THE CONTROL OF INJURIOUS INSECTS 381 



spray but is very liable to clog. A needle operated by a spring can be 

 used to clean the clogged nozzle. It is unsuited to large orchards or 

 with large outfits. "Buena," "Cyclone," "Eureka," "Dewey," 

 " Spramotor, " "Vapor Mist" are trade names. 



The Disk nozzle, known under several trade names, has been evolved 

 from the Vermorel for modern power outfits. It is larger and has 

 a disk plate at the orifice which may be changed when desired. The 

 chamber is broad and flat and the liquid enters it by two spiral grooves. 

 As a result a strong rotary motion is given to the liquid which breaks 

 up into a fine spray as it leaves the large opening. It is the most satis- 

 factory nozzle at the present time. Trade names are "Friend," "Cy- 

 clone," "Jumbo," "Atomic," "Mistry," "Power," "Simplex," 

 "Tiger," "Whirlpool." 



The "Nusystem" or "Spra-gun" Nozzle is an improved form of the 

 Disk. It has a large chamber, entered by several spiral grooves, at one 

 end of a heavy brass rod, and an adjuster at the other end. Near this 

 end is an opening for attachment to the hose (Fig. 247). 



COST OF SPRAYING 



The cost of spraying depends on: (i) the materials used, (2) the 

 location and size of the trees, (3) the outfit and (4) the rate of pay for 

 labor. 



Many carefully kept records are now available for comparison, 

 but the following cases will suffice here: 



Case I. — Cost of spraying 500 20-year-old apple trees in Okanagan 

 Valley, B. C, averaged 8 cents per tree. 



Case 2. — In Dr. Hedrick's experimental lo-acre orchard, Geneva, 

 N. Y., about 30 years old, the cost of spraying averaged per year for 

 10 years 41.8 cents per tree for 2-3 sprayings. 



Ca^e 3. — Five-year average cost of spraying eight orchards in Indiana, 

 the trees being from 18 to 23 years of age, a first dormant spray with 

 lime-sulphur, and four other summer sprays mostly with lime-sulphur 

 and arsenate of lead; 41 cents per tree, $16.89 per acre, and 17.98 

 gal. per tree (Bull. 194, Purdue Univ. Agr. Exp. Stn., 1916). 



Case 4. — Cost of spraying in New Hampshire (labor and material, 

 arsenate of lead and Bordeaux) ii3'^ cents per tree per application. 



Case 5. — In 19 16 the average cost of spraying eleven widely 

 separated orchards in Massachusetts was 52 cents per tree, and the 



