Vegetable Plant Lice 



15 



To get the pressure, deliver the liquid and cover the vines re- 

 quires modification of even the engine-equipped sprayers. The num- 

 ber of rows usually covered must be reduced. The holes in the noz- 

 zle disks must be reamed out and the side, and possibly the center 

 nozzles, may have to be reset. 



Fig. 10 



Field Sprayer in Operation 



To work out the modifications necessary, the following plan may 

 be followed : ( 1 ) fill the tank with water, start the engine, with ac- 

 cess to nozzles cut off, set the pressure valve at 250 pounds as indi- 

 cated by the gauge, and then open the nozzles and spray a short 

 round; (2) if the pressure does not keep up to 250, cut off one or 

 more of the units for the outer rows until the pressure holds 250 

 pounds; (3) then spray a measured fraction of an acre, determining 

 exactly how much water is used; (4) if the amount of water deliv- 

 ered is less than 100 gallons per acre, slightly enlarge the delivering 

 holes through the nozzle plates and repeat the trial spraying; (5) if 

 the pressure is not maintained it may be necessary to cut off another 

 row unit ; if the pressure is right but the amount of water delivered 

 is below par, the nozzle holes will have to be further enlarged, but if 

 the pressure is low and the amount of water delivered insufficient, 

 bring up the pressure first ; (6) thus continue to manipulate pressure 

 and delivery until you get 100 or more gallons per acre at a pressure 

 of approximately 250 pounds, (7) adjust the overhead nozzle at 



