112 Report of the Botanist of thb 



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

 Rhizcctonia sclerotia, showing that the fungus exists in that 

 State. Specimens have also been received from Prof. J. F. Dug- 

 gar, 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 different parts of New York State, and Rhizoctonia has almost 

 always been found in greater or less abundance. Moreover, it 

 occurs in Alabama, Colorado, Iowa, Ohio, and Pennsylvania, and « 

 is probably very generally distributed. Recently the sclerotia 

 have been found abundantly in the markets of Washington, 

 D. C, on New 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 

 summer of 1890 Mr. F. A. Sirrine, at that time Assistant Bot- 

 anist at the Iowa Experiment Station, investigated a potato 

 disease which was doing serious damage on the Station farm. 

 He found the subterranean parts of the affected plants covered 

 with a certain fungus which he at once suspected of being the 

 cause of the trouble. He was unable to identify the fungus. 

 In the course of the investigation an important insect enemy of 

 the potato, the potato-stalk weevil, was discovered"^ in connec- 

 tion 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 the fungus was allowed to pass into obliv- 

 ion. Fortunately, Mr. Sirrine made and preserved a camera- 

 lucida pencil drawing of the fungus. This drawing shows that 

 the fungus studied by Mr. Sirrine was undoubtedly a Rhizoctonia. 

 We have inked in the drawing, without altering it in the least, 

 and publish it herewith. See Fig. 7. 



The Rhizoctonia attacks only the subterranean parts of the 

 potato plant. The hyph?e occur in the medulla, where they are 

 for the most part very slightly, if at all, colored, and on the out- 

 side of the stem and on the roots, where they are often light 



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



