FUNGOUS DISEASES. II7 



account for the latter, as such weeds growing in 

 waste land serve to keep up continuous germs of 

 the disease. 



Precautions and Treatment. — ^From a consider- 

 ation of the nature of the club root fungus and a 

 knowledge of the different kinds of plants infested 

 by it, there may be some suggestions gathered as to 

 preventive measures. When it is understood that 

 the club root and all the injury to the crop accom- 

 panying it is due to an internal subterranean para- 

 site, it becomes evident that no treatment to which 

 the infested plant may be subjected can give promise 

 of a cure. Preventive measures must be relied upon, 

 and, in the first place, all the refuse of a cabbage, 

 turnip or other infested crop should be removed from 

 the soil and burned. To leave cabbage stumps in 

 the field, to feed them to live stock, or to throw them 

 in the compost heaps, are three of the worst methods 

 of propagating and spreading the malady on the 

 farm. It is not enough to destroy the roots, for the 

 Plasmodiophora is f oimd also in the leaves and stems 

 of infested plants. Seedlings of cruciferous plants 

 grown in the hotbed should be examined carefully, 

 and, if they show signs of the club root, consigned 

 to the fire. If only a few portions of the plants are 

 clubbed, it may be wise to discard the whole lot 

 rather than lose the crop in the field. Start with 

 healthy plants. In view of the fact that the soil may 

 become more or less impregnated with the germs 

 during the growth of a crop susceptible to the 

 Plasmodiophora, it is evident that a wise precaution 

 consists in a judicious rotation of crops. Just what 

 that rotation should be, is a question for each grower 

 to decide for himselt but, for the best results, cab- 



