Some Potato Diseases. 3 1 1 



and also many weeds, are susceptible to the attacks of this 

 fungus. 



Placing diseased portions of plants on the manure-heap or in 

 the piggery simply favours the continuation and spread of the 

 fungus, as the sclerotia remain active and vigorous when the 

 plant in which they originated is thoroughly decayed. The 

 sclerotia pass, without suffering injury, through the intestinal 

 canal of an animal. Hence, in all such cases, the sclerotia are 

 eventually returned to the land, where they produce fruit and 

 infect fresh crops. 



Gas-lime or quicklime should be applied to land where the 

 disease has existed. Potatoes for ' k sets " should be procured if 

 possible from districts free from the disease. 



The fungus causing rottenness of turnips and swedes, described 

 in this Journal {III., p. 120), also the potato disease in Ireland 

 called " Yellow blight," appear to be closely related to the 

 present disease, differing more especially in having a Botrytis 

 form of fruit. 



For information as to the life-history of the fungus 

 consult : 



Smith, W. G., Diseases of Field and Garden Crops, p. 125. 



De Bary, A. ; in Bot. Zeit. p. 485 (1886). 



Humphrey, T. ; in Bull. Agric. Exper. Station, Mass., 1892. 



Description oj Figures (Plate III.). 



1. Portion of a potato haulm showing a dense white felt of 

 mycelium, with sclerotia covering the surface just above the 

 ground-line. Higher up mycelium and sclerotia are seen in the 

 interior of the haulm. Nat. size. 



2. A sclerotium that remained on the ground throughout the 

 winter attached to a decayed fragment of potato haulm. During 

 the following summer it produced four long-stalked ascigerous 

 fruits, x 2. 



3. An ascus containing ripe spores, borne by the ascigerous 

 fruit, x 300. 



