OUTDOOR ROSE GROWING 



Black spot is another disease which sometimes 

 comes towards the end of the summer. It is experi- 

 enced mostly in potted greenhouse plants. If only 

 dormant field-grown stock is used the disease is 

 not so prevalent. Dr. Huey concurs in this opinion 

 and, as a cure, advocates picking off and burning 

 affected leaves as soon as they appear. Last year a 

 formaldehyde solution was used with fair success, 

 but black spot is most difficult to eradicate. 



The "American Florist," hi its issue of June 14, 

 1914, has a very interesting article on black spot 

 treatment, taken from publications of the National 

 Rose Society of England. The main point in the 

 article is that black spot is a fungous disease which 

 invades the living tissues of the plant and there 

 reproduces itself by means of spores on the leaves. 

 To combat the disease formaldehyde is suggested 

 and is supposed to be absorbed by the tissues of 

 the plant and to kill the spores on the leaves. This 

 article further states that it is considered advisable 

 to use the formaldehyde as a spray, not only on the 

 leaves and stems, but also to have the solution reach 

 the plant through the soil. To accomplish this result 

 it is advised that "the cool of a calm evening in 

 summer when the soil had been previously loosened, 

 and moistened if necessary, would be ideal." In 

 the treatment referred to above it is necessary, in 



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