.5
7
7.5
8

5
6
6.5

4.5
5

4

3.5


Mortality of larvae
......exposed for--
2 : 3 : 4
hours : hour hQurs.
Percent Percent Percent


43
100


48
100
79

91
63


90
100
75

100
94


100

100


2.5


18 40 90


99 100


70 2






- 19 -


to produce complete mortality in all series. The schedules of 3 lb.
at 600. and 2 lb. at 70 did, however, produce complete mortality.
It is also noted that as the treatment was done later in the season,
the larvae tended to become more resistant to methyl bromide fumiga-
tion. This is contrary to results obtained in previous tests.

The program was amplified further in 1944-45. The previous
conflicts in results could have been due to the source of larvae or
to the conditions of storage. Therefore, larvae were obtained from
both California and New Jersey and stored under (1) cold-storage
temperature conditions, (2) simulated nursery-stock storage conditions,
and (3) outdoor winter conditions. For cold-storage conditions the
larvae were placed in commercial apple storage. For simulated nursery-
stock storage the larvae were placed in a thermostatically controlled
mechanical refrigerator which was periodically adjusted so as to
follow the weekly averages of hygrothermograph records taken concur-
rently in a nursery-storage shed in Louisiana, Mo. The weekly mean
temperature in this selected storage shed, Pnd the current outdoor
temperature mepns are given in figure 1. The relative humidity in
this shed remained Pt 100 percent until almost the end of the season.
For outdoor conditions the larvae were placed in a battery jar in a
sheltered location outdoors at St. Louis.

Tests with larvae of New Jersey origin.--Approximately 10,000
hibernating larvae were received from Moorestown, Y. J., on November 5,
1944. These were divided into four equal portions and stored as
follows: Portion 1 cold storage at 321 to 38F., portions 2 and 3 -
simulated nursery-stock shed storage, and portion 4 outdoors.

Larvae from cold storage (portion 1) were fumigated at approxi-
mately monthly intervals frdm January 25 to April 25. Since some
tests in epch series were at temperature levels different from that orf
storage, the larvae were conditioned for a period prior to fumigation.
The original series of dosage schedules, ranging from 2 lb. at 70 to
6 lb. at 320F. was again used.

In each test the larvae were removed from their cocoons follow-
ing fumigation, and kept in petri dishes for observation. Final re-
sults were based on the emergence of adults from these larvae.

The results are given in table 9. They showed no tendency for
the larvae to become more 'resistant to fumigation as the season pro-
gressed. This was a reversal of the results given in table 7. In
series A, survival occurred at 3201. 4ith all exposures and at 40
and 70 with 2-hour exposures. In series B, one month later, a single
survival occurred at 40 with a 2-hour exposure. In the remaining
two series, no survivals occurred in any test.






-20-


Table 9.--Adults emerging after treatment of hibernating larvae
at intervals during the storage season. Larvae of 1944 New Jer-
sey origin, kept in epple-storage rooms at a temperature of
326 to 3407. from Nov. 5, 1944, to Feb. 26, 1945, and at 36 to
38 from Feb. 27 to end of tests. Samples contained from 19 to
75 larvae each.


Treatment


Temperature Da
Temperature: Dosai


SCondi-
-- tioning
;e period


. Pounds Hours


: Adults emerged from lots
:exposed for--
2 3 4
hours : hours g hours
Number Number Number


Series A, treated Jan. 25.27, 1945


32 6
40 5
50 4
60 3
70 2
Check (untreated) . .


0 12 25 9
.75 1 0 0
1.5 0 0 0
2.25 0 0 0
3 2 0 0
. .* . ... 10 adults from 36 larvae


Series B. treated Feb. 27-Mar. 3, 1945


32 6
40 5
50 4
60 3
70 2
Check (untreated) . .


0 0 0 0
.75 1 0 0
1.5 0 0 0
2.25 0 0 0
3 0 0 0
. . . 9 adults from 37 larvae


Series C, treated Mar. 26-30, 1945


40 5
50 4
60 3
70 2
Check (untreated) . . .


0 0 0 0
.75 0 0 0
1.5 0 0 0
2.25 0 0 0
V * . . 1 adult from 61 larvae


Series D, treated Apr. 25-28, 1945


40 5
50 4
60 3
70 2
Check (untreated) . .


0 0 0 0
.75 0 0 0
1.5 0 0 0
2.25 0 0 0
. . .. .. .12 adults from 29 larvae






- 21 -


A similar series of tests was made with larvae held under
simulated nursery-stock storage shed conditions.

It was desired to compare the mortality of larvae taken from
storage following fumigation, with that of larvae replaced under
nursery-stdck storage conditions for the remainder of the season.
To do this, a double amount of lerval material (portions 2 and 3)
was included in each test. The larvae from one portion were removed
from their cocoons following fumigation, and held in petri dishes
at room temperature for observation. The remaining larvae were re-
turned undisturbed to simulated nursery storage and held until they
were about to pupate (&s indicated-by examinations of check samples),
before they were removed from their cocoons. This additional stor-
age period amounted to 98 days in series A, 63 days in series B, 43
days in series C, 14 days in series D, and 6 days in series E.

The emergence from both portions is given in table 10. The
number of adults was less from larvae returned to storage than from
those placed under observation immediately following fumigation.






- 22-


Table 10.--Adults emerging after treAtment of hibernating larvae at
intervals during the storage season. Larvae of 1944 New Jersey
origin, kept in simulated nursery-stock storage. Samples contained
approximately 30 le.rvae each in series A, 5, and C, and 40 larvae
and pupae mixed in series D and 3.


