INSECTICIDES AND EQUIPMENT FOR CONTROLLING INSECTS 45 



The barrel pump. — This type of sprayer has a hand-operated pump 



attached to a barrel or similar container for the spray. The assembled 

 outfit is mounted on a sled or wheels (fig. 5) or loaded in a wagon 

 or truck. In certain types, called wheelbarrow sprayers, the container 

 is small enough so that it is mounted between handles with a single 

 wheel in front and is pushed by the operator. 



Figure 5. 



-Barrel pump mounted on wheels and equipped with hose, extension 

 rod, shut-off. and nozzle. 



Depending upon the size of the outfit, the barrel sprayer is fairly 

 satisfactory for spraying commercial plantings of truck, fruit, nurs- 

 ery, or other crops. However, the operation of the pump is laborious, 

 and it is difficult to maintain constant high pressure. Because of these 

 facts a power outfit is to be preferred. 



Traction sprayers. — This type of sprayer is usually mounted on two 

 wheels. Essentially it consists of a tank, with a pump geared to the 

 wheels and with the nozzles usually attached to a fixed boom (fig. 6). 

 Ordinarily these machines are horse-drawn. Pressures reaching as 

 high as 125 to 250 pounds per square inch can be maintained, provided 

 that the rig is in constant motion. 



Machines of this type were designed for spraying field crops, includ- 

 ing potatoes and tomatoes and small fruits, where it is not necessary 

 to make any stops, as is the case when spraying trees. For the most 

 part traction sprayers have been replaced by power machines, the 

 latter being much more satisfactory. 



Power sprayers. — These machine- arc so called because the pumps 

 are driven by motors, either gasoline or electric. They range in size 

 from small 10- to 50-gallon tank-capacity outfits, with single-cylinder 

 pumps which maintain a pressure of 150 to 200 pounds, to large rigs 



