74 J^ULLETIN 186. 



Peiina., was examined and found to contain a considerable number 

 of tubers bearing sclerotia. We have also seen the sclerotia on 

 tubers grown at jMattituek and Cutchogue. Mr. A. D. Selby has 

 sent us from Wooster, Ohio, potato stems and tubers bearing ItJtiz- 

 octonia sclerotia, showing that the fungus exists in thr.t State. 

 Specimens have also been received from Prof. J. F. Duggar, Auburn, 

 Ala., Mr F. M. Rolfs, Fort Collins, Colo., and Mrs. F. C. Stewart, 

 who found it at Bassett, Iowa. In short, during the past season' 

 many observations on potatoes have been made in dilferent parts of 

 New York State, and Rhizoctonia has almost always been found in 

 greater or less abundance. Moreover, it occurs in Alabama, Colo- 

 rado, Iowa, Ohio and Pennsylvania, and is probably very generally 

 distributed. Recently the sclerotia have been found abundantly in 

 the markets of AVashington, D. C, on Kew York and Michigan 

 potatoes, and also to a slight extent on one variety of potatoes 

 grown in Maryland. 



We have the following proof that the Rhizoctonia disease of 

 potatoes existed at Ames, Iowa, as long ago as 1890. In the sum- 

 mer of 1890 Mr. F. A. Sirrine, at that time Assistant Botanist at 

 the Iowa Experiment Station, investigated a potato disease which 

 was doing serious daniage on the Station farm. He found the sub- 

 terranean parts of the affected plants covered with a certain fungus 

 which he at once suspected of being tlie cause of the trouble. He 

 was unable to identify the fungus. In the course of the investiga- 

 tion an important insect enemy of the potato, the potato-stalk weevil, 

 was discovered^ in connection with the disease, and as it appeared 

 that this insect was responsible for at least the greater part of the 

 trouble, attention centered upon it and tlie fungus was allowed to 

 pass into oblivion. Fortunately, Mr. Sirrine made and preserved a 

 cameralucida pencil drawing of tlie fungus. This drawing shows 

 that the fungus studied by Mr. Sirrine was undoubtedly a Rhizoc- 

 tonia. We have inked in the drawing, without altering it in the 

 least, and publish it herewith. See Fig. 22. 



The Rhizoctonia attacks only the subterranean parts of the potato 

 plant. The hyphie occur in the medulla, where they are for the 



*ft 



See Iowa Exp. Sta, Bull. 11: 490. 



