CHAPTER lo 



DISEASES OF CAULIFLOWER 



Indoor cauliflower seems to be subject to less dis- 

 eases than that grown out of doors. The troubles 

 which attack this plant are practically the same as 

 those which are found on the cabbage. 



Club Root 



Caused by Flasmodiophora bras sic ce Wor. 



Symptoms. Affected plants show a wilting of the 

 foliage in the day, although recovering in the eve- 

 ning or during cloudy weather. Diseased plants are 

 dwarfed, pale, and sickly looking. The seat of the 

 trouble is at the roots. The latter swell considerably 

 in size, often taking on the form of a hernia (fig. 17, 

 a-c). The disease is more severe on seedlings in the 

 seed bed, from whence it is carried to the field or to 

 the greenhouse. 



The Organism. Club root is caused by a slime 

 mold. The spores of the parasite (fig. 17, d.) are 

 nearly round and possess a transparent and refrac- 

 tive cell wall. The first signs of germination are a 

 swelling of the spores, followed later by a bulging 

 at one side. The inner pressure exerted splits the 

 spore wall, thus permitting the protoplasm (swarm 



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