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," in 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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