6o8 
Journal of Agricultural Research 
Vol. XXIV, No. 7 
times on the ordinary autumn-sown crop even in the depths of winter. The twisted 
leaves lying on the soil form a series of sheltered moist chambers on the inner surface 
of which the rust pustules are occasionally present in great numbers. These may 
develop with great rapidity in the early spring and at times as early as March the 
whole of the plant’s foliage may be yellow with the rust. The winter’s cold does not 
appear to injure these spores for they germinate readily when brought into the labo¬ 
ratory. 
Hecke (4) concludes that P. glumarum can overwinter in Austria. 
He has observed the disease breaking out in the spring upon the old 
spots on the leaves which had been infected in the preceding autumn. 
In about two weeks this would be followed by a second generation 
appearing on the new growth of the plants. He concludes that the con¬ 
ditions necessary for an epidemic of yellow rust in any given year are a 
sufficient number of overwintering plants carrying mycelia and meteor¬ 
ological conditions favorable for its development in the spring. 
Eriksson and Henning (5) conclude that P. glumarum may overwinter 
as mycelium in grain seedlings, and that this method is especially signifi¬ 
cant in years when there is a continuous covering of snow on the ground 
throughout the winter. They were doubtful if this means of overwin¬ 
tering is sufficient to carry the rust over from year to year. Henning 
(5) in a recent paper has reviewed the literature upon overwintering of 
this rust in Europe. He finds that the reports from various countries 
in central and northern Europe show that this rust can overwinter, at 
least when the host plants are protected, in the shape of uredinial myce¬ 
lium. Such overwintering has been observed in Sweden by Eriksson, 
Henning, and Klebahn; in Denmark by Rostrup; in Austria by Hecke; 
in Bohemia by Baudys; in Russia by Treboux; and in Germany by 
Kirchner. 
According to the author’s observation there does not appear to be any 
doubt that the uredinial stage of stripe rust in either its urediniospore or 
mycelial condition can survive the winter in the mild climate of the 
coast region of the Pacific Northwest. When the winters are mild, 
it is possible to find fresh uredinia developing in any month from Sep¬ 
tember to July in this region. 
In the autumn of 1917 numerous varieties of wheat were sown at 
Corvallis, Oreg., in order to test them for resistance to stripe rust. A 
guard row of Chul wheat, which is very susceptible to stripe rust, was 
sown around the entire nursery in which these varieties were being 
grown. This entire border row was inoculated on November 21 and 
December 3 with urediniospores of P. glumarum. Infection spread con¬ 
tinuously tlu'oughout the winter until by January 30 infection was quite 
general on all susceptible varieties of wheat adjacent to the inoculated 
plants. By March i, all the susceptible varieties were heavily infected. 
During the winter of 1917-18 a number of pots of the club wheat 
known as Dale (Dale Gloria), which is a susceptible variety, were grown 
in the greenhouse and inoculated with urediniospores of stripe rust until 
they were heavily infected. They were then placed out of doors in an 
exposed place for five weeks of the coldest weather during the winter. 
Snow fell three times during this period, and the plants, which were 6 to 
8 inches tall, were killed down to half their length by the frost. In six 
days after they were again taken into the greeiffiouse they were covered 
with urediniospores on the portions of the leaves which had not been 
killed. 
Observations also show that the fungus can overwinter readily on 
various wild grass hosts. In the fall of 1917 and also in 1918, observa- 
