ROOT CROPS AND OTHER COMPARABLE FORAGES 595 



family, may be attacked by various diseases. One of 

 the most common is club-root, or " finger and toe disease," 

 caused by the myxomycete Plasmodiophora brassicce. 

 This causes the roots to become greatly enlarged and mal- 

 formed. There is no direct remedy, and the organism 

 causing the disease will live in the ground several years. 

 Rotation is the best means of control. 



713. Yields of kale, cabbage and other brassicaceous 

 plants. The relative yields of various brassicaceous 

 plants other than root crops is well shown by the long- 

 continued tests at the Ontario Agricultural College. In 

 these trials the different varieties of cabbage taken to- 

 gether outyield any of the related groups ; namely, rape, 

 kale, collards and similar plants. 



JERUSALEM ARTICHOKE ( Helianthus tuberosus) 



714. The Jerusalem artichoke or topinambur is a native 

 of America from Ontario to Saskatchewan south to Georgia 

 and Arkansas. It was cultivated by the Indians for the 

 edible tubers, and was early introduced into Europe. 

 The artichoke is a sunflower with medium-sized heads, 

 subcordate petioled leaves, and clustered tuberous roots. 

 There are several varieties, distinguished by the color of 

 the tubers, white, yellow or red, and by the shape of 

 the leaves, either narrow or broad. 



Artichokes seem to be less cultivated now than formerly, 

 and are apparently relatively more important in Europe 

 than in America. They are cultivated much after the 

 manner of potatoes, the tubers being planted in hills 20 

 inches apart each way, or better, in rows 24 to 30 inches 

 wide. The crop is permitted to grow until the plants are 

 killed by frost. Artichokes are valuable as forage chiefly 

 for hogs, and they are usually harvested by turning these 