: Adults emerged from : Adults emerged from
Treatment : Condi- : lots removed to : lots replaced in
________ tioning : room temperature : nursery storage
Temper-: : period : 2 : 3 : 4 : 2 2 3 : 4
ature : -Dosage :hours hours = hours hours t hours : hours
OF. Pounds Hourl ib Numbuer # v


Series A, treated Jan. 22- 24, 1945


32 6
40 5
50 4
60 3
70 2
Check (untreated)


0.75 11 19 17 10 5 9
0 1 11 4 3 0 2
.75 2 0 0 0 0 0
1.5 0 0 0 0 0 0
2.25 1 0 0 1 0 0
. . 9 adults from 28 larvae 9 adults from 30 larvae


Series B, treated Feb. 22-Mar. 1, 1945


40 5
50 4
60 3
70 2
Check (untreated)


0 2 8 0 0
.75 0 0 0 0
1.5 0 0 0 0
2.25 0 0 0 0
S. 7 adults from 28 larvae 5 adults

Series C, treated Mar. 19-20, 1945


0 0
0 0
0 0
0 0
from 30 larvae


50 4
60 3
70 2
Check (untreated)


.75 4 1 0 4 0 0
0 0 0 0 0 0 0
.75 0 0 0 0 0 0
. 6 adults from 23 larvae 10 adults from 30 larvae


Series D. treated Apr. 17-20, 1945


50 4
60 3
70 2
Check (untreated)



50 4
60 3
70 2
Check (untreated)


.75 1 0 0 5 0 0
0 0 0 0 0 0 0
.75 0 0 0 0 0 0
S. 20 adults from 41 larvae 13 adults from 27 larvae
and pupae and pupae
Series E, treated Apr. 30-May 3, 1945

.75 1 0 0 0 0 0
0 0 0 0 0 0 0
.75 0 0 0 0 0 0
. . . . 3 adults from 3 pupae






- 23 -


The mortality following fumigation of larvae kept in cold stor-
age can be compared with that of larvae kent in simulated nursery-
stock storage by referring to table 9 and the results of immediate
examinations given in table 10. There were fewer instances of sur-
vivals from larvae held-in cold storage than from those stored under
simulated nursery-rtock conditions. In table 9, series A, there were
no survivals from Z-Pnd 4-hour exposures at 40CF., or after 2 hours -at
500, none in series B after 3 hours at 400, none in series C after
2 and 3 hours at 50, and none in series D after 2 hours at 501. Sur-
vivals occurred at all of these points with larvae held in simulated
nursery-stock storage.

Additional tests were made April 9 to 11 with larvae stored out-
doors (portion 4). These larvae had been exposed to normal winter
temperatures for approximately 5 months. Tests were made at 500,
600, end 70?F., with exposures of 2, 3, and 4 hours at each temperature
level. No adults emerged from any of the tests. The check samples
yielded 135 adults from 222 larvae and pupae.

Tests with larvae of California origin.-Larvae were received from
California in three shipments on November 15, 1944, December 29, 1944,
and January 26. 1945. Since this made the prefumigation storage dif-
ferent, seasonal series of tests were made with each lot. The November
shipment was paired with the New Jersey material so that the series of
tests would be directly comparable. This shipment was divided into
three portions, and stored with the New Jersey larvae as follows:
Portion 1 cold storage at 32 to 38C7., and portions 2 and 3 sim-
ulated nursery-stock shed storage.

Larvae from cold storage (portion 1) were fumigated at approxi-
mately monthly intervals in the spme tests with New Jersey larvae.
The results of these tests ere given in tPble 11. There was no evi-
dence that there was any appreciable change in the resistance of the
larvae with the sfvpnce of the season. With the 40-onmrcent schedule
for 3 hours a single survivor occurred in series B, C, and D. With
the exception of survival at 70F. for 2 hours in series A, no sur-
vival occurred in any series at any schedule -t 500 or above.

Series of tests were also made with the november shipment of
larvae held under simulated nursery-stock storage. These were again
paired with New Jersey larvae from the same storage in series of tests
at intervals through the storage season. A double Amount of larvae
was used (portions 2 and 3), one portion being removed from the. co-
coons following fumigation, and the other being replaced in simulated
nursery-stock storage until nearly ready for pupation. The emergence
from both portions is given in table 12. The mortality was greatest
when the treated larvae were replaced in nursery-stock storage, both
from the standpoint of the number of tests showing no emergence, and
in the fewer numbers of adults emerging.









Table ll. -Adults -nergii.i .-: treaudit 0of L la 1Vae
at inrer',1s -',.i:-tig the st,-g- se.. of )-944 Califor-
nia origin, shipped Nov. 15, aP- kept .ri appleoiorege rooms at
a temperature of 32 to 34F. iu-til ,b. *., ,uc at 36 to 38
from Feb. 27 to end of the zsts. S-^ples contpAned from 24 to
70 larvae each.


Treatment


~Do *


Temperature
Temperature:


OF -aMAR RL.fi KfM';t


tic.: :
per.C <


Adults ew eit ti. from lots
__oco.,:4. for--


2
hours


S
1)~~I :


Iuinb er


Series A, tre-ted Jan. 765-2. 1945


32 6
40 5
50 4
60 3
70
Check (untreated) . .


0 10 16 12
5 0 0
1.5 0 0 0
2.C 0 0
S4 0 0
.. .. .. . 11 adI.ts from 25 larvae


eries B, treaeJ Feb. --!L::'. 3. 1945


6
40 5
50 4
60
70
Check (untrLted) .


Serl es C.

40 5
50
60 3
70 2
Check (untreated) . .


0

1.5

3
9 0 9t 9


1 1 0
0 1 0
0 0 0
S0 0
0 0 0
. . 22 ,]' t from 25 larvae


treated MA.r, ?6-30, 1945


0
0 -
.2**,


0 1 0
0 0 0
0 0 0
S0 0
. . 10 Fd,ilts from 53 larvae


Series D, treated Apr. ?5-56, rS,


40 5
50 4
60 3
70 2
Check (untreated) . .


