ORAKGE RUST OF BLACKBERRIES 



101 



The most extended account of this disease is pub- 

 lished in the 1887 Report of the Department of Agri- 

 culture (pp. 357-3G1). 



The Orange Rust 



Cceoma nitens 



The orange rust, or red rust, of blackberries, is fa- 

 miliar to most growers of small fruits. The disease 

 becomes noticeable as soon as the foliage expands in 



FIG. 47. ORANGE RUST. 



a, Under surface of Ijlackberry leaf showiuLf si)ots of pecidium sta^e; 6, same of 

 raspberry leaf showing both secidium and Puccinia spots. 



spring, aifected leaves having a peculiar golden color, 

 which at once distinguishes them. A little later the 

 surface becomes more or less covered with small round 

 patches of orange-colored spores, to which the common 

 name is due. The life-history of the fungus has only 

 recently been definitely worked out. 



The fungus exists on the blackberry plant in two 

 very different stages. The orange spores that are devel- 

 oped in spring and early summer, as shown in Fig. 48, 

 belong to the CBcidium stage. They germinate on the 



