FUNGI AFFECTING CELERY 



The Celery Blight 



Cercospora apii 



The common blight of celery^ sometimes incorrectly 

 called the rust, is a destructiye and widespread disease^ 

 which appears from the middle to the last of summer. 



Its presence is usually 

 first seen in the shape 

 of small^ irregular, yel- 

 lowish-green spots, less 

 than a quarter of an 

 inch in diameter, upon 

 the leaves. These spots 

 increase rapidly in size, 

 and soon change to a 

 brown color. In a short 

 tiine they so spread as 

 to form great blotches, 

 involving a large por- 

 tion of the leaf, which 

 may finally wither and 

 die. The fungus caus- 

 ing this disease repro- 

 duces by means of elon- 

 gate sj)ores. TThen one 

 of these falls upon a 

 FIG. 61. CELERY LEAF sHowixG moist cclcry leaf it ger- 



minates by sending out 

 a long tube, which penetrates the leaf^ and develops the 

 mycelium among the cells. Here it continues growing 



144 



