1934] SERVICE AND REGULATORY ANNOUNCEMENTS 
5 
Dosage. — Lead arsenate must be applied at the rate of 1,500 pounds to each 
acre, or 35 pounds to each 1,000 square feet. For subsequent re- treatments, 
lead arsenate must be applied in sufficient quantity to restore the original con- 
centration of 1,500 pounds of the insecticide per acre. The quantity to be added 
in the re-treatment will be determined by analyses. 
Application. — The lead arsenate may be applied with a suitable distributor 
or broadcast by hand. The lead arsenate must be thoroughly mixed and incor- 
porated with the upper 3 inches of soil. 
Period of treatment. — As lead arsenate is a stomach poison which has to be 
eaten by the larvae, it may take several weeks before all the infestation is elim- 
inated. " Do not plant, heel in, or plunge plants in soil thus treated until after 
October 1. 
Safety zone. — In addition to the area desired to be certified, there shall be 
treated a 3-foot strip of land around the entire plot, coldframe, hotbed, etc. 
No plants may be certified from this strip. In the case of coldframes, hotbeds, 
etc., extending into the ground to a depth of 12 inches or more, thus preventing 
larval movement into the frame, no such safety zone is required. 
Marking. — Nurserymen shall be required to furnish suitable stakes at least 
4 inches square and at least 30 inches long to be placed on the boundaries of 
certified plots. Proper designations will be stenciled on the stakes by the 
Department. In the case of coldframes, hotbeds, etc., having fixed bounda- 
ries, proper designation will be made on such coldframes, hotbeds, etc., and no 
stakes will be required. 
C. 2. Fumigation with carbon disulphide 
Material. — A technical, U.S. P., or CP. grade of carbon disulphide should be 
used. Carbon disulphide is explosive. Observe the precautions mentioned in 
1, A. 1. 
Equipment. — A tarpaulin or other gasproof cover must be provided to cover 
the soil after fumigation. 
Condition of soil. — Soil of any type may be treated providing it is friable. 
Wet soil must not be treated. 
Temperature. — The temperature of the soil 6 inches below the surface must be 
at least 45° F. when the fumigation is applied. If the temperature falls below 
40° before the fumigation is complete, the treatment must be repeated. 
Weather conditions. — The ideal conditions for fumigation are a warm, humid 
atmosphere without wind. 
Season. — The fumigation must not be applied when adult beetles are present. 
An exception may be made in the case of plots that are protected from beetles. 
Dosage. — Carbon disulphide must be used at the rate of 6 pounds, or 2,100 
cubic centimeters, to 100 square feet of soil surface. 
Application. — Carbon disulphide must be uniformly distributed over the 
surface of the soil. Apply it in holes 12 inches apart and 1 to 2 inches deep, 
putting 21 cubic centimeters in each hole. Fill each hole with soil immediately 
after the liquid is poured in. Complete the fumigation as quickly as possible, 
covering each section with tarpaulin as soon as it is fumigated. 
Period of fumigation. — The soil must remain covered for at least 48 hours. 
Safety zone. — Same as that prescribed in 1, C. 1. 
Marking. — Same as that prescribed in 1, C. 1. 
C. 3. Treatment with carbon disulphide emulsion 
Material. — Carbon disulphide emulsion consists of a dilution of the stock 
solution known as "50 percent miscible carbon disulphide." The stock solution 
is composed of equal parts of carbon disulphide and castor-oil soap emulsifier. 
The castor-oil soap emulsifier must be prepared according to the directions pub- 
lished in the Journal of Industrial and Engineering Chemistrv, volume 20, pages 
849-850, August 1928. 
The component materials, carbon disulphide and castor-oil soap emulsion, are 
supplied in separate containers — the carbon disulphide in one container and the 
emulsified castor-oil soap in another. Equal parts of each by volume must be 
used in preparing the stock solution or miscible carbon disulphide. The stock 
solution when diluted with water forms carbon disulphide emulsion. 
The miscible carbon disulphide should be prepared in the field as it is used. 
It should not be prepared in quantity before use. 
Caution. — Miscible carbon disulphide and carbon disulphide emulsion are in- 
flammable. Observe the precautions mentioned in 1, A. 1. 
