174 PRACTICAL FLORICULTURE. 



by a sudden lowering of temperature, accompanied by a 

 damp atmosphere, so that the injury to roots and leaves 

 may be simultaneous in this case. But we also know that 

 it occurs in hot and dry weather, where there has been no 

 sudden change of temperature, which would indicate, in 

 this case, that it was caused solely by the injury to the 

 tender roots by long continued drouth. In any case, 

 whatever be the cause, it is the only safe plan to avoid, as 

 far as possible, extremes of temperature and moisture. 

 In the summer of 1880 we had about a thousand very 

 fine plants of American Beauty Hose (one of the most 

 liable to be attacked with Black Spot), growing in the 

 open air in eight-inch pots splendid plants, without 

 speck or blemish. About the middle of July, half of 

 the plants were taken into the rose house, where they 

 kept in splendid condition all fall and winter, while the 

 other half was left outside ; both lots looked equally 

 well until near the end of August, when the lot left out- 

 side began to show indications of the Black Spot, and 

 although they were removed under cover of the green- 

 house at once, they never recovered, and were almost a 

 total loss. A lot of the Bennett Roses left out at the 

 same time were also so affected by the Spot as to destroy 

 them. The conclusion arrived at was that the lot left 

 out in the open air had undergone some quick lowering 

 of temperature sufficient to chill the leaves and roots of 

 the plants. The remedy, then, is to get them under 

 cover, where they can be controlled, in time to prevent 

 such contingencies. 



There is still another disease, which, however, is less 

 common than the Black Spot or Mildew, that affects Eoses 

 when grown under glass ; it is called Club Root, Knot 

 Root, or Wart Root. The indications that this trouble is 

 at the roots are given by the young shoots of the Roses 

 getting light in color, and occasionally, if the roots are 

 badly affected, the leaves assume an appearance of being 



