THE EFFECT OF FERTILIZERS ON THE DEVELOPMENT 
OF STEM RUST OF WHEAT 1 
By E. C. Stakman, Plant Pathologist, