32 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1953 
Synergists for Allethrin Evaluated 
Twenty-three piperonylamidee previously found to sliow synergism, 
when combined with pyrethrinfl were evaluated in combination with 
allethrin. Twelve 01 these sprays produced house fly mortalities 
three or more times greater than expected on the basis of equivalents. 
They appear to be worthwhile allethrin synergists. 
Aerosol Formulas Licensed 
One hundred and forty-five aerosol formulas were submitted by 
industry for approval under the aerosol public service patent license. 
Of these, 121 were approved. The remainder were inferior to the 
tentative oflicial test aerosol, or were chemically unsatisfactory. The 
commercially produced synthetic thiocyanate, Thanite, was permitted 
in household aerosols for the first time in 1952. This followed clear- 
ance on toxicologic^] hazards by the Food and Drug Administration 
after entomological tests by Bureau personnel. 
Parathion Purification Process Patented 
A public service patent was obtained by two Bureau chemists for 
a process for purification of parathion. 
Three Manufacturers Now Producing Bureau-Synthesized 
Insecticide 
Allethrin, first synthesized by Bureau chemists in 1949, is now being 
manufactured commercially by three companies, having a total po- 
tential production capacity of 600,000 pounds per year. The United 
States Army has purchased large quantities of aerosols and other 
insecticides containing allethrin and it is also being used extensively 
in household aerosols. 
Crops Analyzed for Insecticide Residues 
Residues resulting from the experimental application to apples and 
peaches of dieldrin sprays for plum curculio control were determined 
at the Bureau's laboratory at Vincennes, Ind. Isolated plots were 
sprayed between April 8 and May 22, three sprays being applied 
to apples and live to peaches. All sprays were at the rate of 1 pound 
of 50 percent dieldrin per LOO gallons. Samples were collected and 
analyzed at intervals from the time of the final -piay until harvest. 
No residue was detected on the peaches at harvest. Less than 0.1 
p. p. in. of organic chlorine was found on the apples at that time. 
A ho :it Vincennes an experiment was performed in which corn 
plant- iii various stages of growth were treated with DDT wettable- 
powder or emulsion sprays ml wo applications of L.5 pounds of DDT 
per acre. Analyses were made of the corn kernels from these plants 
to determine whether any DDT might have been translocated within 
the plant and stored in the kernels because of their relatively high 
oil content. The results showed that there was no DDT either on 
the surface of the kernels <>r within them. 
Re [dues from commercial and experimental treatments <>f shade- 
grown tobacco at Quincy, Ma., were analyzed at Vincennes, These 
