64 ROSES 



to the leaf blight previously mentioned but 

 rarely met with is the leaf spot, due to the 

 fungus Cercospora rosaecola. This produces 

 spots that are of a grey colour with a dark pur- 

 ple border, and the spores are long and borne 

 in little tufts upon the surface of the central 

 portion of the dead areas. 



As yet this leaf spot is not common, but 

 when found at all is often quite destructive. 

 As the spot fungus produces its spores on the 

 outside of the plant, it is easily controlled by 

 fungicides. 



Black Speck on Roses. Closely associated 

 with fungous diseases of the rose, and generally 

 regarded as such is the black speck. Little 

 round, black dots about the size of a pin's 

 head are seen scattered irregularly on the 

 (generally lower) surface of the leaves or on 

 the stem, label or stake near the plant. 



This trouble is due to the indirect, and not 

 the intentional action of a fungus, and in this 

 respect is quite unusual and merits a word 

 of consideration. The fungus that is the 

 source of trouble is one of the moulds and 

 grows upon organic substances and not upon 

 the rose. 



It forms in large numbers upon the manure 



