194 MAINE AGRICULTURAL EXPERIMENT STATION. I9I4. 



we have made recently in Maine, particularly during the past 

 year, however, lead us to the conclusion that a more extended 

 study of the subject will show that this position is by no means 

 in accord with the facts. The significance of these observations 

 and of the results of the experiments here reported is more 

 evident when the latter are considered in connection with some 

 of the previous work in this country upon the parasitism of 

 the same fungus or closely related species. No attempt is made, 

 however, to review the literature upon Rhizoctonia as a whole. 



Previous Studies in America upon Plant Diseases Caused by 



Rhizoctonia. ' 



The first important report on the economic aspects of Rhizoctonia in 

 America is that of Pammel (10) in 1891, who studied a beet root-rot 

 in Iowa which he stated was caused by Rhisoctdnia betae Yiuhn {R. 

 solani Kiihn). The following year Atkinson (i) published the details 

 of certain studies and experiments in which he showed conclusively 

 that a sterile fungus was the cause of "sore-shin" or damping off of 

 cotton in Alabama. Later, in 1905, the same writer (2) found a similar 

 parasite causing a damping off of beans, lettuce, radishes, egg plants 

 and cabbages in New York. Duggar (4) in 1899 reports Rhizoctonia 

 as the cause of beet root-rot in New York and also as producing a 

 damping off of beet seedlings, lettuce, beans, radishes, cucumbers and 

 occasionally many other seedlings, as well as a crown rot of radishes. 



A very important contribution to the literature upon Rhizoctonia as 

 a cause of plant diseases in America is that of Duggar and Stewart 

 (5, 6) which appeared in 1901. They showed that this fungus attacks a 

 large number of different hosts, including some 30 species of cultivated 

 plants in the United States. Their conclusions regarding its parasitism 

 are briefly stated in the following paragraph quoted from the summary : 



"Rhizoctonia is the cause of a destructive root-rot of the sugar beet, 

 a destructive stem-rot of the carnation, a leaf-rot of greenhouse lettuce, 

 a leaf-rot of ornamental asparagus, and a root-rot of the carrot ; and 

 is of common occurrence on the stems and tubers of the potato. It is a 

 frequent cause of damping-off of various seedling plants, such as beet, 

 carnation, celery, lettuce, cabbage, etc. It is also the suspected cause of 

 disease in the bean, rhubarb, cotton and some other plants. Further ob- 

 servations will probably show that many other plants are infested by it." 



Speaking specifically regarding Rhizoctonia on the potato they men- 

 tion the fact that while a disease caused by Rhizoctonia solani Kiihn 

 has long been common in Germany and known under the name of 

 "Grind" or "Pockenkrankheit" so far as they have been able to ascer- 

 tain there was no record of the occurrence of the fungus as a parasite 

 upon the potato in America. Their observations did show that potatoes 

 in the United States may be quite generally infested by a species of 



