306 MANUAL OF FRUIT DISEASES 



REFERENCES ON PEACH-GUMMOSIS 



Caesar, L. Peach diseases. Cankers and gumming of peach trees. 



Ontario Agr. Dept. Bui. 201 : 38-40. 1912. 

 Selby, A. D. Preliminary report upon diseases of the peach. 3. A 



twig disease with gum-flow. Ohio Agr. Exp. Sta. Bui. 92 : 199- 



206. 1898. 

 Taft, L. R. Spraying calendar for 1898. Gum-disease of the peach. 



Michigan Agr. Exp. Sta. Bui. 155 : 304. 1898. 



BLACK-SPOT 



Caused by Bacterium Pruni E. F. Smith 



This peach trouble is known only in the eastern and central 

 United States; so far it has not been reported in any other 

 region of the globe. Not only is its range limited but its 

 history is rather brief, and its importance has prompted scien- 

 tific writings only during the past decade. But in the short 

 history of black-spot, or shot-hole as it is frequently called, it 

 has assumed a very prominent role in the culture of stone-fruits 

 in the humid regions of the South. It is less important in 

 the North and East. In Missouri it is rated as one of the worst 

 of fruit diseases. The losses induced by the black-spot patho- 

 gene are not easily reckoned. But in Missouri it has been 

 found that from 1 to 10 per cent of the Elberta peach fruits 

 is injured in well cared for orchards, and from 25 to 75 per 

 cent in poorly managed orchards. All affected fruits are 

 graded second class. Furthermore, such fruits do not ship well, 

 often being completely rotted in transit as a result of rot-fungi 

 which gain entrance through black-spot lesions. The injury 

 is not confined to the fruit alone, but foliage is attacked. Dis- 

 eased foliage is less efficient than healthy leaves, and so the 

 vitality of the tree suffers. This also results, in the event of 

 early spring infection, in the reduction in size and quality of 

 the fruit. Severe leaf-injury also results in a reduction in 

 the vitality of the fruit-buds and even prevents the formation 



