38 BULLETIN 1276, U. S. DEPARTMENT OF AGRICULTURE 
An infection of 10 per cent or more usually is sufficient to cause a 
noticeable reduction in yield, while 100 per cent infection of black 
stem rust often results in a total failure of the crop. The quality 
of the wheat also is injured by rust. 
Data on stem-rust infection have been obtained during two years 
at each of six stations, or in a total of 12 station years. Stem rust 
was recorded in 1914 at Akron, Colo.; in 1915 at Newell, S. Dak., 
and Archer, Wyo.; in 1916 at Highmore and Newell, S. Dak., and 
Hays, Kans.;in 1919 at Highmore, 8S. Dak.; in 1920 at Akron, Colo., 
aestiche® Wyo.; in 1921 at Dickinson, N. Dak.; and in 1922 at 
Dickinson, N. Dak., and Hays, Kans. Stem rust has not occurred 
at Moccasin, Mont., during the 15 years from 1908 to 1922. 
A, 5 per cent B, 10 per cent C, 25 per cent D, 40 per cent E, 65 per cent F,100 percent 
Fic. 3.—Seale 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 surface 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. 
TABLE 21.—Stem-rust infection of 23 varieties and strains of winter wheat grown 
at six experiment stations in the Great Plains area during three or more years in 
which rust occurred in the 9-year period from 1914 to 1922, inclusive, compared 
with that of the Kharkof variety for the same station years : 
Average stem-rust infection (per cent) 
: Station : : 
Class and variety C.I. No. years ec Kharkof, Difference 
arlety 
same 
named = 
SAEZ Less | Greater 
Hard red winter: 
KEN aT ROL See res eee Se Te Seema Nee 12 GID YL: Bt CRS DORR RGR Beer 
Alberta Red this: t2sat be bee - rene 2979 4 1f.5 iPS! Oh Sait oe) ee 
PAU Tare mags se Se eee ge 5797 3 Wap ¥/ 19.7 4. 0c ss) ee 
NGO Sethe 2 RNP Pa) eee ETE 1438 6 15.0 IB SES Sees 2 
Arman (Selection) 5... 2525 ee oo 1355-2-2 3 10. 7 16. 7 6.00: 2 5esee— 
IBELOP IIT Are rn ses Sa eee eee ee 1543 5 8. 4 4, | BRD AE 1.0 
iBlaekhull * 25 Serer See ee bee ars pee 6251 3 24. 0 1947 lib. ee Bs 4.3 
(OPITMEAT 29 -c. Se ee eee 1436 4 9.5 Tiles 18h eee 
Wore A RVITRIS. ent eee 1559 3 7h 9.0 LITLE ES 
[eanredits aa) es feo RE pooh aK 5146 7 4.0 10. 0 G.' Oy). te ee 
IRIN ONG: ote te ee an ne ee 6700 3 Sow / BG 1 pike SATAN Cee Se 
Kparkofes Pep deves fo Pe iy cee fer 1442 8 De Dice adel: aes Selec eee ee 
WO e252 8 a ee ee 1583 10 9. 6 OF Oi esc cc ee 6 
WGlthe YP SRE ee 8 4207 6 14.0 LOL Rt ee 35 
Malakoff eett tag Sb ees hee 2208 4 11.5 15 tog eae = ol forty ene 2 
144 Ghia (if Der) ct faPoaegemcra lc pels, Site d Sai RT A do 6155 5 14. 0 0 I ee BS 2.0 
FP TGISS 5 (Bisons winery hie tow eee ied 1561 4 12.5 OD boa. Bk 3.0 
MPI OV pe. Sie a ee ee 1558 5 13. 0 hy od Hap bape oat 3. 4 
IDOL? FIG Us ei ie 1571 9 10. 4 D} 40s PSE 1.0 
10%) SE see. eee ee ae ROWE Gere ot Uns 2943 4 11.5 Oe belo hes 2.0 
1B fo leptin date Me MR, See up, abt 3055 4 12.5 O20*] be Se Akt 3.0 
Soft red winter: 
BiatomMuIN OG) Ae seso Snot a eee 3330 7 Tea Dol ilnccmme ones 1.0 
Miinhardic thi2osiy_ fi fae 380 5149 3 Livy Bf7 | ee ae 8.0 
Nebraska INO: 28... 20 ees a 147 3 10. 0 13. 0 Sil oo Sea een 
