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: Nicotine Dust for Truck-Crop Insects. 17 
The pea aphis is considerably larger than most other aphids and 
is more resistant to insecticides. In both liquid spraying and dust- 
ing a higher strength of nicotine is required for effectiveness than 
is ordinarily used. Not less than a 6 per cent strength of dust 
should be used, while many growers prefer 10 per cent. Several 
large seed companies in California have used the 10 per cent 
strength on their sweet peas for three seasons, and are much better 
satisfied with the results than with any previous control work with 
liquid sprays. 
All types of dusters employed were used with success on peas. 
For a hand duster, the fan type is very satisfactory, as the con- 
Fic. 6.—Hand-operated fan duster in use against the pea aphis. 
tinuous flow of dust permits the operator to make the application 
at a steady walk, holding the discharge pipe directly over the row 
(Fig. 6; Fig. 14, at left). It may use a little more dust than the 
bellows type, but will cover the acreage much more rapidly, at 
least 1 acre more a day. 
One-horse dusters in operation in a pea field are shown in Figures 
7, 8, and 9. Under average conditions a machine of this type will 
cover about 1 acre an hour. A power outfit with a single discharge 
hose used successfully in plots of sweet peas is shown in Figure 10. 
Until the peas are large it is better to use the discharge. pipes similar 
to those in Figures 12 and 13. Such outfits are used by several 
