118 



DISEASES OF ECONOMIC PLANTS 



The results are shown in the accompanying figures. The 

 trees, located in Illinois, were sprayed May 20, June 

 20, and July 17, the first spra3ang being about a month 

 after blooming, the second just after picking. 



Fig. 52. — Brown rot (sclerotiniose) showing various stages of decay. 

 After Clinton. 



Rust. See peach. 



Black knot {Plowrightia morbosa (Schw.) Sacc). — As 

 upon the plum, this knot causes serious injury to the cherry. 

 In some sections it has spread to the wild cherry and 

 plum trees in such abundance as to render control prac- 

 tically impossible, and in this way it has killed the cherrjr- 

 growing industry. Taken in time it is easy to control. 

 See plum. 



