360 



(hat the fimgns would srow equally well on alkaline and acid media in 

 any strength which could be used on the soil. From this it seems prob- 

 able that changing the acidity of the soil would be of no benefit here, as 

 It is in the case of some other ginseng diseases. Until some other means 

 lor its control is found, it would be advisable to keep a sharp lookout for 

 black roots when digging in the fall, and to examine all spots where plants 

 fail to come up in the spring. If any diseased roots are found, search 

 the area carefully and remove and burn all of them. The .soil in the in- 

 fested area should tlien be sterilized with formalin, diluted 1-100, care 

 being taken not to injure the adjacent healthy roots, or if suitable appa- 

 ratus is at hand, steam sterilization may be used. If the garden becomes 

 too badly infested, the only remedy is to move the seedlings to another 

 garden, carefully sterilizing all tools with formalin or corrosive sublimate 

 before using them in t])e new garden. Van Hook ("04) cites a case where 

 a grower had set roots in a bed from which black roots had been taken 

 six or seven years before. The roots faile<l to come up in the spring, and 

 on being examined were fmnid to be infected with P.lack Kot. thus show- 

 ing that this fungus is appan-ntly capable of remaining in the soil as a 

 saprophyte for several years. 



CROWN HOT. 



This disease has been Known to ginseng growers for several years, 

 but except in a few cases it has not been found very abundant. The first 

 nienti(in of it was by J. II. Koehler ("03)' in a letter to Special Crops. Since 

 then it has been reported fmni various cdunties in .New York and from 

 Slates as far we.st as Wisconsin. 



Tlicrc are two different tyjies of the disease: one in wliidi it attacks 

 llie upper part of the stem, and tlie other in wiiich it attacks the root at 

 or near the crown. In tlio latter type, the organism causing the trouble 

 seems to gain entrance into the plant through the base of the stem near 

 the surface of the ground, or in some cases through the upper part of the 

 root. It works slowly up the stem and quite rapidly down, soon entering 

 and rotting the root. TJie stem loses its green color and the tissue be- 

 comes shrunken, so that the fil^ro-vascular-bundles stand out sharply as 

 long striations or ridges. The stem soon becomes hollow and inside are 

 found lai'ge black si-lcrntia. These are also found <in tin- rnnts. The 

 tissue of tlic (liscascil rout generally becomes soft and '•diMigby."' The 



>('03) Koehler, .7. H. Letter to Editor. Special Croi)s 2 :148. Sept. 100.3. 



