The Apple. 45 



years from the graft or bud while slower-growing sorts are 

 preferably allowed to grow four years in the nursery. Old 

 and overgrown nursery trees should be avoided (23). 



Standard apple trees expected to attain full size should 

 be planted not less than 30 feet apart and in localities in 

 which the trees grow with much vigor, they should be 

 planted not less than 35 feet apart. 



48. Harmful parasites. The principal insects that in- 

 jure the fruit of the apple in America are the codlin or 

 codling moth, the apple maggot and the apple curculio; 

 those that injure the foliage are the tent caterpillar, plant 

 lice, the canker worms and leaf-rollers; those that injure 

 the trunk or branches are the apple-tree borers, the oyster- 

 shell bark-louse and the San Jose scale; and the one most 

 injurious to the roots is the woolly aphis. Of the fungi, 

 the apple scab and bitter rot affect the fruit, the fire blight 

 and the apple scab affect the foliage and young twigs, and 

 the apple canker affects the branches. These are consid- 

 ered in their order. 



49. The codling moth, {Carpocapsa pomonella). This in- 

 sect causes so-called wormy fruit in the apple and pear 

 (Fig. 8). It is one of the most serious of fruit insects, as 

 fruits infested by its larvos have little value either for mar- 

 ket or home use. In seasons of small crops, nearly the en- 

 tire yield of fruit is often damaged by this insect unless 

 preventive measures are used. It was imported into this 

 country from Europe and is now found in nearly all parts 

 of the United States and Canada east of the Rocky moun- 

 tains. 



The perfect insect is a moth that flies mostly at night 

 (g. Fig. 8). The first brood of moths appear about the time 

 the blossoms open, when the female deposits her eggs, usu- 