0 4 1 0
.,5 0 0 0
1.5 0 0 0
S25 0 0 0
. .. . .* 15 adults from 27 larvae


4
hours
Number






- 25 -


Table 12.--Adults emerging afteLe treatment of hibernating larvae at
intervals during the storage season. La:-vue of 1944 California
origin, shipped Nov. 15, and kept in simulated nursery-stock storage.
Samples contained from 17 to 29 larvae each in series A, B, wua C, CUa
from 13 to 54 larvae and pupae mixed in series D and E.


: : Adults emerged from Adults emerged from
Treatment : Ccndi-& lots removed to : lots replaced in
: tioning: room temperature nursery storage
Temper-: : period: 2 : 3 : 4 : 2 : 3 : 4
ature : Dosage: : hours : hours : hours: hours ; hours : hours
CF. Pounds Hours NMber umber Number Number Number Number

Series A, treated Jan. 2P-24, 1945


6
5
4
3
2
(untreated)


0.75 11 25 17 11 4 10
0 19 19 15 6 5 I
.75 1 4 2 1 0 0
1,5 5 0 0 0 0 0
2.25 7 0 0 0 0 0
* . 12 adults from 27 larvae 8 adults from 24 larvae


5
4
3
2
(untreated)


Series B, treated Feb. 22-Mpr. 1, 1945

0 5 7 0 0 0
.75 0 0 0 0 0
1.5 0 0 0 0 0
2.25 0 0 0 0 0
. 9 adults from 24 larvae 10 adults from


0
0
0
0
24 larvae


Series C, treated Mar. 19-20, 1945


50 4
60 3
70 2
Check (untreated)


.75 7 5 1
0 0 0 0
.75 0 1 0
. 11 adults from 25 larvae


1 0
0 0
0 0
10 adults from


0
0
0
24 larvae


Series D, treated Apr. 17-20. 1945


50 4
60 3
70 2
Check (untreated)


.75 5 2 0
0 1 0 0
.75 0 0 0
. 22 adults from 41 larvae
and pupae


1 0
0 0
0 0
28 adults from
and pupae


0
0
0
42 larvae


Series E, treated Apr. 30-May 3, 1945


50 4
60 3
70 2
Check (untreated)


.75 0 1 0 5 0 0
0 0 0 0 0 0 0
.75 0 0 0 0 0 0
* . . . 6 adults from 11 larvae and pupae


32
40
50
60
70
Check


40
50
60
70
Check






26 -

Additional tests with larvae kept imder simulated nursery-
stock storage were made with the December and January shipments.
The results of these are given in tables 13 and 14. In these tests
the additional storage amounted to 48 days for series A, 26 days
for series B, 15 days for series C, and 6 days for series D. These
series of tests showed less survival than the lIovember shipment.
The cause for this difference is not known. Less emergence occurred
from larvae replaced in storage, as was the case in the tests with
the November shipment.








Table 13.--Adults emerging after treatment of hibernating larvae at
intervals during the dormant season. Larvae of 1944 California
origin, 'shipped Dec. 29, and kept in simulated nursery-stock
storage. Samples contained from 15 to 68 larvae each.


: Adults emerged from : Adults emerged from
Treatment Condi-: lots removed to lots replaced in
:tioning: room temperature nursery storage
Temper-: Dosage period: 2 : 3 4 2 3 4
nature t : hours ; hours : hours hours : hours : hours
r, Pounds Hours be Nu bomber r NNumber umber Number Number

Series A, treated Mar. 14-16, 1945


50 4
60 3
70 2
Check (untreated)


0.75 12 7
0 2 2
.75 8 0
* 18 adults from 64


0
0
0
larvae


3 0
1 0
2 0
9 adults from


0
0

60 larvae


Series B, treated Apr. 4-7, 1945


50 4
60 3
70 2
Check (untreated)


.75 0 0 0
0 0 0 0
.75 0 0 0
* 6 adults from 53 larvae


0 0
0 0
0 0
12 adults from 60


Series C, treated Apr. 17-20, 1945


50 4
60 3
70 2
Check (untreated)


.75 0 0 0
0 0 0 0
.75 0 0 0
S. 10 adults from 20 larvae


0 0
0 0
0 0
0 adults from


0
0
0
9 larvae


Series D, treated May 1-3, 1945


50 4
60 3
70 2
Check (untreated)


.75 0 0 0 0 0
0 0 0 0 0 0
.75 0 0 0 0 0
*. . * 0 * *. 6 adults from 16 larvae


0
0
0
larvae







-28-


Table 14.--Adults emerging after treatment of hibernating larvae at
intervals during the storage season. Larvae of 1944 California
origin, shipped Jan. 26, 1945, and kept in simulated nursery-stock
storage. Samples contained from 41 to 72 larvae each.


S: Adults emerged from : Adults emerged from
Treatment : Condi-: lots removed to : lots replaced in
: tioning. room temperature : nursery storage
Temper-: Dosge: period: 2: 3 4 2 : 3 4
nature : b hours ; hours : hours hours : hours : hours
F. Pounds Hore Number Number Number Number Number Number


50 4
60 3
70 2
Check (untreated)


Series A, treated Mar. 14-16, 1945

0.75 11 2 1 2
0 2 0 0 0
.75 1 0 0 0
- 23 adults from 66 larvae 10 adults


Series B, treated Apr. 4-7, 1945


0 0
0 0
0 0
from 60 larvae


50 4
60 3
70 2
Check (untreated)


.75 0 0 0
0 0 0 0
.75 0 0 0
. 10 adults from 62 larvae


0
0
0
10 adults


0 0
0 0
0 0
from 60 larvae


Series C, treated Apr. 17-20., 1945


50 4
60 3
70 2
Check (untreated)


.75 0 0 0
0 0 0 0
.75 0 0 0
. 18 adults from 56 larvae


0
0
0
8 adults


0 0
0 0
0 0
from 37 larvae


Series D, treated May 1-3, 1945


50 4
60 3
70 2
Check (untreated)


