UROMYCES 



293 



Haricot bean rust. Haricot beans or 'scarlet-runners' are 

 often attacked by Uromyces appendiculatus (Link.) causing 

 the leaves to fall early, when the development of pods is 

 checked. Aecidia, uredo, and teleutospore stages all follow 

 in succession, forming numerous minute brown pustules on 

 the leaves. 



Aecidiospores angularly globose, whitish, slightly punctulate, 

 1 7-3 2 x 14-20 p. Uredospores pale brown, aculeolate, 24-33 X 

 16-20 /*. Teleutospores elliptical or subglobose, smooth, 



FIG. 85. Uromyces colchici. i, portion of a diseased 

 Colchicum leaf; 2, teleutospores, one of which has 

 germinated and produced a promycelium bearing three 

 secondary spores. Fig. i reduced, Fig. 2 mag. 



dark brown, apex much thickened, with a small, hyaline, wart- 

 like papilla, 26-35 x 20-26 /*. 



If the disease appears early, spray with Bordeaux mixture ; 

 when the pods are formed, use permanganate of potash. 



Broad bean rust (Uromyces fabae, De Bary) is a parasite 

 very common on the leaves and stems of broad beans, peas, 

 also on various wild leguminous plants, vetches, etc. The 

 aecidium stage appears in the spring; the cluster-cups are 

 grouped on conspicuous, thickened, whitish spots on the stem 

 and leaves. The uredo stage follows as minute brown 

 pustules, usually scattered thickly over the under surface of 



