72 DISEASES OF GINSENG. 



parasite. The addition of paris green is not necessary. Arsenate 

 of lead may be of some value in increasing- the sticking qualities 

 of the bordeaux, though this also is of very doubtful efBciency. 

 Commercial bordeaux's such as Pyrox etc., are doubtless effective 

 when properly applied, but are usually rather expensive. 



2. The fungicide must not cause burning of the plants 

 when thoroughly applied at the effective dilution. Lime-sulphur, 

 now so generally used as a substitute for bordeaux, appears to be 

 dangerous to ginseng where applied at a strength sufficient to kill 

 the spores of the fungus. Further experiments may discover 

 some modilication of this fungicide which will make it safe at 

 effective strenghts. Burning not infrequently occurs from impro- 

 perly made bordeaux or the use of copper sulphate solutions alone, 

 without tlie addition of lime. Failure to stir the lime milk 

 thoroughly before mixing with the copper sulphate solution, the 

 use of poor or air slaked lime, or tiie use of copperas (iron sulphate) 

 instead of blue vitrol (copper sulphate) are among the sources of 

 error in preparing bordeaux. The danger from the use of too 

 little lime may easily be eliminated by testing the mixture with a 

 few drops of a saturated solution of potassium ferro-cyanide. 

 This turns dark brown if not enough lime has been added to the 

 copper sulphate solution. No matter how much copper sulphate is 

 used, no injury to the plants will result if enough lime is added to 

 neutralize it. A 10-10-50 mixture may be safely applied, but it 

 is entirely unnecessary, since a 3-3-50 has been shown to entirely 

 prevent the germination of the Alternaria spores. 



3. The fungicide must be thoroughly applied. All parts 

 of the plant susceptible to infection, stems, leaves, and seed heads, 

 must be covered and kept so. Thoroughness of application is far 

 more important than the strenght of the mixture. Once all of 



