126 Diseases of Truck Crops 



Symptoms. It is characterized by minute brown- 

 ish spots on the leaves (fig. 20 i and k). On the roots 

 it is manifested as a dry black rot extending deep in 

 the interior. The outside of the root has a shrunken 

 appearance which closely follows the seat of the inte- 

 rior rotting. 



Control. In the field, the disease first starts in the 

 seed bed. Spraying with 4-4-50 Bordeaux is recom- 

 mended. Two applications may suffice. In the 

 field, spraying has not as yet given promising results. 

 Clean culture and rotation will eventually free a field 

 from the disease. 



The disease is introduced upon the seeds which 

 frequently bear the fruiting bodies of the fungus. It 

 has been shown that disinfection of the seed will 

 prevent the carrying over of the disease. 



LEAF SPOT 

 Caused by Cercospora beticola Sacc. 



There is perhaps no beet disease that is of greater 

 economic importance than leaf spot. The trouble is 

 well known to truckers and it seems to be found where- 

 ever beets can thrive. 



Symptoms. The disease first makes its appearance 

 on the leaves as tiny circular whitish spots. These 

 gradually increase in size and assume a brownish 

 color. The spots soon increase in numbers and 

 involve the entire area of the leaf (fig. 20 g), which 

 becomes dry and brittle. Leaf spots attack the outer 



