4 



Protection of crops from the attacks of fungi and insects by 

 the interposition of some sort of barrier is perhaps the oldest 

 and most widely applied of these four principles of control. 

 It is upon this principle that spraying is based. Spraying is, 

 in most cases, a method of protection. It has been for nearly 

 four decades the chief weapon of the fruit grower in combating 

 the insects and fungi that attack his crops. 



Immunization, the development of immune or highly resistant 

 strains or varieties of cultivated crops, has but recently received 

 the practical consideration which its promise of profitable appli- 

 cation has warranted from the. first. The perennial nature of 

 the crops of the fruit grower makes its application to their 

 problems of less immediate promise than in the case of the 

 annual crops of the cereal or field crop farmer. 



Our attention, therefore, to-day will be directed to a con- 

 sideration of the principle of protection and more specifically 

 to spraying as a method based upon this principle. 



Definition. 

 Spraying consists in the application of fungicides and insecti- 

 cides in liquid form for the protection of our fruit crops. 

 While, in general, spraying is to be looked upon as a method 

 of protection, it is in a few cases a distinctly eradication method 

 as, for example, in the case of the control of peach leaf curl or 

 San Jose scale. We shall, however, confine ourselves to-day 

 chiefly to its applications in the control of scab and codling 

 moth of apples and the brown rot and curculio of the peach. 



History. 



A brief consideration of the history of spraying, particularly 

 in the United States, will afford a desirable background for 

 a better understanding of the practice as now in vogue in this 

 country. 



Spraying, as a measure for protection against pests and 

 diseases of plants, may be said to have been introduced into 

 the United States about 1885. Following the discovery of 

 Bordeaux mixture by that noted Frenchman Millardet, in 

 France in 1883, the mixture was almost immediately tried 



