DRUPACEOUS FRUITS 143 



of peaches. When plums begin to ripen or are just turn- 

 ing in color, small round patches, pale greenish or gray- 

 ish in color and not larger than the head of a pin, 

 appear. These increase in size, in some cases to a centi- 

 meter across. 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 the 

 peach scab will apply in this case. 



Blight (Bacillus amylovorus (Burr.) De Toni). — The 

 blight of the apple and pear have been discussed on 

 preceding pages. A very similar blight is rarely known ^ 

 to affect the plum tree, and careful studies by Jones ^ show 

 that the diseases on plum and pear are identical. While 

 the plum blight is exceedingly rare, it is important that 

 fruit growers should recognize that the disease is identical 

 with pear blight, since this knowledge will help very ma- 

 terially in its control. 



For treatment see pear. 



Yellows. See peach. 



Brown rot {Sderotinia fructigena (Pers.) Schroet.). — 

 Brown rot is very serious with the plum as it is with the 

 peach and cherry. The loss in Ohio in one year was esti- 

 mated at $25,000. 



For description and treatment see peach. 



Powdery mildew, podosphaerose. See cherry. 



Rust {Puccinia Pruni-spinosce Pers.). — The rust of the 



1 Whetzel, H. H., & .Stewart, V. B., N.Y. (Cornell) Agr. Exp. Sta. Bui. 

 272. 



2 Jones, L. R., Centrbl. f. Bakt. Parasitenk. u. Infek. 2 (Abt. II), 825. 



