230 



ELEMENTS OF AGRICULTURE 



plums are seldom sprayed unless they are infected with 

 the San Jose scale. In many regions, apples are commonly 

 sprayed three times, once just before the blossoms 

 open, once just as the petals fall, and again 10 to 14 days 

 later. The mixture used is three to four pounds of copper 

 sulphate, four to six pounds of lime, 

 and one-half pound of Paris green in 

 50 gallons of water. (See page 263.) 



The effects of spraying apple trees 

 in Orleans county, New York, in 1904, 

 were as follows: 



Unsprayed, $92 average income per acre. 

 Sprayed once, $116 average income per 



acre. 

 Sprayed twice, $127 average income per 



acre. 

 Sprayed three times, $139 average income 



per acre. 



216. Pruning. Pruning is neces- 

 sary in order to thin the top, other- 

 wise the competition among the 

 branches injures all of them. The 

 main branches of a fruit tree should 

 be so arranged as to prevent splitting. 



Trees that are to stand many years 

 should be so pruned as to preserve 

 sound trunks. This is of less conse- 

 quence with short-lived trees like the 

 peach. Correct pruning depends on 

 a knowledge of the cambium layer. 

 The living and growing part of a tree is the cambium 

 layer. This is a tissue that lies on the outside of the wood 



FIG. 116. A bad crotch. 

 One of the limbs should be 

 removed or the tree will be 

 likely to split. 



