DISEASES OF ROSES 95 



kerosene stove or other means of heating the sulfur being neces- 

 sary at times when the houses are not artificially heated. The use 

 of the sulfur-lead dust on roses under glass will undoubtedly control 

 the disease and may in many cases be a more desirable method 

 than that of using evaporated sulfur. 



Crown-Canker. 



An important disease of the rose, to which the name crown- 

 canker has been given, was first observed by the writer (13) in 

 September, 1916, affecting American Beauty plants. The grower 

 stated that he had had the disease under observation during the 

 past four or five years, a few plants being affected each year and 

 the disease being confined to a single house. 



Subsequently plants affected with the crown-canker disease have 

 been received from eight growers, the states of Missouri, Penn- 

 sylvania, Indiana, Michigan, Massachusetts, and New York being 

 represented. A Missouri grower observed the disease in 1916 on 

 the varieties Hoosier Beauty and Ophelia growing on their own 

 roots. An eastern grower was of the opinion in 1916 that all of 

 his many thousands of plants were affected, and it is the opinion 

 of the T;vTiter, after having examined his plants, that at least a very 

 large percentage of them were diseased. During the four years 

 prior to 1916 increasingly poor results were obtained by this grower 

 who when interviewed in November, 1916 was planning to destroy 

 his plants, sterilize houses and soil, and begin anew with healthy 

 stock. 



Rose plants of the varieties Hoosier Beauty, Ophelia, Hadley, 

 Mrs. Charles Russell, Sunburst, American Beauty, and many 

 seedlings have been observed affected with the disease. Both 

 grafted plants and those growing on their own roots are affected. 

 It is questionable whether or not any variety is immune. Indica- 

 tions are that this may prove to be the most important disease of 

 roses grown under glass. To date no record has been made of this 

 disease on out-of-doors plants. 



Symptoms. Diseased plants are affected at the crown, usually 

 just at the surface of the soil, the lesion in advanced cases frequently 