.75 0 0 0 0 0
0 0 0 0 0 0
.75 0 0 0 0 0
* . .* . 4 adults from 26 larvae






-29-


Discussion

To analyze the data better, the tests from tables 9 through 14
have been Pummarized in table 15. In these tables, the results from
larvae immediately removed from cocoons, and of those replaced in
storage, as given in tables 10, 12, 13, and 14, have been combined.
The combined data in tables 8 and 15 show that the first objective,
that of reducing the present dosages pt 60 and 70F., cannot be ful-
filled. It is true that under certain circumstances reduced schedules
were effective, but taken from the overall standpoint, a reduction
would not be advisable. The experimental tests were planned to dupli-
cate conditions often associated with nursery-stock fumigation, i.e.,
treatment at any date between January and May, replacement in nursery
storage after fumigation, the shipment of stock immediately following
fumigation, possible differences in resistance of lprvae in different
localities, and different storage conditions. Therefore a satisfac-
tory fumigation schedule should be one that produces complete mortality
under all of these conditions in experimental tests.

The same conclusion was reached by Armitage and Steinweden in
corroborating tests in California (see footnote, p.2). In series of
tests with hibernating lqrvee fumigated for 3 and 4 hours with 2 lb.
at 70, and 3 lb. at -OF., in December 1944, January, February, and,
March,1945, there were survivors with 3-hour exposures under both
60 and 70 schedules in February with larvae that had been in hiberna-
tion 7 1/2 weeks, and in a March test with 3 lb. for 3 hr. at 60 with
larvae that had been in hibernation for 9 weeks.

It is also shown that on the basis of available data, the second
objective, that of developing additional dosage schedules for lower
temperature levels, cannot be fulfilled. The two projected series of
dosage schedules, i.e., 4 lb. at 50F.; 6 lb. at 40; and 8 lb. at
30 (table 8); and 4 lb. at 50; 5 lb. at 40; Pnd 6 lb. at 32
(table 15) were both insufficient to produce complete mortality of
larvae under all the nursery-stock fumigation conditions tested. This
does not mean that such schedules cannot be developed, but rather that
the selected dosages were not high enough. Until further studies are
made, therefore, schedules for fumigation at 500, 400, and 32 cannot
be recommended.

:urth
(1) Tests with larvae from the two sources showed that those from
California consistently yielded slightly higher survival than those
fro YTei., Jersey. This could be interpreted to mean that larvae from
different localities or preas will not react exactly the snme. On the
other ',nd, it could mean that the differences in handling and rearing
methods wtre responsible.

(?) Hiberapting larvae held in cold storage at 32 to 38F. showed
less survival than those kept uaider simulated nursery-stock storage
conditions.









- 30 -


*


0




"4



"4
r4<
>4
0

I


I
I


0 00D CA11" 1 10 1 8 01













cm 0h M0


14

Cd
54
0






4)
(4

'r4


r4


0

0


4S


*








S 0
A
I 6

c4.4 A






L.. ..



6










1D to
40
D 0
E 4,
*









Ai t3
m





1* 6* -

oo
A <<'

*'44,
D O6






I 4,









0
t'

6 44


540 0



024

04


00000
0000
So r4o r4


*.*I 0 0
0CD 0M 0
r-4 0-4


cla
4,

S- 0 1 0 I 4)
10 COD M 1 0 10 I
9-4 v-4 0





to to to # 8 1 CA 1 84
r41 P4
It-
eS


to02 O C%) CM mt
F-4 0-4 i-r r-I


SS0

0p*0
W40
544
054
0
0 $4
64
5-4
30
"4^





0
1 i








42
E-4




f-.



4,
1 E:2
** **

4,
a

0
54
E4


0

$4
0


0
A4
C,


P8888
r-4 A A r4*< >



>4




(14 "0 9- 00
L'. 4 0 43 0 % 0 8
to
0
54
0






Sr4i CQ r to to
to t0 o 9 to) t>


x 9 1 !$1 1


-4 10 8
t0o Ob 4


0 0
M C C-o
9


100 88888
rr- 4 rf r-4V






- 31 -


(3) Larvae returned to simulated nursery-stock storage follow-
ing fumigation shoved a lower survival than those subjected to higher
temperatures following fumigation. These two conditions of post fumi-
gation handling are the same as those associated with the handling of
nursery stock, where some stock is fumigated and replaced in stock
piles or order bins, while other stock may be shipped soon after treat-
ment.

(4) Tests with larvae stored outdoors over winter were limited,
but the results compared favorably with tests made at approximately the
same date using larvae stored under controlled conditions, and indi-
cates that outdoor storage did not materially increase the resistance
of the larvae to fumigation.

(5) The previous evidence (table 7) that larvae became more
resistant as the season progressed was not substantiated in the 1944-45
tests (tables 10 through 14). Rather, the resistance appeared to be
about the same throughout the season.

(6) Of incidental interest was the fact that live adults were
found in check samples while still in simulated nursery-stock storage
beginning May 4. No adults emerged, however, from check samples as
long as they remained in cold storage.

TOLERANCE OF TFUITS TO METHYL BROMIDE FUMIGATION

Summer-Maturing Fruits Intended for Immediate Consumption

Tests were made as opportunity permitted to study the tolerance
of summer-maturing fruits. Fruits maturing in early or midsummer,
which moved directly to consumer markets were included in this classi-
fication. These may have been subjected to refrigeration, but were
not intended to be stored for winter marketing.

Samples of fruits were fumigated with dosages of 1 and 2 lb. at
700'., and 1.5 and 3 lb. at 60. Two schedules at each temperature
level were selected, since the final results of tests with eggs and
larvae were not known at the time the tests were made. Likewise, the
higher schedules helped to determine if a sufficient margin of toler-
ance existed. The condition of fumigated fruit was compared with that
of untreated checks at intervals following treatment.

A-oricots -The variety Royal (California origin)was used in tests
of July 12, 1944. This fruit was firm and well ripened. It was ob-
tained in the St. Louis fruit market, had been shipped under refrigera-
tion, and was in fruit storage at 601F. when purchased. After fumiga-
tion it was held at room temperature (850) for observation. There was
no evidence of injury, and all treated samples reacted similarly to the
check.






