1908.] 



Apple " Scab " or " Black Spot." 



183 



" scab " has been prevalent for a number of seasons, that 

 the young apples on certain varieties of trees become so 

 severely attacked that they present the appearance repro- 

 duced in the photograph in Fig. i. The further growth of 

 apples, which are attacked as severely as this, is almost entirely 

 prevented. If, as in the case of less susceptible varieties of 

 apples, the disease does not altogether prevent further growth, 

 the apple by the time it has attained full size is either mis- 

 shapen owing to the diseased parts having been prevented 

 from developing, or its appearance is disfigured by the presence 

 of a number of " black spots " or " scabs " on the skin. 



fig. I. — Young apples attacked by the Apple Scab or " Black Spot" fungus; 

 showing the cracking seen in severe attacks of this disease. 



Now the presence of " scabby " fruit on a tree is almost 

 certain indication that the disease is existing on the leaves or 

 young wood of the same tree, or of neighbouring trees. And it 

 is to the prevention of the growth of the fungus on the leaves- 

 that the grower should pay special attention, since if the 

 leaves are sprayed and kept clean, the disease can be easily 

 suppressed. 



If the leaves are examined closely, they will be found to 

 bear the fungus, usually on the upper surface of the leaf, but 

 often on the lower surface as well. The exact appearance of 

 the disease on the leaf of the apple varies considerably 

 according to the variety, but in every case the part actually 



