FUNGI AFFECTING CELERY 



The Celery Blight 



Cercospora apii 



The common blight of celery, sometimes incorrectly 

 called the rust, is a destructive 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 sjiots 

 increase rapidly in size, 

 and soon chano;e to a 

 brown color. In a short 

 time 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 spores. When one 

 of these falls upon a 

 moist celery 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 



FIG. 61. CELERY LEAF SHOWING 

 BLIGHT. 



