6 BULLETIN 1046, U. S. DEPARTMENT OF AGRICULTURE. n 
In 1914 only two urediniospore sprays were applied, one on April 
19 and the other on May 23. Neither of these sprays was followed 
by any noticeable rust infection. Canvas covers were not used. In 
1915 urediniospore sprays were given on April 20, 21, 27, and 29, 
and on May 7, 10, 20, 22, and 31. Inoculated seedlings were trans- 
planted into the soil in vacant rows, which were left for that purpose, 
this being the first attempt to use the infection-center method. 
Canvas covers were used and a severe epidemic was caused, as shown 
by the data on rust infection. In 1916 urediniospore sprays were 
given on April 6, 13, 14, 20, 25, 26, and 29, and on May 1, 4, 16, 19, 
and 27. Canvas covers were used. In addition to these sprays the 
intection-center method was employed. A severe epidemic resulted. 
In 1917 sprays of urediniospores were given on May 23 and 29, and 
on June 6. A few hand inoculations in the field were made in the 
spring, but the efforts were mostly directed toward establishing in- 
A,5percent. 8B, 10 ner cent. C,25 percent. D,40 percent. E,65per cent. F, 100 per cent. 
Fic. 1.—Scale for estimating rust, illustrating six degrees of rustiness used in estimating the percentage of 
stem-rust infection. The shaded spots represent rust, and the figures represent approximately the rust 
percentages computed on the basis of the maximum of surfaces covered by rust as Shown in the 100 
per cent figure (F). Figure F in the diagram represents 37 per cent of actual rust-covered Surface and 
is arbitrarily selected as 100 per cent. The other percentages are in terms of figure F. 
fection centers. It was evident from the results obtained that the 
latter method was sufficiently dependable to warrant the discontinu- — 
ance of urediniospore sprays. 3 
The common barberry (Berberis vulgaris L.; see Pl. I, fig. 2), planted 
south of the rust nursery plats, furnished some ecial infection in 
1915, 1916, and 1917. Straw, bearing telia of stem rust, was placed 
around each shrub in the fall, so as to provide the necessary telio- 
spore material to infect the barberry leaves in the spring. 
The final field notes were taken during the latter part of June or 
early in July, at the time the nursery was harvested. These included 
the percentage of stem rust, estimated in accordance with the scale 
shown in figure 1 and used by the Office of Cereal Investigations of 
the Bureau of Plant Industry, United States Department of Agri- 
culture. Notes on the type of head, plumpness of grain, and other 
characters also were recorded. 
