DISEASES OF GINSENG. 87 



2. Practice the sunshine disinfection. During hot mid- 

 summer cultivate the ground many times and try to kill all 

 bacteria. 



3. Drain the soil thoroughly and keep from getting soggy. 

 ■i. Fertilize with 600 to 700 pounds of calcium nitrate per 



acre, or use ashes or phosphoric acid fertilizers. 



Crown Rot. 

 (sclerotinia libertina fuckel.) 



This rot has never been found very abundantly on ginseng, 

 but yet it is widely spread and common on other plants. The 

 fungus causing the disease seems to gain entrance to the plant 

 through tlie lower part or base of the stem, near the surface of 

 the ground. It works slowly up the stem but quite rapidly down, 

 soon entering and rotting the root. The stem is bleached and the 

 tissues become sunken and rotted. At this stage the stem is weak 

 and the top falls over. The tissues of the diseased crown of tlie 

 root becomes soft and "doughy", so tliat it is like bread dough, 

 but more watery. The diseased root is tough, but is non-elastic 

 The mycelium or roots of the fungus (Sclerotinia) are abundant 

 running between the cells of the root. This mycelium grows out 

 through the lenticels in the root and forms bunches or tufts of 

 white felt. Large Sclerotia or hard compact lumps of mycelium, 

 are also formed (Fig. 37) on the outside of the root. These sclero- 

 tia are at first light colored or quite white. They become darker, 

 changing to a brown and finally black, being folded or wrinkled 

 very large and hard. In the spring these sclerotia germinate and 

 send up a cup shaped body which bears the spring spores. 



This disease has also been observed to attack the upper 

 part of the plant. In these plants leaflets all drooped from the 

 petioles being practically rotted off and the leaves were wilted. 



