16 MISC. PUB. 52 6, U. S. DEPT. OF AGRICULTURE 



To dilute the stock emulsion to the desired strength for spraying, 

 the following quantities should be used : 



Strength of Emulsion to make Emulsion to make 



spray desired 1 gallon of .spray 100 gallons of spray 



1 percent 4 tablespoonfuls. 6 quarts. 



2 percent 8 tablespoonfuls. 3 gallons. 



5 percent—- 1% cupfuls. 7% gallons. 



10 percent 2y 5 cupfuls. 15 gallons. 



Kerosene alone at the rate of 1 or 2 quarts per 100 gallons is some- 

 times used with lead arsenate for control of the codling moth. For 

 this purpose it may be emulsified in the tank with bordeaux mixture, 

 with some of the proprietary spreaders, or with the milder soaps. 

 When used in this manner it acts primarily as an adhesive or deposit 

 builder. 



LEAD ARSENATE (ACID) 



There are several chemically different compounds known as lead 

 arsenate. Two of these are commonly used as insecticides. The one 

 usually sold is "acid lead arsenate" (di-lead ortho arsenate, PbHAsO t ) . 

 The other, generally called "basic lead arsenate," is discussed on page 

 17. Lead arsenate is a fine powder and is readily kept in suspension 

 in a spray. The residue tends to adhere strongly to foliage. 



Acid lead arsenate should contain the equivalent of not less than 

 31 percent of arsenic pentoxide (As 2 5 ). It should not contain more 

 water-soluble arsenic than the equivalent of 0.5 percent of arsenic 

 pentoxide. 



Lead arsenate is manufactured in this country as a white powder, 

 but since 1938 it and other white arsenicals have been colored pink 

 when marketed as insecticides. This material is not quite so toxic to 

 insects as is paris green but is much safer to apply on plant foliage. 

 It is used both as a spray and as a dust, with a suitable carrier. Its 

 most popular use is for control of the codling moth, plum curculio, 

 apple maggot, pear slug, grape berry moth, and many other chewing 

 insects attacking fruits. It is also used for many insects on flowers, 

 trees, and shrubs, such as bagworms, beetles, weevils, and grasshop- 

 pers, and for the control of the Colorado potato beetle, beet webworm, 

 and tomato hornworm. It also finds extensive use in treating soil to 

 control Japanese beetle and Asiatic garden beetle larvae and related 

 soil-infesting forms. 



Lead arsenate is ordinarily used at dosages ranging from 2 pounds 

 to 8 pounds per 100 gallons of spray. It may be used with other insec- 

 ticides, such as nicotine and oil emulsion, or with fungicides like lime- 

 sulfur, sulfur, and bordeaux mixture. It should not be used with 

 sodium sulfide or potassium sulfide, or with most soap sprays. It 

 should not be used on any vegetable crop where the portion treated is 

 to be subsequently used for food, nor on fruits after the fruit has 

 formed, except in instances where the interval before harvest is suffi- 

 ciently long to permit the poison to be weathered off or where the resi- 

 dues will be removed at harvest by acid or alkaline washes. In some 

 localities materials such as a weak bordeaux mixture or zinc sulfate 

 and lime must be added to lead arsenate sprays to avoid injury to 

 foliage. On beans this insecticide often causes plant injury and 

 reduction in yield. 