- 32-


Applej.--At St. Louis, the apples infested for mortality studies
were closely observed for symptoms of injury from the fumigation.
These included the varieties Wealthy, Black Twig, Lowland Raspberry,
Duchess, and Golden Delicious in all stages of maturity. No evidence
of injury was observed with dosage schedules ranging from 0.5 lb. at
80 to 2.5 lb. at 400F.

The State IEntomologists Office of Colorado kept records of ship-
ments into that State in 1942, when their oriental fruit moth regula-
tions were amended to allow apples to be received under fumigation
certificates. These records were supplied to the Bureau by courtesy
of F. H. Gates, State entomologist. A sample was removed at destina-
tion from each carload and kept under observation for effect of the
treatment on quality. No injury or decrease in quality was observed
in 21 carloads of early apples. These included some fumigated with
4-hour exposures as follows:

Number of cars OriTin Variety of apple Dosage schedule

13 Delaware Delicious 2 lb./4 hr. at 70.
Gano

3 Kansas --- 2 lb./4 hr. at 70

3 -do- -- 3 lb./4 hr. at 60

2 -do- --- 2 lb./2 hr. at 700

In other experimental studies by the Division of Control Investi-
gations, it has been shown that the variety Williams Early Red is sus-
ceptible to injury under certain circumstances. The same studies
showed no injury to Wealthy or Starr apples. It appears from these
observations that most varieties of summer apples can be fumigated
without risk of injury.

Cherries.--Local Montmorency cherries were purchased in June 1945,
and fumigated with dosages of 1.5 and 3 lb. at 600?., and 1 and 2 lb.
at 70 for 2-hour exposures. The cherries were well ripened and in
excellent condition, all with stems on. There was no evidence of in-
jury-, in fact, the treated samples maintained a higher percentage of
marketable cherries over a 2 weeks' period than did the checks, owing to
a greater amount of "nesting" in the check samples.

Nectarines.-The variety John Rivers (California origin) was pur-
chased in the St. Louis fruit market on July 12, 1944. It had been
shipped under refrigeration and was in fruit storage at 60*?. when pur-
chased. The fruit was firm and in excellent condition. After fumiga-
tion the samples were placed in room storage (85'?.) and compared daily
with untreated checks. There was no evidence of injury, and all treated
samples reacted similarly to the checks.






- 33 -


Par.-Bartlett pears (California origin) were purchased on the
St. Louis fruit market on August 9, 1944. These pears were firm but
well ripened. After fumigation internal injury showed in all pears,
being more severe with the heavier schedules. Typical injury is shown
in figure 2.

It was suspected that the maturity of the pears might have been a
contributing cause. Therefore additional Bartlett pears of California
origin were obtained, which were selected as being less mature than
the first purchase. These pears were in fruit storage at 600. when
obtained. The entire lot was warmed to 70. Two samples were fumiga-
ted with 1 and 2 lb. for 2 hr. as soon as they reached 70, Two more
samples were allowed to ripen at 70 for an additional 2 days, and a
third pair of samples were ripened for 4 days before treatment. The
results are given in table 16. They show that as the pears became more
mature, the amount of internal injury increased markedly.


Table 16.--Injury in Bartlett pears fumigated upon removal from
storage, and after 2 and 4 days' ripening at 7001. Fumigated
at 70 with 2-hour exposures


Ripening period after : Dosage Pears showing internal
removal from storage o : injury on 6th day 1/
Pounds Percent

0 1 7
2 0

2 1 60
2 87

4 1 100
2 100



I/Check samples shoved all pears sound on the 4th day, and
7 percent unmarketable on the 6th and 7th days.






-34-


Further tests were made with unrefrigerated pears of local origin.
These were of the varieties Kieffer and Garber, which at this season
were very green and hard. Samples of these were fumigated with the
same schedules used with the Bartlett pears. No evidence of injury
occurred even after several weeks of observation.

The evidence from these tests suggest that fully mature pears
may be susceptible to injury from methyl bromide.

Plumq.--The variety Duarte (California origin) was purchased in
the St. Louis fruit market on August 9, 1944. These plums had been
shipped under refrigeration and were in storage at 60F. when purchased.
They were firm and in excellent condition. After fumigation the sam-
ples were placed in room storage at 85 and compared daily with un-
treated checks. There was no evidence of injury, and all treated sam-
ples reacted similarly to the checks.

P!cht.!v-7ive lots of ripe peaches, variety unknown, of local
origin were fumigated in St. Louis in July and August 1943. No injury
was observed.

Fa.ll-maturing Fruits Intended for Cold Storage

In the development of fumigation schedules for the host fruits
of oriental fruit moth, it was necessary to consider the treatment of
late-m.turing fruits that normally are placed in storage for various
period,- before marketing, as well ae the treatment of summer-mBturing
fruits intended for immediate consumption. Apples are the principal
class of host fruit going into storage; therefore attention was con-
fined to them.

As shown in previous sections of this report, fumigation schedules
were developed for the treatment of fruit at temperatures as low as
40?-. The problem of the reaction of apples to such treatments remained
to be ied.

In 7-'':,ental work done by Phillips et al. k/ in Canada, the
*prl e ee injured unless they were stored for 6 weeks after picking
before tretraent.. Further tests by Phillips and Monro Z/ indicated a
v&m--etal differe-nce in tolerance. While most of these tests had been
md- tun..-- coc-ditions of vacuum fumig-ation, they indicated that the
problemm of "'niigating apples Immediately prior to storing, or after a
period of torrose, required thorough study.


6i/Fhilllps, We R., Monro, H. A. U., and Allen, C. E. Some obser-
vations on the fumigation of apples with methyl bromide. Sci. Agr. 19:
7-20, 1938.

