The ultra low volume sprayer is the least tested to date and its 

 use is limited by relatively few pesticide formulations which can 

 be used. This type of sprayer has greater usage potential in the 

 future when pesticides may be delivered directly from their pack- 

 aged container to the tree without benefit of water as a carrier. 



The low volume sprayers in general use in many parts of the 

 world are powered by the "power- take-off " on the tractor used to 

 pull them through the orchard but also may be engine operated. 

 They offer several advantages over the conventional sprayer: 



1. Many of these machines cost less to purchase than conventional 

 machines since most have smaller tanks, low pressure pumps 

 and no motor. 



2. They often are less costly to operate and maintain since 

 fuel consumption is less with only the tractor motor being 

 used in the spraying operation. Their simple design and 

 low pressure pump which wears at a much slower rate also 

 contributes to their low maintenance. 



3. Spraying with these machines requires less total time 

 because more time is spent applying sprays to the trees 

 and less time in filling the spray tank and weighing out 

 chemicals. As much as 50°6 savings in spray time can be 

 realized with a change from 400 to 20 gallons per acre. 



4. Reductions by 80-6 in the amount of water used has resulted 

 in a significant savings on farms v/here water is scarce 



or must be transported for some distance. This reduction 

 in the amount of spray mixture used also eliminates the 

 need for a "nurse tanker" and operator often used in high 

 volume spraying. 



5. Low volume spraying generally requires about 20-40% less 

 pesticide per acre than high volume spraying. 



Factors Affecting Spray Deposits 



Since the mass of air generated by airblast sprayers is the 

 major source of energy dispensed in carrying spray droplets to all 

 parts of the tree, some understanding of its character and factors 

 affecting it should be helpful in deciding the type of sprayer to 

 purchase. The airblast is generated by various types of fans and 

 may vary in volume and velocity depending on the particular design 

 or type. Droplets are either injected into the airstream through 

 nozzles which aid in forming droplets into a range of sizes from 

 30 to 600 microns (1.0 micron (mu) is equal to 1/25,000 inch or 

 0.001 mm), or the liquid is released into the airstream under low 

 pressure and is broken or sheared into droplets. This shearing 

 action is typical of the high velocity low volume sprayers commonly 

 referred to as mist-type sprayers. 



