FUNGI AFFECTING THE CABBAGE AND 



CAULIFLOWER 



The Club Root 



Plasmodiophora brassicce 



The club-root of cabbage, cauliflower, turnip and 

 other cruciferous j^lants, is well known to most garden- 

 ers in the eastern and central States. It is also found in 

 many parts of Europe, having been known in Scotland 

 for more than a century. The disease is sometimes 

 called "clump foot," ^^club foot," and '^fingers and 

 toes;" it often does great damage, sometimes destroy- 

 ing entire crops. The trouble has been attributed to 

 various causes, but it is now definitely established that 

 the agency chiefly concerned is a low form of fungus — 

 one of the slime-molds — the vegetative portion of which 

 does not even develop mycelium threads, but grows as a 

 semi-liquid slimy mass. This gains access to the tissues 

 of the young roots and develops in the cells, causing the 

 tissues to become malformed in various ways. After 

 developing in this way awhile the mold produces innu- 

 merable spores, which are set free by the rotting of the 

 root tissue, and left in the soil. Here they germinate 

 by the production of zoospores, which remain in the 

 soil apparently indefinitely, and penetrate — when oppor- 

 tunity offers — the thin-walled cells of roots and rootlets, 

 thus continuing the cycle of existence. 



The disease commonly attacks seedlings in the seed 

 bed. Such plants begin an abnormal root-development, 



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