Feb. 9, 1924 
Effect of Fertilizers on Stem Rust of Wheat 
353 
plants which have been fertilized properly can sometimes yield well 
even when heavily infected with stem rust. 
There appeared to be a direct correlation, however, between the kind 
and amount of fertilizer applied and the percentage of infection by orange 
leaf rust, Puccinia triticina (Table IV). The percentages are not high 
because Haynes Bluestem is moderately resistant and Iumillo is very 
resistant in the field. The range in percentage of infection on Haynes 
Bluestem was from 10 to 40, the highest being in the nitrogen plats. The 
average percentage of infection in those plats which had received only 
nitrogen was 36; in those which had received nitrogen and phosphorus 
it was 29; in the phosphate plats, 22; in the potash plats, 17; in the 
phosphorus-plus-potassium plats, 21; while in the unfertilized control 
plat, it was 23. There was only a trace of leaf rust on Iumillo in all plats 
except the control and those which had received sodium nitrate. The 
highest percentage of infection was 10 in the plat receiving 1,000 
pounds of nitrogen. 
Evidently fertilization with sodium nitrate caused increased develop¬ 
ment of leaf rust, and phosphorus and potassium had some tendency to 
prevent its development, but it is quite likely that the effect may have 
been indirect. On the natural fertilizer plats there appeared to be no 
correlation between fertilization and development of leaf rust. 
Unfortunately, very little leaf rust developed in any of the years sub¬ 
sequent to 1915, so additional data were not obtained and definite con¬ 
clusions could not be drawn. 
Table IV .—The effect of commercial fertilizers on the degree of infection of Puccinia 
triticina in IQI$ on Haynes Bluestem and Iumillo wheats in the plats on University 
Farm , St. Paul , Minn. 
Infection. 
Fertilizer. 
Fertilizer, kind and amount (pounds) per 
acre. 
Kind. 
Amount 
per acre. 
Sodium nitrate. 
None. 
Potassium 
chlorid. 
1,000 
500 
250 
1,000 
500 
250 
Pounds. 
Percentage of leaf rust, Haynes 
Bluestem. 
/ 25 
27 
22 
15 
IO 
15 
15 
Percentage of leaf rust, Iumillo. 
0) 
2 , OOO 
l 5 
2 
1 
I 
I — 
I — 
I — 
Percentage of leaf rust, Haynes 
1 
1 
Bluestem. 
vC 
Ps 
/ 30 
30 
25 
25 
15 
20 
20 
Percentage of leaf rust, Iumillo. 
O 
I, OOO 
l 5 
3 
1 — 
I — 
1 
I — 
I — 
Percentage of leaf rust, Haynes 
rP 
Pi 
Bluestem. 
/ 40 
35 
3 ° 
25 
12 
15 
15 
Percentage of leaf rust, Iumillo. 
"0 
5 °° 
l 5 
3 
1 
I 
I — 
I — 
I — 
Percentage of leaf rust, Haynes 
< 
i 
l 
Bluestem. 
Mah a 
/ 40 
40 
27 : 
2 3 
20 
15 
15 
Percentage of leaf rust, Iumillo. 
, 
lio-f 
5 
7 ; 
! 3 
! 
I 
I — 
I — 
EXPERIMENTS WITH COMMERCIAL FERTILIZERS PLUS NATURAL FERTILIZERS 
IN 1915 
As previously outlined, the second method used in these experiments 
consisted in growing wheat on soil enriched with such natural fertilizers 
as barnyard manure, clover, and alfalfa, both alone and in various com- 
