546 



Minnesota Plant Diseases. 



the soil. Cabbages, radishes, turnips and even common weeds 

 of the mustard family, such as shepherd's purse, when planted 

 in such infected soil, will almost certainly become infected. 

 Even the transferrence of soil from such an infected field to an 

 uninfected one, as by clinging to wagon wheels or farm imple- 

 ments may carry infection with it. Manure from cows fed with 

 clubbed roots will easily infect crops. 



No entirely successful treatment of club root is known. A 

 number of varieties of turnips have been tested and the ruta- 

 baga was found most susceptible. In general, it seems that those 



turnips with branching and 

 deeply seated roots are most 

 susceptible, while those that 

 do not penetrate deeply and 

 which are not much branched 

 are least affected. Experi- 

 ments also seem to indicate 

 that buckwheat grown in tur- 

 nip land has a favorable effect 

 on the resistance to club root. 

 In general, infected fields 

 should not be used for the 

 same crop — or for any plants 

 of the mustard family — for 

 several years, as the slime 

 mold seems to be able to re- 

 tain its vitality at least for two 

 or three years. The infection 

 of new fields must be carefully 

 avoided, by preventing the 

 transference of soil or refuse 

 from the infected fields to other plots. The application of a 

 coating of lime to the soil in the proportion of seventy-five 

 bushels to the acre has been tested and has given very satisfac- 

 tory results. Weeds of the mustard family must be carefully 

 held in check. 



Fig. ISO. — Club root of cabbage, 

 ton. 



After Clin- 



