SPRAYING 



231 



official inspectors ; (2) give the pests as little chance as possible, by 

 destroying all breeding places, such as volunteer, neglected trees, 

 rubbish which may harbor insects over winter, and secondary hosts 

 which may help to propagate injurious insects and plant diseases ; 

 (3) keep trees healthy and vigorous ; (4) prevent decay or the en- 

 trance of disease into the trunk or branches of the tree by intelli- 

 gent pruning and by protecting the exposed surfaces ; (5) clean 

 out, disinfect, and fill the holes if decay does start ; (6) gather from 

 the tree and the ground all injured or diseased fruit and destroy it. 



Fig. 105. A power sprayer 

 A large type of practical orchard sprayer out in the orchard ready for work 



The good effects of cultivation in the orchard are by no means 

 confined to making available the food supplies contained in the 

 soil and to the conservation of moisture. Cultivation also assists 

 materially in controlling the fungous and insect pests of the orchard, 

 particularly the latter. 



It is an old story that orchards should not be sprayed with any 

 arsenical spray during their bloom, both for fear of killing the 

 bees that pollinate them and for fear the spray will itself injure 

 the stigmas or pollen. Recent investigation, however, seems to 

 show that spraying an apple tree in bloom does not do so much 

 damage to bees visiting the tree as has been supposed ; though 

 there is still room for further test experiments. But, on the other 



