1941] 
SERVICE AND REGULATORY ANNOUNCEMENTS 
27 
circulated by means of a fan or blower throughout the entire 4-hour fumigation 
period. 
(5) The use of a fumigation chamber, lined with sheet metal throughout 
and with a metal-covered door closing against gaskets and held tightly in 
place by refrigerator door fasteners, is recommended. 
I'e) Fumigation treatment under partial vacuum. — (1) Fumigation under a 
partial vacuum equivalent to at least 24.5 inches of mercury must be done 
with a dosage of 4 pounds of methyl bromide per 1.000 cubic feet of chamber 
space, including the space occupied by the commodity, with an exposure of 1% 
hours, the vacuum to be maintained throughout the entire period. 
(2) The temperature of the soil balls shall be 75° F. or above, and the 
diameter of the soil balls shall be not greater than 11 inches if spherical, or 
thicker than 11 inches if not spherical. 
(3) The fumigant-air mixture shall be circulated in the fumigation chamber 
by means of a fan the first 15 minutes of the exposure period to mix the 
vaporized fum'gant thoroughly with the air in the chamber and bring it in 
to; tact with the surface of the soil balls. The soil balls shall be washed with 
one or more changes of air at the end of the exposure period. 
(4) A standard vacuum fumigation chamber which can be closed tight and 
will withstand an external pressure of at least one atmosphere is required. A 
vacuum pump of sufficient capacity to reduce the pressure within the vacuum 
chamber to the equivalent of 3 inches of mercury (a 27-inch vacuum at sea 
level) in not more than 20 minutes is necessary. 
(d) Disclaimer. — In authorizing the movement of potted plants or nursery 
stock fumigated according to the requirements stated above, it is understood 
that no liability shall attach either to the United States D3partment of Agri- 
culture or to any of its employees in the event of injury resulting from the 
use of the fumigant. 
(e) Caution. — Methyl bromide is a gas at ordinary temperatures. It is 
colorless and practically odorless in concentrations used for fumigation of 
plants. It is a poison, and the operator should use an approved gas mask when 
exposed to the gas at concentrations used in fumigation. The plants in -the 
fumigation chamber should be well aerated by blowing air through them and 
the room adequately ventilated before it is entered. 
This circular supersedes all instructions set forth in circular B. E. P. Q. 486 
dated January 28, 1939. 
Avery S. Hoyt, 
Acting Chief. 
[Filed with the Division of the Federal Register March 21, 1941, 11 : 37 a. m. ; 
6 F. R., 1572.] 
B. E. P. Q. 489, revised. March 21, 1941. 
TITLE 7— AGRICULTURE 
Chapter III — Bureau of Entomology and Plant Quarantine 
Part 301 — Domestic Quarantine Notices 
white-fringed beetle regulations modified 
§ 301.72-5a Administrative instructions modifying wh it e -fringed beetle quaran- 
tine regulations authorizing treatment of potting soil. Introductory note. 
Further experimental work by the Bureau of Entomology and Plant Quarantine 
of the United States Department of Agriculture indicates that complete mortality 
of the various stages of the white-fringed beetles (Pantomorua leucoloma Boh. 
and P. peregrinus Buch.), in potting soil, can be obtained by fumigating the soil 
at a dosage of 2 pounds of carbon disulphide per cubic yard. The instructions 
in Circular B. E. P. Q. 48'.), issued on January 28, 1039, which authorized treat- 
ment of potting soil either by fumigation with methyl bromide or by heating, 
as a prerequisite to certification are herein extended to provide thai carbon 
disulphide fumigation may also be employed as a method of treatment of potting 
soil for control of the white-fringed beetles. The specifications for the two treat- 
ments formerly authorized are brought forward unchanged in the instructions 
which follow and this circular supersedes all instructions set forth in Circular 
B. E. P. Q. 48') dated January 28 1939. 
(a) Treatments authorized. — Pursuant to the authority conferred upon the 
Chief of the Bureau of Entomology and Plant Quarantine by subsection (a) of 
