80 DISEASES OF GINSENG. 



by which it may be controlled. Sterilization of the soil by the 

 use of formalin or steam is sometimes practiced, Ijut it is a ques- 

 tion whether this is always advisable, for it desti'oys a large num- 

 ber of oi'ganisms which are of great importance in maintain- 

 ing soil fertility. 



In this paper all the material available on the root diseases 

 of ginseng has l)een reviewed, and the principal facts concerning 

 each brought together. I am especially indebted to Prof. H. H. 

 Whetzel for the use of his private notes which he has collected 

 during his connection with the ginseng disease work. 



The Wilt, 

 (acrostalagmus panax rankin.) 



The wilt disease has been known as a common ginseng root 

 malady for several years. It makes its greatest inroads in the 

 spring, esj)ecially in June. The first indication of this disease of 

 ginseng is evidenced by a dropping of the tips of the leaflets. 

 The leaflets then gradually lower until, when completely wilted, 

 the leaves hang limp (Fig. 29) and the top of the leaf stalk bends 

 over. Plants showing these symptoms may not be attacked by the 

 "wilt disease," however, for any cause which would produce a 

 wilting might be confounded with it. 



If, however, the root l^e dug up and cut across, those which 

 are affected with the wilt will show a definite reddish brown ring 

 (Fig. oO) .just inside the Ijai'k of the root. This brown ring indi- 

 cates the diseased tissue of the root and shows us the seat of the 

 trouble. Normally the root should be perfectly white throughout. 



If we take a section of this affected root and examine it under 

 the microscope (Fig. 31), we will find that the region of the root 

 which is l:)rown is made up of l:)undles of sap tubes. These tubes 

 extend fi'om the very small roots up through the root stalk and 



