2 MANUAL- 6F FRUIT DISEASES 



often, o'verlotiked, bring the total dollar loss far above the fancy 

 of fruit-glowers. It Would 'be difficult to set a figure which 

 would represent, accurately or even approximately, the losses 

 incurred each year. A few well-known examples may be tabu- 

 lated in order that some notion of the gravity of this source of 

 waste may be gained. One authority estimates from reliable 

 figures that there is an average annual loss of more than 

 $40,000,000 in the United States due to the failure to spray 

 apples. Such devastation, of course, is brought about both by 

 diseases, chiefly caused by fungi, and by insects, and it would 

 be quite impossible to assign the losses to the proper offender 

 in every case. Individual examples of losses follow : (1) bitter- 

 rot wrought damage to the apple-crop of the United States in 

 1900 amounting to $10,000,000 ; (2) black-rot canker induces an 

 annual loss of $750,000 in New York ; (3) blotch is said to have 

 caused in one county in Arkansas, in 1906, a loss of $950,000; 

 (4) rust, in 1912, was so destructive in West Virginia that actual 

 fruit-losses ranged from $2000 to $3000 an orchard. 



Apple diseases are important because of the nature of the 

 injury inflicted. Losses do not stop with damage to, or destruc- 

 tion of, the fruit. Blossoms may be killed ; the set of fruit may 

 be dropped; woody parts including twigs, limbs, trunks and 

 roots may be blighted, cankered or rotted; leaves may be 

 spotted and even dropped prematurely. It is indeed fortunate 

 that most of these types of troubles may be reduced to a point 

 where fruit-growing may still be carried on with pleasure and 

 profit. 



Most apple diseases are caused by fungi, but a few result from 

 the detrimental action of bacteria, and certain environmental 

 factors. The best-known, the most cosmopolitan, and the most 

 important of apple troubles generally is without question the 

 fungous disease known as apple-scab. Other diseases and in- 

 juries affecting this fruit are discussed somewhat in order of 

 their general prevalence and importance. 



