1938] SERVICE AND REGULATORY ANNOUNCEMENTS 53 
potatoes moving to points outside the regulated areas between June 15 and 
October 15 via refrigerator car when such treatment is carried out under the 
supervision of an inspector and in a manner satisfactory to him. 
TREATMENT METHOD 
Fumigation of potatoes in dry refrigerator cars with methyl bromide at a 
dosage of 2 pounds per 1,000 cubic feet of space, including the space occupied 
by the potatoes and bunkers of the cars, for a period of 2 hours during which 
time the car shall remain tightly closed with the plugs in place in the ventilator 
hatches. The temperature within the car when fumigated shall be not less 
than 70° F. Provision shall be made for circulating the mixture of air and 
fumigant in the car for as long a time as is deemed necessary by the inspector. 
At the end of the fumigation period the hatches shall be opened, the plugs 
removed, screens placed in the hatch openings, and the car shipped under 
standard ventilation. 
In authorizing the movement of potatoes fumigated according to the require- 
ments stated above, it is to be understood that no liability shall attach either 
to the United States Department of Agriculture or to any of its employees in 
the event of injury. 
Caution : Methyl bromide is a gas at ordinary temperatures. It is colorless 
and practically odorless in concentration used for the fumigation of potatoes. 
It is a poison, and the operator should use an approved gas mask when exposed 
to the gas at concentrations used in fumigation, and when opening the hatches 
for ventilating the cars. The car should not be entered until it is well aerated. 
Avery S. Hoyt, 
Acting Chief, Bureau of Entomology and Plant Quarantine. 
ANNOUNCEMENT RELATING TO MEXICAN FRUITFLY QUARANTINE 
(NO. 64) 
April 8, 193S. 
B. E. P. Q. 472 (Superseding P. Q. C. A. 329). 
ADMINISTRATIVE INSTRUCTIONS— STERILIZATION OF GRAPEFRUIT AND ORANGES 
BY HEAT UNDER THE MEXICAN FRUITFLY QUARANTINE 
[Approved April 5, 1938 ; effective April 8, 1938] 
INTRODUCTORY NOTE 
Investigations in sterilizing fruit for the Mexican fruitfly have shown that 
the holding period at 110° F. can be reduced from 8 to 6 hours provided the 
time for heating the fruit to this temperature is at least 8 hours, making a min- 
imum treating period of 14 hours. In order that shippers may take advantage of 
this reduction, the administrative instructions issued as circular P. Q. C. A. 329 
on March 3, 1932, are modified and superseded by the following instructions. 
Under the authority contained in paragraph (e) of regulation 6 of the Mexi- 
can fruitfly quarantine regulations, as revised effective October 15, 1937. and 
having determined that shipments of unsterilized oranges and grapefruit from 
infested areas might involve risk of spread of the Mexican fruitfly, notice is 
hereby given that sterilization is required as a condition of issuance of permits 
for the interstate movement of oranges and grapefruit produced in areas desig- 
nated by the Chief of the Bureau of Entomology and Plant Quarantine as in- 
fested. Such sterilization shall be in accordance with one of the following 
prescribed treatments : 
(1) Heating the fruit to a temperature of 110° F. or above (not to exceed 
112°) in the approximate center of the fruit and holding the temperature of 
110° or above (not to exceed 112°) for a period of 8 hours; 
(2) Heating the fruit for a period of not less than 14 hours during which 
time the fruit shall be raised to a temperature of 110° F. at the approximate 
