542 
Journal of Agricultural Research voi. xxvrn, No s 
Table I. —Results of inoculating Berberis vulgaris and various grasses and cereals 
at University Farm, St. Paul, Minn., with Puccinia graminis poae, from Poa 
compressa collected near Pontiac, Mich., in 1922 a 
Original inocu¬ 
lum 
Species and varieties inoculated— 
March 21,1923 
April 26, 1923 
May 18, 1923 
June 5, 1923 
Teliospores from 
Poa compressa. 
Berberis vul¬ 
garis 4— 
Poa annua.. 0 
I P.compressa !— 
I P. nemoralis 0 
I P. pratensis. 4 
LP. triflora... 0 
Poa annua .... 0 
P. compressa .. 4— 
P. nemoralis . 4 
P. pratensis. . 4 
P. triflora .0 
Avena sativa (Victory, 
Minn. 514) k _0 
Hordeum vulgare (Man¬ 
churia, Minn. 105)_0 
Secale cereale (Rosen, 
Minn. 82).0 
Triticum compactum 
_ (Little Club, C.1.4066)- 0 
~Poa compressa... !4 
Agrostis alba _0 
Dactylis glom- * 
erata . r 0 
Secale cereale ( Ro- 
_ sen, Minn., 82). 0 
• The sequence of inoculations in Tables I and II is indicated by dashes, proceeding from left to right. 
All of the hosts in the same vertical column were inoculated with spores from the host immediately pre¬ 
ceding the dashes. The degree of infection is indicated after each plant inoculated: 0=*no infection; 
1=extremely light infection; 3=moderate infection; 4=very heavy infection. The date above each 
vertical column is that on which the inoculations were made. 
b Accession numbers of Minnesota Agricultural Experiment Station, and Office of Cereal Investiga¬ 
tions, Bureau of Plant Industry, U. S. Department of Agriculture, respectively. 
Table II. —Results of inoculating Poa spp., Phleum pratense, and cereals with 
urediniospores of Puccinia graminis poae from Poa compressa collected near 
Pontiac , Mich., in 1923 
Original inocu¬ 
Species and varieties inoculated— 
lum 
August 23, 1923 
September 6,1923 
September 28,1923 
October 18,1923 
Urediniospores 
Poa annua _3 
~ Poa compressa 4— 
“Poa compressa _4— 
r Poa compressa . 3 
from Poa com¬ 
P compressa 3— 
Avena sativa (Vic¬ 
L P. pratensis _4 
pressa. 
P. fertilis .3 
P. nemoralis.. 3 
P. triflora _3 
Avena sativa 
(Victory, 
Minn. 514).. 0 
Phleum pra¬ 
tense .0 
Triticum com¬ 
pactum (Lit¬ 
tle Club, C.I. 
_ 4066) •.0 
_P. pratensis . 4— 
tory, Minn. 514)«_ 0 
Hordeum vulgare 
(Manchuria, Minn. 
105)..1 
Phleum pratense _0 
Secale cereale (Rosen, 
Minn. 82)_0 
Triticum compactum 
(Little Club, C. 
_ I. 4066).0 
Poa compressa .4 
L Phleum pratense . 0 
• Accession numbers of Minnesota Agricultural Experiment Station, and Office of Cereal Investiga¬ 
tions, Bureau of Plant Industry, U. S. Department of Agriculture, respectively. 
It will be seen from Tables I and II that Poa annua L., P. compressa L., P. 
fertilis Host, P. nemoralis L., P. pratensis L., and P. triflora Gilib. are sus¬ 
ceptible to the rust. Very heavy infection always resulted from inoculating 
P. compressa. While the infection on the other species of Poa was normal, it 
was not so heavy as that on P. compressa. Agrostis albaJL., Dactylis glomerata L., 
and Phleum pratense L. did not become infected, so the rust could not have been 
either P. graminis agrostis or P. graminis phleipratensis. In addition, the fact 
that Berberis vulgaris was very susceptible also excluded the possibility of the 
rust being P. graminis phleipratensis. As wheat, oats, and rye apparently are 
immune, and barley nearly so, the rust could not be the tritici, the avenae or the 
secalis variety. It therefore must be P. graminis poae. 
