SELECTING MACHINERY AND EQUIPMENT 



337 



The body of the duster, including hopper and fan, may be 

 of light but durable material, as an alloy of aluminum. The 

 hopper should be airtight to hold the dust which sifts through 

 very small openings. Its capacity should be at least 100 

 pounds, equivalent to considerably more liquid spray, to avoid 

 frequent stops for refilling. The opening for pouring the dust 

 materials from the sacks into the hopper should be large 

 enough to make the transfer easy. The machine should have a 

 force feed to insure continuous and uniform delivery, with stiff 

 revolving brushes inside the hopper to pulverize any small 

 lumps and to work the material from the hopper through the 

 openings into the air chamber. Machines are now being 

 equipped with self-mixers to mix the dusts just prior to ap- 

 plication. 



The fan should be 16 inches in diameter with about six 

 blades, making 3500 or more revolutions per minute. 



A feed control lever, regulating the amount of material 

 passing from the discharge pipe, should be located so that the 

 operator may reach it conveniently. The lower section of the 

 discharge pipe attached to the feed channel should be of rein- 

 forced rubber to provide flexibility in moving the pipe. For 

 high trees a third section of pipe should be available. A dis- 

 charge pipe 4 inches in diameter is standard. 



Engines of 8 to 14 horsepower, depending on the size of 

 the outfit, are required. 



Traction dusters are used chiefly for field crops; hand 

 dusters are very convenient for home gardens. 



(r) Consider the Advisability of a Stationary Spray Plant. 

 Stationary spray plants are in use in the Pacific Coast states, 

 the Shenandoah-Cumberland region of the South, New Jersey, 

 Ohio and Canada in orchards varying in size from 5 to 300 

 acres. Developed primarily to handle spraying problems on 

 irrigated lands or on areas that, owing to special conditions, 

 could not be sprayed at the proper time in the usual manner, 

 they have steadily increased in number and have made a place 

 for themselves in American fruit growing. 



