Diseases and Pests of the Apple and Their Control 227 



pays more on the investment, and yet no other practice is 

 more likely to be slighted. Growers are now coming to 

 look on spraying as a form of insurance and well thought 

 out spray programs are being adopted in every region. 



While the last twenty years mark the period within 

 which spraying has come into general use in commercial 

 apple-growing, the history and development of spraying 

 plants dates back much further. There are authentic 

 records of trees having been " syringed " in Europe as 

 early as 1763. The history of spraying indicates that 

 this practice was probably not unknown much earlier than 

 this date. In 1872 paris green was first recommended as 

 an efficient spray material to be used against the canker- 

 worm in southern Illinois. Eight years later probably 

 the first experiment in the control of the codlin-moth with 

 the use of an arsenical poison was conducted in Michigan 

 by Cook who reported having successfully used London 

 purple in spraying crab-apple trees. In 1892 and 1893 

 arsenate of lead was introduced largely as an outgrowth 

 of the gipsy moth control work. While greater emphasis 

 was laid on insecticides in the early history of spraying, 

 the development of suitable spray materials for fungous 

 diseases was almost simultaneous. 



It is exceedingly difficult to describe exact methods of 

 spraying. Thoroughness is all important. Leaking 

 valves, leaking spray hose and faulty equipment should be 

 avoided. Spray applications should be made promptly 

 and at critical times, as delays are costly. For this reason 

 the equipment should be thoroughly gone over well in 

 advance of the season. 



It is impossible to fix a definite spray program which can 

 be followed absolutely. Continued rain or other inclem- 



