VENTURIA 



205 



able from half to the entire crop, in addition to the injury 

 caused to the tree. It is present wherever the apple is 

 grown, and until recently was supposed to be due to a fungus 

 called Fusidadium dendriticum (Fuckel). The many re- 

 searches of Aderhold on the Fusicladium of fruit-trees have 

 clearly proved that the fungus concerned with apple scab is 

 Venturia inequalis^ Aderhold ( = Sphaerella inaequalis, Cke.), 





FIG. 57. Venturia inaequalis. i, conidial 

 form of fungus on apple leaf ; 2, conidial form of 

 fungus on apple, causing scab ; 3, fruit of conidial 

 form of fungus, mag. 



of which the Fusicladium is a conidial condition. It was at 

 one time considered that the fungus was confined to the 

 fruit, then it became known that it occurred on the leaves, 

 at a still later period I announced its presence on the young 

 shoots, since which time it has more than once been redis- 

 covered on the twigs, and paraded as something new. On the 

 twigs the fungus forms extended blackish-olive patches, at 

 first covered by the epidermis or skin of the shoot, which 

 eventually becomes ruptured and torn, or completely thrown 



