16 MISC. PUB. 526, 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 1gallon of spray 100 gallons of spray 
A Wel 0/2) Cs) 6 eae at i a at eee 4 tablespoonfuls. 6 quarts. 
2 PeCTCCNi = ee. Loses Ses 8 tablespoonfuls. 8 gallons. 
5 percent. #224) 2 ets ee ee 1 ceuptnuls: 7% gallons. 
LO percents eee ea 215 cupfuls. 15 gallons. 
Kerosene at the rate of 1 or 2 quarts per 100 gallons is sometimes 
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. 
Nye 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, PoHAsO,). 
The other, generally called “basic lead arsenate,” is discussed on page 
17. Both are fine powders and are 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.O;). 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. 
