292 



Journal of Agricultural Research 



Vol. V, No. 7 



roots were also made with a culture of Sclerotinia libertiana obtained 

 from lettuce from South Carolina. The procedure followed in the inocu- 

 lations was as follows : Healthy ginseng plants with the tops still attached 

 were selected and the soil carefulh^ removed from one side of the root. 

 By means of a flamed scalpel longitudinal cuts were made in the side of 

 the root. These cuts were approximately one-fourth of an inch in length 

 and about one-eighth in depth. A piece of agar containing mycelium 

 from young cultures was inserted within these cuts and covered with soil. 

 Check roots were treated in a similar manner. 



During the summer inoculations were made as shown in Table I. The 

 checks in every case remained healthy. 



Table I. — Results of the inoculation of ginseng with Sclerotinia libertiana from various 



sources 



Plate XXVIII, figures i and 2, is reproduced from photographs of 

 ginseng roots from two of the above series. Figure i shows a root 

 inoculated with Sclerotinia libertiana isolated from lettuce. Figure 2 

 shows three roots (on the left) inoculated with a species of Sclerotinia 

 isolated from ginseng. 



Reisolations were made from the inoculations of July 15 and the 

 fungus was again grown in pure culture. Inoculations made with the 

 reisolated culture gave positive results. 



Infection was evident in from three to seven days after inoculation. 

 The root at the point of inoculation becomes soft and the rot spreads 

 gradually in all directions, causing the entire root to beame soft and 

 doughy. After the mycelium has penetrated throughout the tissues of 

 the root, it forms tufts of cottony-white felt, in which large black scle- 

 rotia rapidly develop. Sclerotia on the outside of the root have in some 

 cases developed within 10 days after the inoculations were made. When 

 the inoculations are made near the crown of the root, the mycelium 

 spreads to the stem, where it develops similar sclerotia on both the 

 inside and the outside of the stem. The rapidity with which the disease 

 progresses in the inoculted roots depends upon moisture conditions. 



