16 ANNUAL REPORTS OF DEPARTMENT OF AGRN OLTURE, 19-19 
aroma or I aste of tobacco. These si adies should be coni inued on tobacco 
grown in different environments. 
The results of both Investigations indicate that, with the exception 
of the off-taste caused by nil dosages of benzene hexachloride, I 
insect icides xn ill not injure the tobacco when used under pracl icaJ field 
condil inns. Whether I hey will ever accumulate in injurious quant it ies 
in the -oil as tin' result of normal insecticide application- to to! 
foliage is unknown at present. 
New Fumiganl for Cigarette Beetle in Stored Tobacco 
A new fumiganl containing equal parts of acrylonitrile and carbon 
tetrachloride has given better control of the cigarette beetle in closed 
tobacco >torai:.'- under commercial fumigation conditions than the 
hydrogen cyanide now commonly employed by the industry. At dos- 
oi 2 to l' 1 - pounds per LOCK) cubic feet, this new material killed 
cigarette beet les to a greater depth in the tobacco containers than did 
the hydrogen cyanide. It was successfully used in cigarette, Turkish, 
and various type- of cigar tobaccos without injurious eff( 
Control of Aphids on Potatoes Improved 
Experiments wore conducted in Maine to determine the most I 
nomica] form of DDT insecticide- for the control of aphids on pota- 
toes. Du-ts and suspensions protected the crops Longer than emul- 
sions, and dusts impregnated with oil were more effective than dusts 
in which the oil had been mixed with the DDT by mechanical means. 
Reduct ion in the spread of leafroll disease following DDT spray treat- 
ment- for the control of aphids was demonstrated for the first time. 
Tozaphene spray injured t he foliage of Katahdin potatoes and did not 
give satisfactory control of aphids. 
In the Yakima Valley of Washington tetraethyl pyrophosphate was 
shown to he effective against aphids on potatoes when it was applied 
a- a dust by airplane. This was found to he one of the best methods 
of killing these aphids after the plants had become large enough to 
meet bet ween t he rows. 
DDT Gives Best Residua] Action on Pea Aphid 
In experiments in Wisconsin, Washington, and Oregon, DDT dusts 
gave a- good immediate control of the pea aphid a- those containing 
parathion, rotenone, or tetraethyl pyrophosphate, and in residual 
action were far superior to the other materials. The residual action 
of parathion did not extend beyond approximately l" days. Because 
of the residue on pea idnes, however, DDT should not he used when 
the vines are t" be i\'d to milk cows or animals being finished for 
slaughter. 
New Insecticides Effective igainsl ipbids on Cole Crops 
The turnip aphid was controlled with parathion dust at Strengths 
.1 l<>\\ .1- 0.26 percent and the cabbage aphid at 0.5 t<> l percent, in 
