176 



THE CANADIAN HORTICULTURIST 



July, 1914 



Specific Diseases of Ginseiig 



Prol. J. £. Howitt 



AVERY common and very wide- 

 spread disease of ginseng is the 

 alternaria blight. It is found in 

 nearly every ginseng garden, and once 

 the causal fungus becomes established 

 its eradication is almost impossible. 

 This disease attacks all parts of the 

 plant above ground. The first indica- 

 tions of the disease are dark brown 

 spots on the stems ; later spots appear 

 upon the leaves. These are half an inch 

 or more in diameter, and in the early 

 stage have a water soaked appearance, 

 but later become dry and papery, with 

 broad, rusty-brown margins. Very often 

 these spots run into each other and the 

 whole leaf becomes involved and withers. 

 The stems often rot and fall over. If 

 the diseased stems are examined, upon 

 the surface will be noticed a velvety 

 brown coating due to the presence of 

 immense numbers of fungus spores. 



EEADTCATING THE ]>TSEASE 



Sanitary measures, such as the re- 

 moval and the destruction of the dis- 

 eased tops, the burning over of the beds 

 in the autumn or the spraying of the 

 surface with a strong copper sulphate 

 solution (one pound of copper sulphate 

 to five or ten gallons of water) will do 

 much to hold this disease in check, but 

 cannot be relied upon to. prevent loss 

 when conditions favorable to the de- 

 velopment of the fungus occur. Pro- 

 tecting plants from infection by the 

 Alternaria Fungus by spraying them 

 with some good fungicide is the only 

 sure way of preventing loss. Growers 

 differ in their opinion as to what is the 

 best fungicide for spraying ginseng. In 

 the United States Bordeaux mixture has 

 been found to give good results. Pyrox, 

 which is a combined fungicide and in- 

 secticide, being constituted largely of 

 Bordeaux and lead arsenate mixed to- 

 gether, has been found by some growers 

 to give better results than Bordeaux 

 mixture. Mr. Peter Menzies,'the vete- 

 ran ginseng grower, claims to have had 

 good results by spraying with lime- 

 sulphur of the strength of one gallon to 

 forty gallons of water. Whatever fun- 

 gicide is used, the success obtained will 

 largely depend upon its thorough and 

 timely application. The time to spray 

 to prevent Alternaria Blight is just be- 

 fore a rain and not just after a rain as 

 many growers seem to think. The fun- 

 gus which causes the blight only gains 

 entrance to the plants during rainy and 

 cloudy weather when the plants are sat- 

 urated with moisture, and thais it is 

 important if infection is to be prevented 

 to have the plants covered with a fungi- 

 cide at such times. Thorough work can 

 only be done with a nozzle giving a fine 



mist and with a pump which gives a 

 pressure of not less than sixty pounds. 

 I'rofessor Whetzel of Cornell Univer- 

 sity, says: "The most important times 

 at which to spray to prevent Alternaria 

 Blight are just when the plants are com- 

 ing up and expanding; when the leaves 

 are fully expanded ; just before the blos- 

 soms open ; just as the berries begin to 

 enlarge and just before the berries be- 

 gin to color. " 



BUST. FTBRE BOT OR fjND BOT 



Rust or Fibre Rot is a very serious 

 fungus disease of ginseng; it sometimes 

 causes more loss than the Alternaria 

 Blight. The symptoms of this disease 

 vary very much with the age of the 

 plants and the character of the weather. 

 In seedlings the most noticeable symp- 

 toms during a dry season are the grad- 

 ual change in the color of the leaves from 

 dark healthy green to a sickly light 

 green, followed by a premature coloring 

 in shades of red and yellow. Later, the 

 leaflets wither and the stems wilt. In 

 damp weather the color changes are not 

 so marked and wilting is more sudden, 

 the seedlings toppling over and the tops 

 remaining green. If the roots of the 

 diseased seedlings are examined, the 

 fibres will be found to be brown and 

 rotted. Very often all the fibres of a 

 root will be completely destroyed, giving 

 the root a trimmed up appearance. On 

 the larger roots rust spots are noticed, 

 and frequently pocks and scars. These 

 are often superficial, but sometimes ex- 

 tend deep into the flesh of the roots. 



Applications of acid phosphate at the 

 rate of from one thousand to two thou- 

 sand pounds per acre are recommended 

 for the control of this disease. Acid 

 phosphate is now quite extensively used 

 by the ginseng growers in the United 

 States and has been found by many to 

 greatly reduce the amount of rust. Ster- 

 ilization of the soil with steam or for- 

 malin is recommended for seedling beds 

 or for old beds that are to be reset. 



Phytophthora Mildew is a fungus dis- 

 ease which up to the present time has 

 not troubled ginseng growers in Ontario, 

 but as it has proved quite troublesome 

 to Michigan growers it is advisable that 

 a careful watch should be kept for it. 

 The symptoms of this disease are very 

 likely to be confused with the symptoms 

 of Alternaria Blight. The most common 

 symptom is the drooping of the leaflets 

 of one of the leaves down around the 

 petiole. Another noticeable symptom is 

 the killing of the basis of the leaf 

 stalks where they join the stem, causing 

 the leaves to droop and die along the 

 stem. But these symptoms are also 

 characteristic of Alternaria Blight, but 

 in the case of this disease the dead stems 

 are covered by a brown velvety covering 

 of spores, wrile stems attacked by mil- 

 dew show in the early stages an almost 

 indiscernible silvery-white coating due 

 to the presence of the spores of the 

 causal organism. This coating, how- 

 ever, soon disappears and the diseased 

 parts become soft and slimy especially 

 in damp weather. Spots similar to 



those of Alternaria Blight are produc- 

 ed upon the leaves. In the early stage 

 they are dark green and water-soaked, 

 but soon the centre of the spot becomes 

 white, the margins remaining dark 

 gren and water-soaked. In damp wea- 

 ther the disease spreads down the stem 

 and causs the root to rot. 



Diseased seedlings should be removed 

 from the beds as soon as they are notic- 

 ed. Give a thorough spraying with Bor- 

 deaux mixture early in the spring while 

 the plants are coming up. 



DAMPING OFF OF SEEDLINGS 



"Damping Off" is another fungus 

 disease which very frequently destroys 

 seedlings, especially in wet seasons, and 

 in ginseng beds which are not properly 

 underdrained. The fungus rots the stem 

 just at the surface of the soil and the 

 tops drop off. The symptoms are so 

 characteristic that the disease is familiar 

 to nearly every ginseng grower. 



Professor Whetzel recommends the 



