16 
amounts and distribution of the seasonal precipitation. The yields of 
the durum wheats were considerably reduced in 1910, on account of 
hot winds at flowering time which prevented fertilization. In 1911 
the wheat sown in the spring did not emerge until August. The 
failure in 1912 was caused by a deficient supply of soil moisture in 
the spring, together with the low precipitation during May and June. 
In 1916 the wheat was badly injured by rust. 
The durum varieties have outyielded the common varieties in 
nearly all seasons. This was due only in part to the greater resistance 
of durum wheat to rust and drought, for the durum varieties have 
given the highest yields in the most favorable seasons, The Kubanka 
variety, C. I. No. 1516, has the highest average yield during the en- 
COMMOW 
BLUESTEM: 
F/F?Y/V£S 
PRESTON.' 
J./90OG/9' 
/9R/V/9UTK/9 
Y/ELP FEZ? /?C/?E 
/O AS 20 
26 
30 
Wt/8.3 BU. 
\/6.3 9U 
/3.2BU 
/6.BBU 
BU, 
2/.SB/. 
M22A BU. 
Fig. 5. — Diagram showing the average yields, in bushels per acre, of seven varieties 
of spring wheat on dry land at the Belle Fourche Experiment Farm during the 7-year 
period from 1913 to 1919, inclusive. 
tire 12 years and also during the 7-year period, 1913 to 1919, inclu- 
sive. This variety appears to be slightly more productive than the 
Kubanka strain, C. I. No. 1140, and is slightly different in appearance. 
A head of Kubanka wheat is shown in figure 4. 
Several other durum wheat varieties yielded about as much as or 
even more than Kubanka during the three years 1917, 1918, and 1919. 
These small differences probably are not significant. 
Marquis is the highest yielding variety of common wheat. During 
the period from 1913 to 1919, inclusive, it outyielded all other com- 
mon-wheat varieties. A head of Marquis wheat is shown in figure 4. 
Manchuria, the second highest yielding common wheat, is a soft 
wheat of low milling and baking value. The Power, Haynes, and 
Preston varieties show average yields since 1913 considerably below 
that of Marquis. The yields of the leading varieties grown since 
1913 are shown graphically in figure 5, 
