146 



Diseases of Economic Plants 



considerable damage, causing 

 premature falling of leaves. The 

 rust appears as brown spots 

 upon the leaf. 



Leaf-blight {Cercospora bol- 

 leana (Thiim.) Speg.). — This 

 blight has been noted in the 

 United States, though but slight 

 attention has been given it. It 

 causes injury similar to that of 



Fig. 76. — Fig in well-advanced rust, 

 of fruit-rot. Original. 



Other diseases of the fig are: 

 a Rhizoctonia leaf-blight; a root-knot due to nematodes; 

 Southern-blight (Sclerotium rolfsii) ; Cankers due to Mac- 

 rophoma, Libertella, and Tubercularia; Limb-blight due to 

 Corticium; Root-rot (Ozonium) and Yellow-rust {Fusarium). 

 Black-smut ^^^ {Sterigmatocystis) may affect as high as 15 per 

 cent of the fruits in some instances. 



GUAVA 



Ripe-rot {Glomerella 

 disease was 

 described 

 from green- 

 house mate- 

 rial collected 

 at Washing- 

 ton, D. C, 

 and after- 

 ward it was 

 reported 

 from Florida 

 and Cali- 

 fornia. The 

 affected 

 fruit shows 

 circu lar, 



i (G. Del.) Sheldon). — This 



Fig. 77. — Guava affected with ripe- rot. After Rumsey. 



