THE EOSE PHKAGMIDIUM 



117 



The Rose Phragmidium 



Phragmidiiim speciosum 



The peculiar appearance of this disease when attack- 

 ing tlie stems of ro'^ei is well illustrated in Fig. 52 a. 



bark of such 



l.ie 



Vfffi 



stems is more or less 

 covered with irregu- 

 lar black patches, con- 

 sisting of vast num- 

 bers of the winter 

 spores of the fungus, 

 borne upon long slen- 

 der stalks, as seen, 

 much magnified, at h. 

 The spores themselves 

 are divided by trans- 

 verse partitions into 

 from five to seven 

 cells. The mycelium 

 of this fungus devel- 

 ops in the inner bark 

 and the cambium 

 layer of the stems, 

 but is believed not to 

 penetrate into the 

 woody tissue. Of 

 course it interferes 

 with the flow of sap, 

 and when, as often 

 a b hap])ens, it extends 



FIG. 52. ROSE PHKAGMiDiuM. clcar arouud the stem, 



a, Affected stem; 6, winter spores. it may JOrOVO fatal to 



the plant. The mycelium is perennial in the stems, 

 living from one season till the next, so that when once 

 infested there is no way of ridding a plant of it. The 



