1934] SERVICE AND REGULATORY ANNOUNCEMENTS 
therefore recommended that treatment be applied only when the plants are 
dormant or semidormant. 
Temperature. — The water must be maintained at a temperature of 112° F. for 
the entire period of treatment. If the temperature falls below 111.5° the infes- 
tation may not be destroyed; if it rises above 112.5° the plants may be injured. 
Period of treatment. — The treatment must be continued for 70 minutes after the 
root masses are heated throughout to 112° F. 
Preparation for treatment. — Before being tendered for treatment, plants shall 
have all excess soil removed and the roots pruned. Large clumps should be 
divided as much as possible without injuring the roots. 
Small plants and root stocks may be packed loosely in wire baskets or in other 
containers providing water can circulate through the masses. Large plants must 
be placed individually in the water. 
Before the plants are immersed, thermometers must be inserted with the mer- 
cury bulbs in the center of at least three of the largest clumps, baskets, or root 
masses, and placed at each end of the tank and in the center. In addition, three 
thermometers, with the mercury bulbs in the water, must be placed in the same 
relative positions as the thermometers in the root masses. 
Application. — The roots must be immersed completely. Temperature readings 
should be recorded on form no. 91. These temperatures should be taken at each 
end of the tank and in the center with individual thermometers. 
Care of plants after treatment. — The treatment by hot water is complete when 
the plants are removed from the tank. The way plants are handled after treat- 
ment may seriously affect subsequent growth. Tubers should be dry when packed 
for shipment. Plants should be cooled slowly to room temperatures. Plants 
should not be removed from the hot water and heeled in cold soil. Pot the plants, 
or set them in the ground as soon as possible after cooling to room temperature. 
They should be protected against reinfestation. 
C. Carbon disulphide dip 
Material. — Use 50 percent miscible carbon disulphide. Fully described in 
1, C. 3. 
Caution. — Observe the precautions mentioned in 1, A. 1. 
Equipment. — Metal or wooden tanks or tubs in which the plants can be treated 
at a temperature of 70° F. should be provided. 
Condition of plants. — Dilute carbon disulphide emulsion is least injurious to 
roots when they are dormant or semidormant. Treatment should be applied during 
the dormant period of the variety to be treated. 
Temperature. — 'The temperature of the dilute emulsion must be maintained at 
approximately 70° F. If the temperature falls below 65° the treatment may not 
be effective; if it rises above 70° the plants may be injured. 
Dosage. — Miscible carbon disulphide (50 percent) must be mixed with water at 
the rate of 45 cubic centimeters to 10 gallons. 
Period of treatment. — The roots must be immersed for 24 hours. 
Preparation of treating bath. — Determine the capacity of the container and use 
45 cubic centimeters of miscible carbon disulphide for each 10 gallons of water. 
There are 231 cubic inches in a gallon. Pour into tank and stir until mixed, which 
operation should be done just before using. Do not mix with a mechanical agitator 
or stir too violently. 
Preparation of plants. — This treatment is not effective when the soil about the 
roots is too wet or when the diameter of the soil ball is more than 6 inches. The 
temperature of the plants should be at least 60° F. at the beginning of the treat- 
ment. 
Application. — The roots must be immersed completely. 
Care of plants after treatment. — The treatment is complete when the plants are 
removed from the solution. The suggestions regarding handling of plants after 
treatment with hot water should be followed. Plants should be protected from 
reinfestation. 
D. Carbon disulphide emulsion, field treatment 
The basis of certification of field nursery plants treated with miscible carbon 
disulphide shall be: (1) That the concentrated stock solution shall be freshly 
mixed carbon disulphide and castor-oil soap in the proper concentration. (2) That 
all five conditions, subsequently mentioned, governing the application of the 
treatment have been met. 
Material. — Use 50 percent miscible carbon disulphide. (See 1, C. 3.) 
