96 



MISC. PUBLICATION 6 2 6, U. S. DEPT. OF AGRICULTURE 



preparing the lead arsenate solution as 

 directed above and then adding IK 

 teaspoonfuls of 40-percent nicotine sul- 

 fate to each gallon of the lead arsenate 

 mixture, without soap. 



A spray combining a fungicide, a 

 stomach poison, and a contact insecti- 

 cide may be made by first preparing a 

 gallon of bordeaux mixture (p. 97) and 

 then adding to this 3 level tablespoon- 

 fuls of lead arsenate and 1% teaspoon- 

 fuls if 40-percent nicotine sulfate. 



One drawback to the use of lead 

 arsenate is its tendency to leave a 

 whitish residue on the sprayed leaves. 

 This should not be stressed as a de- 

 cided objection, however, since spraying- 

 is recommended only when the plants 

 are seriously affected or threatened 

 and the material must be applied 

 promptly. Following an effective treat- 

 ment and the disappearance of the 

 defoliators, the new leaves which appear 

 as the plants grow will show neither 

 spray residue nor insect injury. 



Caution. — All arsenical compounds, 

 including lead arsenate, calcium ar- 

 senate, and paris green, are poisonous 

 to man and higher animals and should 

 be clearly labeled "POISON." They 

 should be kept away from food products, 

 and stored in a place inaccessible to 

 children and animals. The arsenicals, 

 except paris green, are usually colored 

 pink to denote their poisonous nature. 



Lead Arsenate as a Dust 



A dust prepared as follows is useful 

 in controlling many leaf-chewing insects 

 and is easy to mix and apply: 



Powdered lead arsenate, 1 ounce, or part by weight. 

 Hydrated or air-slaked lime, talc, tobacco dust, or 



kaolin, 4^> ounces, or parts by weight. 

 Dusting sulfur, 4.}i ounces, or parts by weight. 



The ingredients are first thoroughly 

 mixed and then sifted several times 

 through a fine-mesh screen or ordinary 

 flour sifter. To apply this dust, use 

 any of the hand dusters or blower guns 

 available on the market. 



One-half ounce of 40-percent nicotine 

 sulfate added to the dust at the time of 

 mixing gives it contact-insecticidal prop- 

 erties. 



Where sulfur is being used as a fungi- 

 cide, or if red spiders, plant bugs, leaf- 

 hoppers, or thrips are infesting the 

 plants along with leaf-chewing insects, 

 lead arsenate may be added to the 

 sulfur and applied as a dust, as indi- 

 cated in the following formula: 



Dusting sulfur, 9 ounces, or parts by weight. 

 Lead arsenate, 1 ounce, or part by weight. 



Caution. — See "Caution "under Lead 

 Arsenate as a Spray, page 96. 



Calcium Arsenate 



Calcium arsenate is sold in powdered 

 form and is used for the control of chew- 

 ing insects in much the same manner as 

 lead arsenate. Calcium arsenate, how- 

 ever, is more likely to injure tender 

 plants because it contains more soluble 

 arsenic; consequently lead arsenate is 

 more generally used on flowering plants 

 and shrubs. The addition of three or 

 four times as much hydrated lime, by 

 weight, as calcium arsenate will make 

 it safer to use. The usual strength is 



2 to 3 pounds of calcium arsenate in 

 100 gallons of water. For small quan- 

 tities use 2 level tablespoonfuls of cal- 

 cium arsenate and 4 or 5 of hydrated 

 lime to each gallon of water. 



When calcium arsenate is used as a 

 dust, it should first be mixed with from 



3 to 4 times its weight of hydrated lime. 



Caution. — See "Caution" under 

 Lead Arsenate as a Spray, page 96. 



Paris Green 



Paris green is not being as widely used 

 for spraying as formerly because of its 

 tendency to burn tender foliage and 

 flowers. It is more generally employed 

 in the preparation of poisoned baits to 

 control cutworms, armyworms, grass- 

 hoppers, ants, sowbugs, and millipedes, 

 as discussed under the heading "Treat- 

 ment" for each of these pests. 



One ounce of paris green added to 

 3 gallons of water in which 2 pounds of 

 brown sugar has been dissolved makes 

 an effective spray against certain spe- 

 cies of thrips, especially the gladiolus 

 thrips, even though it may cause some 

 foliage injury. This spray should not 

 be used to control thrips except when 

 it is impossible to obtain tartar emetic 

 (p. 45), which is as efficient and does 

 not cause burning. 



When paris green is used against 

 chewing insects, the spray is prepared by 

 adding 2 level teaspoonfuls of paris 

 green and 3 or 4 level tablespoonfuls of 

 hydrated lime to 1 gallon of water. The 

 addition of hydrated lime decreases 

 the possibility of burning the plants. 



Since paris green settles quickly, it is 

 necessary to keep the spray solution 

 constantly agitated while spraying. It 

 should not be combined with sprays 

 containing lime-sulfur, soap, sulfides, 

 or any fungicide containing ammonium. 



Caution. — See "Caution" under 

 Lead Arsenate as a Spray, page 96. 

 Paris green should not be inhaled. The 

 skin, and especially open wounds, 

 should be protected from this com- 

 pound, or serious poisoning may result. 



