CHERRY DISEASES 187 



CROWN-GALL 

 Caused by Bacterium tumefaciens E. F. Smith and Townsend 



The crown-gall disease is so cosmopolitan in its host-range 

 that the cherry could not be expected to escape in all cases. 

 It is the younger trees that suffer, particularly if the knots, or 

 galls, surround the crowns. In the North, at least, it has been 

 observed that little injury is done to mature trees. Sometimes 

 trees planted with galls may outgrow the disease in a year or 

 so. It is not safe, however, to assume that this will always 

 occur; affected trees should not be used in plantings. (See 

 fuller discussion under Apple, page 108.) 



ARMILLARIA ROOT-ROT 

 Caused by Armillaria mellea (Fries) Quel. 



Among the stone fruit-trees affected by this root-disease the 

 cherry stands out as one of the most resistant. In the Pacific 

 Northwest, however, a few cases of root-rot caused by Armillaria 

 mellea have come to the attention of growers and plant patholo- 

 gists. Special discussion is not necessary here; see Apple, 

 page 96. 



LEAF-RUST 



Caused by Puccinia Pruni-spinosa Pers. 



On the leaves of many wild and cultivated cherries there is 

 frequently a rust-disease. It is said to occur more commonly 

 in the eastern United States. The same disease is found on 

 the peach and on wild and domesticated forms of the plum. 

 It is variously known as plum leaf-rust, prune-rust, peach-rust 

 and leaf-rust of cherry. (See fuller account under Plum, 

 page 377.) 



