34 MISC. PUB. 526, U. S. DEPT. OF AGRICULTURE 



should be practically free from chloride and contain not less than 

 51 percent of the cyanogen radical. The chemical may be purchased 

 in the form of "eggs", each weighing y 2 or 1 ounce. Dosages may, 

 therefore, be easily calculated by counting the number of eggs required. 



Hydrocyanic acid gas is used as a fumigant to control such pests 

 as scale insects, aphids, whiteflies, mealybugs, and thrips on plants 

 and bulbs in fumigation vaults, greenhouses, or tents. The dosages 

 range from y 8 to 1 ounce of sodium cyanide per 1,000 cubic feet of 

 space, with exposure periods of 1 to 5 hours or overnight. The dosage 

 and length of exposure depend upon the plants' tolerance to the gas. 

 Plant tissue of all kinds is very susceptible to the action of this gas, 

 and the margin of safety between dosages which will kill the insect 

 and the plant is very narrow. The materials are generally combined 

 in the proportion of 1 ounce of sodium cyanide, iy 2 fluid ounces of 

 sulfuric acid, and 3 fluid ounces of water. 



Plant materials are fumigated in darkness and afterward protected 

 for a short period from light to avoid plant injury. 



In certain instances growing plants may be fumigated under canvas 

 tents placed over them. For example, the boxwood leaf miner may 

 be controlled by this method, sodium cyanide being used at the rate of 

 2 ounces per 100 cubic feet of space, with 3 fluid ounces of sulfuric acid 

 and 6 ounces of water, for a period of 1 hour. The plants must be 

 dormant and dry, and the temperature must not be too high — usually 

 40° to 55° F. 



Caution. — In carrying out a fumigation a definite procedure and 

 certain precautions must be followed. Sodium cyanide should, 

 therefore, be used only by experienced f umigators thoroughly fa- 

 miliar with the methods of handling it and the hazards involved. 



Hydrocyanic acid gas is colorless and is one of the most deadly 

 poisonous gases known. In case of accidental inhalation of the 

 gas, the person affected should be kept in the open air and not 

 allowed to exert himself. Inhalation of ammonia vapor may be 

 of some help. 



All forms of cyanide are extremely poisonous and should be 

 plainly labeled and kept in a safe place. To avoid deterioration, 

 store the material in tight containers. 



SODIUM FLUORIDE 



Sodium fluoride (NaF) is a white, very poisonous powder, soluble 

 in water. The commercial product and commonly employed grade of 

 powder is 94 to 97 percent pure. 



Sodium fluoride, undiluted, when dusted in the areas frequented by 

 ants and roaches, except the Surinam roach, will gradually eliminate 

 them. Sodium fluoride should not be used on plants. 



Caution — Since sodium fluoride is poisonous if taken inter- 

 nally, it should be kept in tight containers plainly marked 

 "Poison" and stored in a dry, safe place away from foods. If the 

 dust is inhaled, it is somewhat irritating to the respiratory 

 passages. 



In New York City all sodium fluoride must be colored blue, and the 

 National Association of Insecticide and Disinfectant Manufacturers, 

 Inc., has gone on record favoring this practice throughout the United 

 States. This coloring is done to denote its poisonous nature. 



