58 BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE [Apr.-Juue 
(/) Methyl bromide. — The commercial grade is required. Containers of 
methyl bromide should be stored in a cool, well-ventilated place. Avoid leakage 
by seeing that the valves on the cylinders are tightly closed. 
Methyl bromide is a gas at ordinary temperatures. As it has only a very 
slight odor, toxic concentrations of methyl bromide may be encountered and the 
persons so exposed may be unaware of the danger. While methyl bromide is not 
so toxic as hydrocyanic acid, it is dangerous to inhale the gas or to get the 
liquid in contact with the skin. Rubber gloves should be worn while releasing 
the liquid methyl bromide either from cylinders or applicators. Caution. — 
Rubber gloves absorb methyl bromide which may result in skin injury if they 
are worn continuously. 
(g) Naphthalene. — Flake naphthalene, free from tar, is required. Naphtha- 
lene is not explosive and it burns only with difficulty. It is advisable, however, 
to keep the material in the solid and gaseous form away from fire. 
Long exposure to naphthalene may cause giddiness and headache. When 
these symptoms develop, the individual should get into the open air. 
(h) ParadiehloroJ)enzene. — A technical or C. P. grade of small- to medium- 
size crystals is required. 
Paradichlorobenzene burns only with difficulty. It is advisable, however, to 
keep the material from fire. Long exposure to the gas may cause giddiness and 
headache. When these symptoms develop, the individual should get into the 
open air. 
Treatment of Soil in Absence of Plants 
(0 potting soil 
Potting soil must be treated by the use of heat, carbon disulfide, naphthalene, 
or lead arsenate. 
Fumigated or heat-treated soils should be aerated to remove excessive 
fumigant or heat before using for potting plants. When stored, the soil must 
be kept and handled in such a manner as to prevent reinfestation. When 
stored for a long time, without aeration, it is advisable to thoroughly mix the 
upper and lower layers in the bin. When used as recommended, these treat- 
ments do not impair the fertility of the soil. 
Lead arsenate treatments are more limited in their application because of 
the susceptibility of some nursery plants to arsenical poisoning. E-418 of the 
Bureau of Entomology and Plant Quarantine gives some information on the 
susceptibility of nursery plants to lead arsenate in the soil. 
(J) Heat treatment 
Condition and type of soil. — Soil of any type may be treated, provided it is 
friable. 
Temperature. — The soil must be heated throughout to 130° F. 
Period of treatment. — The temperature of the soil must be maintained at 
130° F. for 30 minutes. 
(2) Carbon disulfide fumigation 
Equipment. — A gastight bin or box is required. It is necessary to have the 
top, sides, and bottom tight. 
Condition and type of soil. — Soil of any type may be fumigated, provided it 
is friable and thrown loosely into the bin or box. Wet soil must never be 
fumigated. 
Temperature. — The temperature must be at least 45° F. when the fumigant 
is applied and must not fall below 40° during the course of the treatment. 
Dosage. — One pound (352 cubic centimeters) to 1 cubic yard. 
Application. — One method is to apply the fumigant while the soil is being 
put into the bin or box. Place 18 inches of soil in the bin or box. Inject 
carbon disulfide at the rate of 176 cubic centimeters for each square yard of 
surface, distributing the material uniformly in holes 2 inches deep and 18 
inches apart, using 44 cubic centimeters to each hole. Fill the holes with soil 
immediately after the liquid is injected. When the first 18 inches of soil have 
been treated, put in 18 inches more and repeat the operation. This can be 
repeated until the container is filled. 