/JPhillips, W. R.. and Monro. H. A. U. Methyl bromide injury to
apples. Jour. Econ. Ent. 32: 344-A45, 1939.






- 35 -


Testc were planned in 1943-44, to give evidence of the reaction
of apples fumigated before being placed in storage, as well as after
various periods of storage. As many varieties as could be obtained
were to be included to study varietal tolerance. The apples were to
be fumigated with a dosage schedule appropriate for the temperature
level existing at the time of treatment, as follows:

1.5 lb./2 hr. at 700F.
2 lb./2 hr. at 600
2.5 lb./2 hr. at 50
3 lb./2 hr. at 40

To provide information on the points listed above, four series
of tests were made at Louisiana, Mo.

Series A.--Apples were fumigated at packing-shed temperatures as
soon as picked. One half was placed in cold storage at 32 to 3801.,
and the other half at marketing temperatures of 40 to 55,

Series B.--Apples were held 2 weeks at packing-shed temperatures,
then fumigated. One half was placed in cold storage, and the other
half at marketing temperatures.

Series C.--Apples were held 1 month in cold storage, then fumi-
gated. at 400F. One half was replaced in cold storage, and the other
half was held at marketing temperatures.

Series D.--Apples were held 3 months in cold storage, then fumi-
gated at 400F. One half was replaced in cold storage, and the other
half was held at marketing temperatures.

It was not possible to obtain a sufficient quantity of all vari-
eties to carry them through the four series. Three varieties, Commerce,
Black Ben Davis, and Giant Geneton, were used in Series A and B only,
while small lots of Northern Spy, R. I. Greening, and Rambo were used
in series A only. The following varieties were used in all four series:

Black Twig King David Starking
Golden Delicious Red Delicious Staymen Winesap
Grimes Golden Red Winesap Willow Twig
Jonathan Rome Beauty York

In the varieties used in all four series, six bushel lots were
used, with one exception, divided as follows: one and one-half bushels
in each series, subdivided into one-half bushel for cold storage, one-
half bushel for marketing temperatures, one-fourth bushel for cold
storage check, and one-fourth bushel for marketing temperature check.

Pertinent data relative to these treatments are given in table 17.






- 36 -


Table 17.--Data relative to the treatment of apples in series A, B, 0,
and D, all exposures for 2 hours


Variety Date : Quantity' Date Apple
Variety tempera,: Do"age
picked. used fumigated. tempera- Do e
...... tuire
1943 Bushels 12943 Pond

Series A, treated at picking

Black Ben Davis 10/7 1 10/8 60 2
Black Twig 10/12 1.5 10/13 64-65 2
Commerce 10/7 1 10/8 60 2
Giant Geneton 10/7 1 10/8 60 2
Golden Delicious 9/25 1,5 9/26 46-48 2.5
Grimes Golden 9/18 1,5 9/19 58-62 2
Jonathan 9/17 1.5 9/18 58-60 2
King David 9/14 1.25 9/18 64-66 2
Northern Spy 9/25 1 9/26 46-48 2.5
R. I. Greening 9/25 0.25 9/26 46-48 2.5
Rambo 9/25 1 9/26 46-48 2.5
Red Delicious 10/2 1.5 10/3 62-63 2
Red Winesap 10/16 1.5 10/18 52-53 2.5
Rome Beauty 9/25 1.5 9/26 46-48 2.5
Starking 9/23 1.5 9/24 58 2
Staymen Winesap 10/2 1.5 10/3 62 2
Willow Twig 10/6 1.5 10/8 60 2
York 10/6 1,5 10/8 60 2
Series B, treated 2 week after picking

Black Ben Davis 10/7 1 10/23 56-58 2
Black Twig 10/12 1.5 10/26 53 2.5
Commerce 10/7 1 10/23 56-58 2
Gipnt Geneton 10/7 1 10/23 56-58 2
Golden Delicious 9/25 1.5 10/9 59 2
Grimes Golden 9/18 1,5 10/3 63 2
Jonathan 9/17 1.5 10/3 63 2
King David 9/14 1.25 9/30 63-64 2
Red Delicious 10/2 1.5 10/17 50 2.5
Red Winesap 10/16 1.5 11/1 56 2
Rome Beauty 9/25 1.5 10/9 59 2
Starking 9/23 1.5 10/9 59 2
Staymen Winesap 10/2 1.5 10/17 50 2.5
Willow Twig 10/6 1.5 10/23 56-58 2
York 10/6 1.5 10/23 56-58 2






- 37-


Table 17,--Continued


:, A o :..
Variety ae D :unt f Date : tempera- Dosage
Spiked used figated. tre


1943.


1943


Series C. treated after 1 month of cold storage

Black Twig 10/12 1.5 11/9 37
Golden Delicious 9/25 1.5 10/25 40
Grimes Golden 9/18 1.5 10/17 36-38
Jonathan 9/17 1.5 10/17 36-38
King David 9/14 1.25 10/14 36
Red Delicious 10/2 1.5 11/1 39
Red Winesap 10/16 1.5 11/16 36
Rome Beauty 9/25 1.5 10/25 38
Starking 9/23 1.5 10/24 36
Staymen Winesap 10/2 1.5 10/31 39
Willow Twig 10/6 1.5 11/7 36
York 10/6 .5 11/7


--I -


---I -


Series D,


Black Twig
Golden Delicious
Grimes Golden
Jonathan
King David
Red Delicious
Red Winesap
Rome Beauty
Starkirng
Staymen Winesap
Willow Twig
York


treated after 3 months of cold storage


10/12
9/25
9/18
9/17
9/14
10/2
10116
9/25
9/23
10/2
10/6
10/6


1.5
1.5
1.5
1.5
1.25
1.5
1,5
1.5
1.5
1.5
1.5
1.5
1.5


1/15/44
1 /
1/1
12/31
12%31


1/2
1/.15
l/1
1/I

1/2
1/2
1/2


39
38
38-4
36-40
36
37-38
38-39
38
38-41
37-38
38
38


LIBRARY
STATE PLANT BOAR1)


wv


vv






-38-


The samples held at marketing temperatures were examined at
approximately 10-day intervals until they were no longer of marketable
quality. Those in cold storage were examined at in'.ervpla thr(ughoat
the storage period.

