i8o 



DISEASES OF CULTIVATED PLANTS 



Distinguished by the soft not carbonaceous, highly- 

 coloured perithecia. 



Winter rot of potatoes. Probably the most destructive 

 disease attacking stored potatoes, where it is practically 

 always present to some extent. The most usual symptom of 

 the presence of the fungus is the gradual sinking and 

 wrinkling of the surface of the tuber. These sunken places 

 soon become sprinkled over with small, snow-white tufts of a 

 conidial form of fruit. When the tissue becomes disintegrated 

 by the mycelium, other organisms, bacteria, fungi, mites, etc., 



FlG. 47. Nectria solani. The Monosporium and Fusarium 

 stage ; the most frequently observed condition of ' winter-rot ' 

 in potatoes. 



quickly enter and assist in reducing the tuber to a semi- 

 liquid, rotten, strong-smelling mass. 



The disease has usually been attributed to Fusarium solani 

 (Pers.), but in reality the proper name of the fungus \sNedria 

 solani (Reinke and Berthold), of which the Fusarium is a 

 conidial form. The reason why the Fusarium has been con- 

 sidered as the primary and only cause of the disease is 

 because it is the most conspicuous feature present during the 

 state of disease most usually met with, and further, because 

 the Fusarium condition is capable of continuing the disease 

 alone, or without the intervention of the other phases 



