INFECTION EXPERIMENTS WITH TIMOTHY RUST 
By E. C. Stakman, Head of the Section of Plant Pathology and Bacteriology , and 
Louise Jensen, Mycologist , Division of Botany and Plant Pathology, Department 
of Agriculture , University of Minnesota 
INTRODUCTION 
There is some diversity of opinion as to whether or not timothy rust 
should be regarded as a distinct species. Eriksson and Henning (2, p. 
140-142) 1 in 1894 designated it il Puccinia phleipratensis Eriks, u. Henn. ” 
Johnson (4) decided that timothy rust in this country was the same as 
that in Sweden and favors giving the fungus specific rank. Kern (5, 6), 
on the other hand, thinks it should be considered as a physiological 
species, or, at most, a variety or subspecies. 
It is therefore of interest to know the infection capabilities of the rust. 
Eriksson and Henning (3, p. 136-141), reported the successful infection of 
rye ( Secale cereale ) and oats (Avena sativa) , but none of wheat ( Triticum 
vulgare) or barley (Hordeum vulgare). Johnson (4, p. 9) obtained results 
confirming those of Eriksson and Henning. Johnson also succeeded in 
successfully infecting a number of grasses. He found that the rust would 
not transfer directly to barley, but if transferred first to oats and then to 
barley infection resulted. In the same way Dactylis glomerata acted as a 
bridging form between timothy and wheat. Mercer (7) was unable to 
obtain successful infection on wheat, rye, and various grasses as a result 
of inoculations made with timothy-rust urediniospores. 
The inoculations made by the writers were all on seedlings. The leaves 
were first thoroughly moistened either with an atomizer or by rubbing 
water on with the fingers. The spores were applied with a flat inoculating 
needle. The plants were then placed in shallow pans of water and kept 
covered with bell jars for 48 hours. The grass seeds were obtained from 
the Minnesota Seed Laboratory. The following varieties of cereals were 
used: Oats, Improved Ligowa, Minn. No. 281; barley, Manchuria, Minn. 
No. 105; wheat, Bluestem, Minn. No. 169; rye, Swedish, Minn. No. 2. 
RESULTS OF INOCULATIONS 
The writers made a number of inoculations with timothy-rust uredini¬ 
ospores, the results of which are given in Table I. 
1 Reference is made by number to “ Literature cited,” p, 216. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
an 
(211) 
Vol. V, No. s 
Nov. 1,1915 
Minn.—6 
