LIBRARY STATE PLANT BOARD UNITED STATES DEPARTMENT 07 A(HI CULTURE Bureau of Entomology and Plant Quarantine Washington, D. C. E.S.P.Q.— kj2. April S, I93S. Sup e r sedi ng P QCA- - 3 29 . ADlvII HIS TRAT I VE INSTRUCTIONS STERILIZATION 07 GRAPSiRUIT AND ORANGES BY HEAT UNDER THE MEXICAN ERUITFLY QUARANTINE (Approved April 3, 193S; effective April ?, 193c) INTRODUCTORY NOTE Investigations in sterilizing fruit for the Mexican fruit fly have shown that the holding period at 110° P. can be reduced from 8 to o hours provided the time for nesting the fruit to this temperature is at least 3 hours, making a minimum treating period o^ lU hours. In order that shippers may take advantage of this reduction, the administrative instructions issued as circular PQCA-J29 on March 3» 193<-» are modified and superseded "by the following instructions. Under the authority contained in paragraph (e) of regulation 6 of the Mexican fruit fly quarantine regulations, as revised effective October 15? 1937 » and having determined that shipments of unsterilizec! oranges and grape- fruit from infested areas might involve' risk of spread of the Mexican fruit- fly, 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 designated by the Chief of the Bureau of Entomology and Plant Quarantine as infested. Siacn st " riii zation shall be in accordance with one of the following prescribed treatments: (1) Heating the fruit to a temperature of 110° 7. or above (not to exceed 112 ) in the approximate center of the fruit and holding the tempera- ture of 110° or above (not to exceed 1'J 2° ) for a period of 3 hours; (2) Heating the fruit for a period of not less than l't hours during which time the fruit shall be raised to a temperature of 110° 7. at the ap- proximate center of the fruit and shall bo maintained at or above that tem- perature for the last fa hours of such treatment. 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 cannot be reached without injury to the fruit. To prevent such injury it is necessary to main- tain a very high humidity throughout tie 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 t<, discharge directly on the fru -2- Tiie air temperature ranged from 110 to 112 F. and the air was very noist . The fruit was held in field boxes stacked four boxes high and without' special means cf separating the "boxes in each stack. The experiments in- dicate that the fruit should he sterilized after coloring, if this is necessary, and before packing for shipment, and then cooled down to a tem- perature around F. as scon as possible after sterilizing. Wax or par- affine, either dr: 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 which are approved by the Bureau of Entomology and Plant Quarantine. The Bureau will approve only those plants which arc adequately equipped to handle and sterilize the fruit. Such sterilization will be done under the supervision of inspectors of the Bureau. 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. While the results of the experiments so far conducted have been suc- cessful, 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 under- stood that the Department does not accept responsibility for fruit injury. AJSRI S. HOYT , Acting Chief, Bureau of Entomology and Pl^nt Quarantin e .