8 MffiS-C. PUB. 52 6, U. S. DEPT. OF AGRICULTURE 



be prepared, the former at 1 pound per gallon, the latter at ll/ 2 

 pounds per gallon. These must be stored in tightly covered earthen- 

 ware, wood, or glass containers. Equal quantities (the lime suspen- 

 sion being well mixed before the measured volume is removed) of 

 these preparations can then be diluted, each to one-half the volume 

 desired, and mixed to form bordeaux mixture. One gallon of fin- 

 ished mixture will require 1% cupf uls of each preparation ; 3 gallons, 

 1 quart of each. 



Caution. — Bordeaux mixture may cause gastric disturbances if 

 taken internally. All unused portions should be disposed of or 

 covered so that they will be inaccessible to children and animals. 

 It is also somewhat irritative to the eyes and skin. 



CALCIUM ARSENATE 



There are several compounds which may correctly be called calcium 

 arsenate. The marketed product, unlike lead arsenate, is not a single 

 chemical compound but a complex mixture of several arsenates and 

 an excess of lime, whose proportions vary considerably between brands 

 and even between different lots of the same brand. However, it usually 

 contains the equivalent of from 40 to 42 percent of arsenic pentoxide. 

 Calcium arsenate absorbs carbon dioxide slowly from the atmosphere 

 during storage and increases its content of water-soluble arsenic oxide, 

 unless it is packed in containers that are practically airtight. This 

 change, however, is relatively unimportant. 



The domestic manufactured calcium arsenate is a white powder, 

 but when sold as an insecticide it is usually colored pink for the purpose 

 of marking it as a poison. It is used as a spray at the rate of iy 2 to 3 

 pounds per 100 gallons of water, in much the same manner as lead 

 arsenate (p. 16), but it is more generally employed as a dust. As a 

 dust it is used principally and in immense quantities in the undiluted 

 form on cotton to control the boll weevil. Likewise in the undiluted 

 form as a dust it is one of the best controls for the tomato f ruitworm. 

 Calcium arsenate is sometimes used for the control of cabbage "worms," 

 the Mexican bean beetle, Colorado potato beetle, pepper weevil, codling 

 moth, apple maggot, grape rootworm, grape berry moth, and cherry 

 fruitfly, and to a limited extent on flowering plants. Applications 

 on peppers and cotton may result in heavy aphid infestations. It is 

 more likely to injure foliage than is lead arsenate, but it is less ob- 

 jectionable from a residue standpoint because of the absence of lead. 

 It is less effective than lead arsenate against the codling moth. Since 

 it is likely to cause foliage injury, three or four times its weight of 

 hyclrated lime is often added to render it safer to use. 



Caution. — Like all arsenical compounds, calcium arsenate is 

 very poisonous to man and higher animals, and should be clearly 

 labeled and stored away from any food products. It should not 

 be applied to the edible parts of fruits and vegetables unless a 

 long period intervenes before harvest or unless acid washes are 

 used to remove the arsenical. 



CALCIUM CYANIDE 



Calcium cyanide (Ca(CN) 2 ) reacts with moisture in the air and 

 gives off the deadly poisonous hydrocyanic acid gas that is toxic to 



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