142 FUNGI AND FUNGICIDES 



less, one of the best preventive methods. Crops on 

 land which has previously been planted to cabbages or 

 turnips are most liable to suffer, but the disease is said 



FIG. 60. CLUB ROOT OF SHEPHERD'S PURSE. 



sometimes to appear on new land. Crops on limestone 

 soils are usually quite free from attack. 



Clean farming, involving the removal and destruc- 

 tion, by burning, of all refuse of the cabbage or turnip 



