856 



The Sclerotinias ai'e characteiizcd during the vegetative stage by the 

 formation of sclerotia. Tlie sclerotia are white wlien first formed, but 

 soon the outer cellular layers become black and more or less roughened. 

 These sclerotia are usually formed abundantly on the diseased root, es- 

 pecially during the later stages, thus affording an easy means of dis- 

 tinguishing these diseases. 



There are two distinct types of Sclerotinial diseases of ginseng; one 

 in which the entire root becomes black and covered with hard black 

 sclerotia and the other in which the root retains its natural color, but in 

 v.hicli a number of black sclerotia are developed on the outside. The 

 former type is known as Black Rot and is familiar enough in those gar- 

 dens infested l)y it. The diseases of the latter tyi>e have collectively gone 

 under the name Crown liot, although it is l)y no moans certain that the 

 various diseases given this name have all Ixhmi caused l)y tlie same or- 

 ganism. 



It was with the object of determining the name and characteristics of 

 eacli organism connected with these diseases and of finding some means 

 for successfully combating them that the present investigation was under- 

 taken. The work during the summer of 1910 was carried on at Cornell 

 University under tlie direction of Trof. II. II. Wlietzel, to whom grateful 

 acknowledgments are due for the use of his private notes collected during 

 Ids work on ginseng diseases. Tlie work was continued during the pasi. 

 winter in the laboratories of the Botanical Department of Wabash Col- 

 lege under the direction of Prof. M. B. Thomas. 



BLACK ROT. 



The first recorded mention of tliis disease was by Van Hook (■()4 » 

 from a ginseng garden in New York. However, with the increased culti- 

 vation of ginseng it has spread, until last summer it was reported not only 

 from several counties in New York but from other States as well. While 

 to the author's knowledge, its destruction has been extensive in only a 

 few cases, it is well worth while to be on the lookout for it, as tliis dis- 

 ease is very difRcult to eradicate when once it obtains a foothold. 



Roots attacked by Black Bot are coal black in color when dug, chang- 

 ing to a dirty gray when dried. 'I'hcy are devoid of all their small fibrous 



(•04) Van Hook, J. M. Diseases of Ginseng. New Yorlt (Cornell) Agr. E.xp. 

 Sta. Bui. 219: 1. c. 181-182. 1904. 