No external nor internal injury was discovered on any variety in
series A, B, or D. External injury only was present o; two varieties
in series C, In Grimes Golden, 19 percent of the apples had from mild
to severe spotting of the skins (see figure 3) in the sample held at
marketing temperatures, but only 8 percent of those held in cold stor-
age. In Jonathan apples, 14 percent of those held under marketing
temperatures were spotted, while 5 percent of those in cold storage
showed injury (figure 4).

Evidence of injury showed up on apples held under marketing tempera-
tures earlier than on those returned to cold storage. Spotting was pres-
ent at the first observation of the former samples on the 9th day,. but
did not appear until the second examination of the cold-storage apples
on the 22nd day. In each case the injured area increased somewhat after
its first appearance.

Since no injury appeared in apples fumigated before cold storage,
and none appeared in apples fumigated after 3 months of cold storage,
further tests were confined to the periodical treatment of apples in the
earlier part of the cold storage period. These tests were made in the
1944-45 season.

The two apple varieties which showed injury in Series C of the
1943-44 tests, Grimes Golden and Jonathan, were selected for these tests,
with a third variety, Starking, which had shown no injury. Seventeen
bushels of each variety were placed in cold storage within a day after
picking. Samples were withdrawn from storage and fumigated at intervals
up to 17 or 18 weeks. On each date two samples of each variety were
fumigated, one with 2 lb./2 hr. at 400F. and one with 2 lb./4 hr. at 400.
The two dosage schedules were used in order to better delimit the margin
of tolerance. Each sample was divided after fumigation, one half being
returned to cold storage, the other half being placed at room tempera-
tures of 55 to 75, Check samples were handled and divided similarly.

The results are presented in table 18. It is evident that the
apples under the conditions of these tests were more susceptible to in-
jury during the first few weeks of storage. In each instance the sus-
ceptibility appeared to reach a peak after the start of the storage period,
then recele until no injury occurred after the 5th or 6th week. As would
be. expected, more apples showed injury with the 4-hour exposures than with
the 2-hour. Also, apples held at room temperature following fumigation
showed more injury than those returned to cold storage, in fact, Jonathan
and Starking showed no injury to apples fumigated for 2 hours and returned
to cold storage. As was the case in 1943-44 tests, injury became apparent
on the apples held at room temperature before it did on those returned to
cold storage,






- 39 -


4MC-4 H lO o 0c
V)1 tO tI- M r- I
I


I0
I


I 0
I


f-4 co to cc C
r-4 v-4


0
6)

0
42

eO *
r-4 w
0 'V
0

0
f-I





Sr4c
0 -
54 .,4




0
V-4 ft

$4



0 0

0 O

".4
54
0 5
00



84


54Dl

*u4.
5z 4
0
6l)0
*r 0
|4
$4
00
r 434






0cc









0 0




6)0
I












')4


0
6) v


tf-
6B











E-4


.r4
A4
0
54












0}










4P
ca


.0











0
M4
CM


44%

0
E-4
f -f









4J
0









0
E-1






-4>
E41
*3



















0




0
(0.. ..

































'-4

4P
a :


















0

















E-1


6S
4'
0)


54


a.. ..
I I
I 5


0)




0 *"
b -f
0 ..a




E4

*****
ICt
.fIt


I 0
1


1 0
1


0 0000


I I 10 I I
I m) 1 0 t


w0Cm 0000 0 0


I 0
I


I 0

0p


io oo00000o


I


I0
I


0o t0Oo00o0ooo


I 0


t0
I


I C
I


I 0
I


I 0
I
I


I 0


I0


I 0 L'n O











0 Coo
4)
S
I
4'>10 CtO 0
0




10000






(0

M O









v to to n


I0


I0


CQto t~ 0020toutQ Io |I to I Cu-
tf it V) U) t4 tI I p






or-4 v OwOc- mo I--I C-4 CIO
f-4 r-4 r-4 F-4 f-4


00 CV o 0





' ,-4 -4 mC1






0 r4- OC m .0


0oC1 -
LO I0 <


m to 0 0


54
0
.0
CQ


J3

0
.0


I
I


If-. gC~~ ec~
IC~~ I~ I~ I


.rq I*-



.0







II54
0
t4 0
0 .,


$o$:p- 04 44 $< 1 S I VC


,, i ,9 M c1 IOI





- 39a -


000 10
1


- B

00






" I


0














41.
4)
U2*










pg
41
0*
0I


$4

0
1-4




Id






0
E-4



.. 0.
*@V



c
1-4






4>
0
E-4

0





$4
0
CH


S4
V
0
'-4
.. ..










Ile






m
4)>
0





'-4

r*-4




-V.
1*-4

p4
41*
4)
0V



fi-

0
Sf4


(4

~4O


I C
I


Io


0I
I


10
I


; Coll- 1 i I 1 X I


I0


1 i4 1 1 I i


0000


S0000


0000


LO to C- CO Oa


IC,
I


I;


I0


I0
I


l's



to
1


10
1


I oI t0
It1I lw


0,-4 M D
r-4 r-4 r -4 p4Ir-


I


!o
I


I0


000 Jo 0
I


** **

*


0 0
.0


0000


I 0
I


vo

0 4)
o(
(P 0


j0


- 0.- *. ..


** **







Pract: I' all ap-.iB .a9:- eventually cut to determine the
presence r i.e of i e:'a. "nJury. No instances of internal in-
Jury were f-.i any t -at.


Tests ,
ported by -
eties of a
storage at
2 lb. at 4+
in one T,
storage.


