Cauliflower Diseases 129 



and visible on both surfaces of the leaf. The 

 color is light brown to gray, with dry centers 

 surrounded by olive green or blue green borders 

 which shade off into the natural color of the leaf. 

 The outer edge of the spot is covered with the fruit 

 of the fungus. Spraying with 4-4-50 Bordeaux is 

 recommended. 



Black Mold 



Caused by Alternaria brassier (Berk.) Sacc. 



Affected leaves are covered with spots which are 

 nearly black on the under side of the leaf. The spots 

 are composed of a series of rings, the smaller ones 

 enclosed within the larger. There is no distinct 

 border separating the diseased portions from the 

 healthy; the spots gradually shade off into the 

 healthy tissue. Little is known of the causative 

 fungus or of the control of this disease. It is prob- 

 able that spraying with 4-4-50 Bordeaux will be of 

 value. 



Root Knot 



Caused by Heterodera radicicola (Greef) Mull. 



Root knot is characterized by small swellings on 

 the lateral feeding roots. For a description of the 

 parasite and methods of control, see p. 28. 



Celery (^Apium graveolens) 



Cultural Considerations. Celery has not yet taken 

 its place among the standard forced vegetables. It 



