4I 6 1 I XGOUS DISKASKS OF PLANTS 



XVI. BROWN RUST OF WHEAT AND RYE 

 ruhigo-ve.ra De C. 



ERIKSSON, J. Ueber die Specialisirung des Parasitismus bei den Getreiderost- 



pilzen. Ber. d. deut. bot. Ges. 12 : 292-331. 1894. 

 FRKKMAX, E. M. Experiments on the Brown Rust of Bromes (Puccinia dis- 



persa). Ann. Bot. 16: 487-494. 1902. 

 WARD, H. M. On the Relations between Host and Parasite in the Bromes 



[etc.]. Ann. Bot. 16: 233-315. 1902. 



Occurrence and nomenclature. The brown rust of wheat and 

 rye is second only to the black rust in economic importance. In 

 consideration of the detailed account of the black rust of wheat 

 and other cereals and grasses, it will only be necessary in discuss- 

 ing the brown rust to draw attention to the chief points of interest 

 by way of comparison. Puccinia rubigo-vera occurs upon a variety 

 of grasses besides wheats and rye, among these certain species of 

 Bromus, Lolium, and Elymus. The secidial stage was by De Bary 

 determined to be a form on a borage, Anchusa arvensis, known 

 to occur also on AncJiusa officinalis . The nomenclature of this 

 rust is complex, and at the outset it may be said that Eriksson 

 and Henning distinguish under the above name two species, and 

 they have abandoned the name Puccinia rubigo-vera De C. One 

 of these species is denoted the yellow rust, and to it is applied an 

 old name, Puccinia glumarum (Schm.). The other species, desig- 

 nated brown rust, is made a new species and called Puccinia dis- 

 persa. The last named is found by inoculation to be connected 

 with the aecidium on the borage hosts, while Puccinia glumarum 

 is without known aecidial stage. 



At any rate, these forms have not been commonly distinguished 

 in the literature, and Puccinia rubigo-vera has been reported 

 almost as widespread throughout the region of cereal production 

 as the black rust. In the United States it is often unusually abun- 

 dant in the central West. Bolley and others have shown that this 

 fungus is able to carry itself through the winter, by means of more 

 or less continuous production of the uredo stage and by the my- 

 celium in the leaves of winter grain. 



The aecidia occur upon leaf blades, petioles, stems, and calyx of 

 the borage hosts, producing rather conspicuous, bright yellow, 

 slightly swollen spots. 



