DISEASES OF GINSENG. Y3 



the parts of the plant above ground are thoroughly coated, further 

 applications are neither necessary nor desirable. Bordeaux does 

 not wash off to any extent. The development of the berries after 

 blossoming exposes new surface, not covered by earlier applica- 

 tions, and special spraying of the seed heads to prevent blasting 

 and shelling of the berries is desirable. Since the first infections 

 occur on the stems, it is desirable to spray very frequently when 

 the plants are coming through and expanding. The fact that the 

 plants in a given bed do not all come through at the same time 

 makes frequent sprayings at this time highly desirable. 



4. Spraying should be done just before rain periods, not 

 after. The spores of the Alternaria fungus germinate only in 

 water, and some hours of continuous moist cloudy weather are 

 necessary for the formation and entrance of the germ-tube of the 

 spores into the tissues of the ginseng plant. Local showers of 

 short duration followed, as they usually are, by bright, sunny 

 weather with brisk breezes, cut very little figure in infections. 

 It is the continuous rains with cloudy sky that is important. These 

 periods are quite accurately foretold by the U- S. Weather Bureau 

 several days in advance. Every grower should be able to inter- 

 pret the weather map and should consult it regularly, making his 

 sprayings just ahead of these periods of rain and cloudy weather. 

 The fungicide must be present on the plants when the conditions 

 favorable to the germination of the spores arrive. Once the fun- 

 gus has established itself within the tissues of the ginseng plant, 

 the bordeaux, or any other fungicide applied, cannot reach and 

 destroy it, hence the futility of spraying after the rain. The im- 

 portance of spraying at the ri^ht time is seldom considered by 

 the grower, or is at least greatly over-shadowed in his mind by 

 such considerations as streught of the mixture, number of appli- 

 cations, or thoroughness. While these are all important factors, 



