12 PLANT QUARANTINE AND CONTROL ADMINISTRATION [Jan.-Mar. 
P. Q. C. A.— 329. 
ADMINISTRATIVE INSTRUCTIONS 
Sterilization of Grapefruit and Oranges by Heat Under the Mexican 
Fruit-Worm Quarantine 
(Approved March 3, 1932; effective March 5, 1932) 
The revised Mexican fruit-worm quarantine regulations, effective March 5, 
1932, in paragraph (c) of regulation 6, make certain sterilization requirements 
necessary with respect to the interstate shipment of host fruits which have been 
produced in the regulated area and which are to be shipped to certain Southern 
and Western States. 
Under the provisions of that regulation, the following method of sterilizing 
grapefruit and oranges by heat is authorized : 
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 eight hours. 
No specifications as to the exact methods and equipment for obtaining these 
conditions are prescribed. Available information clearly indicates that by the 
application of dry heat the required temperatures can not be reached 
without injury to the fruit. To prevent such injury it is necessary to main- 
tain a very high humidity throughout the period of treatment. In the tests 
where successful performance was obtained, live steam as the source of heat 
was applied in such a way as to secure as nearly as possible a uniform distri- 
bution of steam-heated air so directed as not to discharge directly on the fruit. 
The air temperature ranged from 110° to 112° F. and the air was very moist. 
The fruit was held in field boxes stacked four boxes high and without special 
means of separating the boxes in each stack. The experiments indicate that 
the fruit should be sterilized after coloring, if this is necessary, and before 
packing for shipment, and then cooled down to a temperature around 45° as 
soon as possible after sterilizing. Wax or paraffin, either dry or in solution, 
should not be applied to this fruit either before or after sterilization. 
Such treatment is authorized in sterilization plants in the regulated area 
approved by the Plant Quarantine and Control Administration. The adminis- 
tration will approve only those plants which are adequately equipped to handle 
and sterilize the fruit. Such sterilization will be done under the supervision 
of representatives of the administration. These inspectors should at all times 
be given access to fruit while in process of sterilization. They will supervise 
the movement of the fruit from the car to and from the sterilizing rooms. 
Sterilization is not being considered as a means of authorizing movement of 
infested fruit. All infested fruit will be promptly destroyed. The requirement 
of sterilization, therefore, applies to areas believed to be entirely free from 
the pest with the object of eliminating any residual risk, even after intensive 
inspection. 
While the results of the experiments so far conducted have been successful, it 
should be emphasized that inexactness and carelessness in operation may 
result in injury to fruit. In authorizing the movement of fruit sterilized in 
accordance with the above requirements, it is to be understood that the depart- 
ment does not assume responsibility for fruit injury. 
Lee A. Strong. 
Chief, Plant Quarantine and Control Administration. 
[Thesp administrative instructions "vere sent to all common carriers doin? business in or 
through the State of Texas.] 
P. Q. C. A.— 330. 
ADMINISTRATIVE INSTRUCTIONS 
Sterilization of Grapefruit and Oranges by Refrigeration Authorized 
(Approved March 3, 1932; effective March 5, 1932) 
The revised Mexican fruit-worm quarantine regulations, effective March 5, 
1932, in paragraph (c) of regulation 6, make certain sterilization requirements 
necessary with respect to interstate shipment of host fruits which have been 
produced in the regulated area and which are to be shipped to certain Southern 
and Western States. Under the provisions of that regulation, the following 
method of sterilizing grapefruit and oranges by refrigeration is hereby 
authorized : 
