304 



DISEASES OF ECONOMIC PLANTS 



Fig. 133. — Tobacco leaf showing leaf spot 

 (cercosporose). After Conn. Exp. Sta. 



The disease was first 

 described hy Sturgis ' 

 from specimens sent from 

 South Carolina. It was 

 then very destructive, 

 practically ruining the 

 crop. A damage of $1000 

 to one crop alone was 

 noted. It has since con- 

 tinued as a troublesome 

 pest. 



The use of Bordeaux 

 early in the season is per- 

 missible and advanta- 

 geous. 



White speck {Macro- 

 sporium tabacinum Ell. & 

 Ev.). — White speck con- 

 sists of small, circular 

 spots, rusty red or brown 

 at first, but later with 

 blanched centers, upon 

 which the scattered hy- 

 phse grow. 



Brown spot {Macro- 

 sporium longipes Ell. & 

 Ev.). — This spot differs 

 from the above in its rusty 

 brown color and in having 



' Sturgis, W. C, Conn. State Agr. Exp. Sta. Rpt. 20, p. 273, 1896. 



