190/.] 



Apple-tree Mildew. 



359 



The winter or ascigerous form of fruit is everywhere rare, 

 and in this country has only once been found in very small 

 quantity in an orchard at Mortlake. This form of fruit is 

 certainly too local in its occurrence to account for the universal 

 distribution of the mildew in the spring, which consequently 



L i 



4 



APPLE-TREE MILDEW. 



must originate either from the conidia or summer form of 

 fruit, which would imply the power on their part of germinating 

 the year following their production, or from hibernating 

 mycelium. For the former of these two alternatives there is 

 no precedent. 



As a rule the fungus completely checks the growth of the 

 branches, consequently all the leaves that under normal 

 conditions would have been scattered at intervals on a long 

 shoot, are crowded into a rosette at the end of a branch of 



