LIBRARY 
 
 July 1*6 «59 
 
 United States Department of Agriculture 
 
 Agricultural Research Administration 
 
 Bureau of Entomology and Plant Quarantine 
 
 A SHALL FIELD DUSTER 
 
 George 7. Johnson, 
 Division of Truck Crop and Garden Insect Investigations 
 
 A duster was constructed for treating individual tomato plants in 
 field plots at Columbus, Ohio, in connection with experiments for the 
 control of the tomato fruitworm (Heliothis armigera (Hbn.)). Weighed 
 quantities of dust ranging from 2 to 7 gm. were used in the duster de- 
 scribed here. 
 
 Description 
 
 A cutaway diagram of the duster is shown in figure 1. The dust 
 chamber (Aj was formed from the bulb part of a 50-ml, pipette. The 
 constricted top part of the bulb was cut off. About an inch of the bottom 
 stem was retained, and was bent and shaped to form a dust-discharge ori- 
 fice (Bj approximately 0.08 inch in diameter. The air tube (Cj was made 
 from a 7-inch length of l/8-inch copper tubing. The outlet (D) of this 
 tube was constricted to approximately 0.08 inch by sealing the end with 
 solder and boring a hole through the seal. 
 
 The dust chamber and the air tube were placed in a protective hous- 
 ing made from a cylindrical piece of wood about 2j inches in diameter and 
 6 inches long. A hole to fit the dust chamber was bored into the cylinder 
 deep enough to sink the top of the dust chamber about 3/M- inch below the 
 top of the wood cylinder. The top 3/k inch of the cylinder was cut to 
 make a funnel-shaped opening. The bottom was hollowed out roughly as in- 
 dicated. A 3/lo-inch hole for the air tube was bored in the wood cylinder 
 so as to bring the air tube into proper alignment with the dust-discharge 
 orifice (B). 
 
 The dust chamber was fastened in place with plastic cement around 
 the top and bottom. The position of the tip of the air tube (D) to give 
 the best dusting action was determined by trial. The air tube was fas- 
 tened in place with plastic cement. 
 
 Operation 
 
 A 2-cylinder air compressor of the paint-sprayer type T powered by a 
 small gasoline engine, supplied the air for dusting. An air line with a 
 cut-off valve connected the compressor with the air tube of the duster. A 
 weighed quantity of dust was placed in the dust chamber. When the air was 
 
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 turned on, the air stream across the tip of the dust chamber delivered the 
 dust from the chamber. This duster has "been operated with the compressor 
 set at pressures of 10 to 17 pounds per square inch. 
 
 Figure 1. — Cutaway diagram of duster,