1, la alifornia to parallel those in St. Louis were re-
c t,, and S airpwedea (see footnote p.2). In three vari-
3- fearmain, aoae Beauty, and Vinesap-removed from cold
J 7 or biweekly intervals and fumigated with a dosage of
I or axposeure of 2 and 4 hours, slight injury appeared
!.'3L Bea ty, aftar no storage and after two weeks'


.Jacussion


It ap,
fruits int,
bromide at
out much .
the fumigat
do age ach.
storage mi.-
difference i
ently from
gating app ,

If fu"
to fumigate
in cold et,.
leos than a


-a 'x the terts reported here that most summer-maturing
Sfor immecia-e consumption can be fumigated with methyl
.-se proposed f.,r oriental fruit moth control, with-
S-Jury. M-. .u-e pears showed evidence of injury, but
1 of LY c rl,,r.l of pears in California with comparable
e ould s)gg-'st the period of shipment to market and
q e een an influncing factor. Apples show a varietal
't;tion. -ad also a single variety will react differ-
: ': year. COution should be used, therefore, in fumi-
:i' test Piamples treated first.

a rg apple are to be fumigated, it would appear best
iore ,tIr:g hem in cold storage, or after 2 months
A '.mlgati. of apples which have been in cold storage
s 'houle be avoided unless trial tests are first made.

SUMM/5RT


Cooper :v, tests were made at St. Louis, Mo., in 1944-46 by the
Bureau of *m Ira and Plant QCarantine, and the California State
Department of A,:rculture, to study the fumigation of fresh-fruit
hosts of th r o tal frvit moth, the possible revision of fumigation
schedules f, i ry-stcr host, and the tolerance of host fruits
to methyl by-. .'tmigat ior

Minim:. ?tikation dose schedules causing complete mortality of
artificial] Lnieeted apples were 0.75 lb. of methyl bromide per 1,000
cubic feet io ? hours at 800, 700, and 600F., and 1 lb. at 500 and 40.

Minim.u .-ioage schedules causing complete mortality of naturally
infested fr-It iere 1 lb. at 700, and 1.25 lb. at 600 and 50'.

Minimum= lopage schedules causing complete mortality of oriental
fruit moth eggs were 1.5 lb. at 70, 2 lb. at 600, and 2.5 lb. at 50.






- 41 -


A satisfactory series of sc-hedules for fresh fruit was proposed
as follows

1 lb./2 hr. at 800.
1.5 lb./2 hr. at 700
2 lb./2 hr. at 60
2.5 lb./2 hr. at 50
3 lb./2 hr. at 40

Almost complete mortality of oriental fruit moth larvae embedded
in fruit was caused by cold storage for 2 1/2 months or more. Although
the danger of dissemination of this pest by fruit subjected to cold
storage for any considerable length of time would be slight, it was
indicated that a cold-4storage treatment as a basis of certification
under oriental fruit moth quarantines would not be entirely acceptable.

The results of tests with hibernating larvae showed that when all
conditions under which nursery stock is fumigated were considered, no
reduction could be made in the present fumigation schedules for nursery
stock of 2 lb./4 hr. at 7007., and 3 lb./4 hr. at 600.

It was also shown that on the basis of available data, additional
scnedules for the fumigation of nursery stock at temperature levels
below 60F. could not be recommended. Two projected dosage curves,
i.e. 4 lb. at 500; 6 lb. at 400; 8 lb. at 30; and 4 lb. at 500; 5 lb.
at 400; 6 lb. at 30, did not cause complete mortality of hibernating
larvae. Further studies with increased dosage curves will be neces-
sary to accomplish this purpose.

These studies also indicated that hibernating larvae from differ-
ent localities will show a different degree of resistance to fumiga-
tion, as California larvae showed slightly more survival than those
from New Jersey. Hibernating larvae stored in cold storage showed
less survival than those stored in simulated nursery-stock storage.
Larvae returned to simulated nursery-stock storage after treatment had
less survival than those removed to room temperature for observation.
Larvae stored outdoors were not appreciably more resistant to fumiga-
tion than those stored otherwise. The resistance of larvae to fumiga-
tion as the season progressed did not appear to change materially.

The summer-maturing fruits tested were found to be tolerant to
methyl bromide fumigation with the exception of mature pears. Green
pears were uninjured. Apples were found to have a varietal toler-
ance.

Ten varieties of fall-maturing apples fumigatted in 1943 immedi-
ately after picking, 2 weeks after. picking, and after 1 month and






42 -

3 months in cold storage showed no evidence of injury. Two additional
varieties showed injury vhen fumigated after 1 month of cold storage.
In further tests in 1944, three varieties placed in storage the day
following picking showed injury when fumigated at weekly intervals
through the first 6 end 6 weeks. No injury occurred to apples fumi-
gated after 7 to 18 weeks of cold storage.

































/


-v


o tiO 0 I
LI O'- 't I

113HN31 HVJ


nO 0
ro ro


5331930


0 10
oM -


,-I
0
ir\





0
0




cd9
0




0Q)









.'o
C
I0)






01)
4.,



9C.0







r-i
r- 0
bo







0 )



H





.r-t
0)
0)

H
0)2


.00,














ii.
I


#2'I


IWO"



-41--


A "


"- -',


a J


1%


k'V


4'*9^



A:,


Figure 2.--Internal injury in ripe Bartlett pears caused by fumigation
with methyl bromide.













IVY


- "


6 V


Figure 3.--Sxtern)l Injury on Grimes Golden spple, c!rsed by fumigation
with methyl bromide, after 1 month in cold storage.


: i .
< Aa























-o.












Figure 4.---F~xternAl injury on Jonnthrn npnolep eqused by tumigathnm
with met bride, fter month in cold storage.
--: ^ ',,'^




















Figure 4.-SEyternal injury on Jonnthe~n np )lea caused by fuclg.ation
with methyl bromide, .oftpr i month in cold storage.




UNIVERSITY OF FLORIDA

3I 1262 09239I 1 I845III II
3 1262 09239 1845