BULLETIN No. 170. 



APPLE DISEASES CAUSED BY 



Coryncum foliicoliim Fckl. and Phoma niali Schulz et Sacc. 

 Charles E. Lewis. 



Careful examination of the fungi associated with diseases 

 of the apple in Alaine shows that they may be divided into 

 classes according to the extent of their parasitism. Some of 

 these fungi have been carefully studied at a number of different 

 places and have been shown to be the cause of disease under 

 the conditions which exist in those localities, others have been 

 repeatedly shown to be saprophytes, others have been either 

 regarded as saprophytes or have not been studied sufficiently to 

 determine to what extent they are parasites, and still others 

 which have been usually regarded as parasites because of their 

 association with diseased conditions are found in some cases 

 to be saprophytes. 



Since under certain special conditions, a fungus which is 

 usually saprophytic may take on a parasitic habit and a fungus 

 which is a parasite under one set of conditions may lose the 

 power to cause disease under other conditions, it becomes neces- 

 sary to study the fungi associated with the diseases of any host 

 plant in a given locality as to their ability to cause disease. 

 In the studies of apple diseases which are now under way at 

 the Maine Experiment Station, fungi have been isolated from 

 diseased leaves, wood, and fruit and these fungi are being 

 studied as to the extent to which they cause disease when the 

 different parts of the plant are inoculated from pure cultures. 



Alost of the results of this work will be given in later publi- 

 cations but at the present time it seems desirable to give the 

 results of the study of two fungi. In the literature there is very 

 little reference to either of these as a cause of disease, although 

 each belongs to a genus in which there are species which are 

 parasites of great economic importance. 



