CHAPTER VI 



CONTROLLING INSECTS AND DISEASES 



The control of insects and diseases is one of the major 

 problems of the fruit grower. The destructive work of these 

 organisms reduces both the quantity and the quality of the 

 fruit, the vitality and life of the tree may be impaired, and the 

 investment in materials, equipment and labor to control them 

 constitutes one of the chief items of expense in fruit production. 



Insects and diseases cause annual losses that run into 

 staggering sums. First is the direct loss from the work of the 

 organisms, and then the expense of materials and labor, of 

 investments in equipment, in order to control them, as well 

 as the reduction in vitality of the tree or plants, affecting 

 productivity and perhaps length of life. One authority states 

 that from 20 to 40 percent of the fruit crop in the United 

 States is destroyed each year by insects alone. The problem 

 is not merely to find materials that will control but materials 

 that the grower can afford to use and that will control the 

 organisms without injury to the fruit plant. 



Most kinds of fruit cannot be changed from one field to 

 another on a short rotation, as may be done with annual crops. 

 An apple orchard is fixed for the better part of a lifetime. 

 The fruit grower cannot employ rotation as one of his major 

 weapons in insect and disease control, as is frequently done 

 with annual crops. 



There are natural forces which exert a measure of control 

 over insects and diseases. Late frosts, cold winters, dry 

 spells all have their effects. Diseases among insects, predaceous 

 and parasitic insects and even birds may greatly reduce the 



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