SELECTING MACHINERY AND EQUIPMENT 327 



At low pressures the gun of the usual type will give poor 

 results, and many growers have made a mistake in attempting 

 to use two guns on an outfit that could carry but one. The 

 usual type of sprayer of 3V2 to 4 horsepower will not carry two 

 guns of the present types and do a uniformly good job of spray- 

 ing. This is because the guns, when operating fully, require 

 more material than the pump can deliver. Studies indicate 

 that under such conditions the guns will take 4 to 5 gallons 

 each per minute while the rated capacity of the pump is only 

 8 to 10 gallons per minute, in practice often falling below this. 



Table 41 gives the results of actual orchard tests made by 

 the Virginia Agricultural Experiment Station* with various 

 types of equipment at different pressures. The nozzles listed 

 were arranged in sets of three or four. Note (a) that Vs-inch 

 spray disk openings are too large to give satisfactory results 

 at any pressure used, and (6) that the nozzles arranged in a 

 straight line gave as great a delivery of material and fully as 

 great a drive of material as the guns. 



Modifications of the spray gun under different names are 

 now available, claiming greater perfection in adjustment and 

 manipulation. 



10. Spray Rod, Some growers still prefer the spray rod 

 (Fig. 118) . One or more nozzles are mounted at the end. Both 

 bamboo and iron rods are in use, but the former is much lighter, 

 of greater diameter, and easier to hold. It is hard work to 

 manipulate a spray rod all day, so that these factors are of 

 considerable importance. 



An aluminum or brass core extends through the rod, carry- 

 ing the spray material to the nozzle. The fittings holding the 

 rod in place must be kept tight or the rod will turn in the 

 hands independent of the core. Cracks or checks in the rod 

 should be wound with tape as soon as they appear. A collar 

 of metal or rubber at the upper end serves as a shield or guard 

 to prevent the drip from working back along the rod to the 



* W. S. Hough, Va, Agr, Exp, Sta. Bull 260, 1928. 



