Drupaceous Frait. 99 



damage before its presence is really known. Defoliation is 

 the chief injury. This checks starch production, and thus 

 impairs the tree's general vigor and productiveness, even 

 weakening the tree to such an extent that it cannot with- 

 stand the winter. As high as 80 per cent damage has been 

 reported. The loss in Ohio was estimated as $20,000 in one 

 year. Leaf -spot is especially injurious to nursery stock, as 

 it may interfere with successful budding and grafting. For 

 treatment, see cherry. 



Scab {Cladosporium carpophilum Thiim.). — Plum scab 

 appears as spots on the fruit, similar to the scab of peaches. 

 When plums begin to I'ipen or are just turning in color, small 

 round patches, pale-greenish or grayish in color and not 

 larger than the head of a pin, develop. These increase in 

 size, in some cases to a centimeter in diameter. In older 

 specimens the diseased spots are frequently confluent and of 

 darker brown color. In very old specimens, especially where 

 the fruit has undergone decomposition, the patches become 

 black and uneven. 



Treatment identical with that recommended for peach 

 scab will apply in this case. 



Wilt ^^^ {Lasiodiplodia triflorce Hig.). — Restricted to 

 the Japanese plum and hybrids, this injurious wilt has thus 

 far been observed only in Georgia, North Carolina, and 

 Alabama. Often the first symptom is a sudden wilting of the 

 leaves of a single branch or of a whole tree. At the base of 

 the wilted portion, the bark and cambium are dead and the 

 wood brown or black. The entire tree usually dies within a 

 year from the first observable wilt. The causal fungus ap- 

 pears to gain entrance to the host only through wounds, and 

 in the tree lives chiefly in the ducts. This disease, therefore, 

 presents a case with very few parallels, i. e. of a tree killed by 

 plugging of the veins by fungi. Prevention, by avoiding 

 wounds, or by disinfecting them when they occur, is the only 

 recourse. 



Silver-leaf (Stereum purpureum Fr.). — The leaves, though 

 normal in size and form, take on an ashen gray luster, this 



