116 The Botanical Gazette. [April, 
a tree of the hedge rows, and the wild red cherry, P. Pennsyl- 
vanica, are also attacked. 
It is evident from the illustrations that have been given of 
the diseases of the genus Prunus that there must be a close 
relation existing between the wild plants and those grown for 
fruit. What with the plum pockets, the curl, rust, and black- 
knot, it is evident that more attention needs tobe paid to the 
wild hosts of fungi of cultivated plants before the latter can 
be free from their attacks of their present enemies. 
There is a mildew, Podosphera tridactyla (Wallr.) so wide- 
spread that it cannot be assigned to any one crop. Because 
very destructive upon the apple and particularly seedlings in 
the nursery it has been called the apple leaf mildew, but im 
some localities cherries, both old and young, suffer severely 
from it. It preys upon the quince, several species of the 
hawthorn, the June berry and various spireas. It seems to 
¢ a well established fact that plants that are closely related 
of grapes. In like manner at the New Jersey experiment 
Station it has been found that one of the worst enemies to the 
Sweet potato is identical with a serious disease of egg plants. 
There seems little in common between the sweet potato and 
the ese plant and yet in the face of the fact of a common ef 
emy it may suggest the importance of not following one ¢f0P 
found that much damage to the cucurbits generally was = 
to the bacterial disease. het 
Space forbids even the briefest mention of many Ord 
cases where plants wild affect the health of plants cultiva 
