24 



BOARD OF AGlilCULTUKE. [Pub. Doc. 



Some of the Commo7iest Diseases of the Aiyple, classified as to Cause. 



Name of Disease. 



Cause. 



1. Scab of leaf and fruit, 



2. Rust of leaves, .... 



3. Leaf spot, 



4. Sooty blotch of fruit, 



5. Canker of limbs and black rot of 



fi-uit. 

 G. Fire-bliglit of twigs, and possibly 

 some body blight. 



7. Brown spot of fruit, 



8. Scald of the fruit, . . . . 



9. Frost bands on the fruit, 



10. Russeting of sprayed fruit, 



11. Codlin moth 



12. Apple maggot, or " railroad worm," 



1.3. Scales, 



14. Borers, 



A fungus, — Venturia hiaequalls. 



A fungus, — Gymnosporanzinm macro- 

 pus. 

 A fungus, — Phyllostictu plrlna. 



A fmigus, — Phyllachora pomiffena. 



A fmigus, — Sphaero})sis malorum. 



Bacteria, — Bacillus amylovorus. 



A physiological disorder, probably asso- 

 ciated with water distribution. 



A physiological disorder, resulting in 

 improper maturing. 



A physiological disorder, the result of 

 climatic conditions. 



A physiological disorder, resultuig from 

 the poi.sonous action of spray^ com- 

 pounds imder certain conditions. 



An insect, — Carpocapsa pominella. 



An msect, — Trypeta pominella. 

 Insecfe, — Aspidotus perniciosus, etc. 

 Insects, — Chrysohothrisfemorata, etc. 



I have purposely orouped these in similar order, so that, 

 by comparing the maladies of the one o-roup with those of 

 the other, number by number, the striking parallelism will 

 be apparent. This parallelism holds not onl}^ as to the com- 

 mon names of the diseases, but in their classification as to 

 general cause. It has therefore appealed to the scientific 

 specialist, — the man whose work is primarily in the labora- 

 tory inquiring into the specific causes of these various mal- 

 adies, for information can only be handled in the scientific 

 spirit in proportion as it is classified. Nor would I mini- 

 mize the importance to the practical man of seeing and learn- 

 ing the significance of the above scheme of classification, and 

 even of committing to memory the Latin names of his chief 

 enemies. It is a o-reat aid to intellio-ence and definiteness in 

 thinking thus clearly to group the causes of these plant mal- 

 adies under the four heads, — insect, fungous, bacterial and 

 physiological. 



But I would emphasize the point that the help thus com- 



