RESISTANCE IN RYE TO LEAF RUST, PUCCINIA DIS- 
PERSA ERIKSS . 1 
By B. B. Mains, Associate Botanist, Purdue University Agricultural Experiment 
Station, and Agent, Office of Cereal Investigations, Bureau of Plant Industry, United 
States Department of Agriculture, and C. E. LEighty, Agronomist in Charge of 
Eastern Wheat Investigations, Office of Cereal Investigations , Bureau of Plant Industry, 
United States Department of Agriculture 2 
INTRODUCTION 
The leaf rust of rye, Puccinia dispersa Erikss., and its host are coex¬ 
tensive, for this disease has been found practically in all parts of the 
world where rye is grown. The literature on this rust refers to it under 
several different names. It belongs to that group of leaf rusts of cereals 
and wild grasses to which the name P. rubigo-vera (D C.) Wint. was for a 
long time applied. Eriksson and Henning (p) 3 separated this species 
into two, P. glumarum (Schm.) Erikss. & Henn., the stripe rust, and 
P. dispersa Erikss., the brown rust of cereals and wild grasses. On 
account of differences in hosts, a number of races were recognized within 
the brown rust by Eriksson (6), that on rye being designated as P. 
dispersa f. sp. secalis. Later the races on the other cereals and the 
wild grasses were raised to specific rank by Eriksson (7) and given 
binomial names, leaving the name P. dispersa for the rust found on 
rye. As such it has been most widely known in the literature which 
deals with this fungus as the cause of a disease of rye. Still other names, 
however, have been applied to it in mycological literature, such as P. 
secalina Grove, P. asperifolii (Pers.) Wettst., and Dicaeoma asperifolii 
(Pers.) Kuntze. A full list of such names is given by Arthur and 
Fromme (1) in the North American Flora. 
The biology of this rust has been more or less completely worked out. 
Puccinia dispersa was shown by DeBary (2) to produce its aecia on 
Anchusa officinalis and A . arvensis, results which were duplicated by a 
number of others both in Europe and in this country. Apparently, 
however, this aecial stage usually is not necessary for the survival of 
the rust from year to year, since it has been observed to live over winter 
in the rye plant itself by BaudyS (5), Treboux (13), and others in Europe 
and by Carleton (4), Christman (5), and others in this country. That 
the other cereals and the wild grasses play no part in the overwintering 
and spread of this disease of rye is evident from the work of Eriksson 
(6, 7) and others, who have found that this rust is closely restricted to 
rye. 
The severity of the disease varies in different regions, according to 
climatic conditions. Its severity also varies from year to year in any 
one locality as weather conditions vary, but it is always present to some 
extent. Under favorable conditions, such as years with mild winters and 
1 Accepted for publication May 2, 1923. Published with the approval of the Director as a contribution 
from the Department of Botany, Purdue University Agricultural Experiment Station. Cooperative 
investigation between the Purdue University Agricultural Experiment Station and the Office of Cereal 
Investigations, Bureau of Plant Industry, United States Department of Agriculture. 
a The writers wish to acknowledge the efficient assistance of Mr. Leroy E. Compton, Junior Pathologist, 
Office of Cereal Investigations, in the laborious task of inoculating seedlings. 
• Reference is made by number (italic) to “Literature cited,” p. 251-352. 
Journal of Agricultural Research, 
Washington, D. C. 
afu 
(243) 
Vol. XXV, No. 5 
Aug. 4, 1923 
Key No. G-323 
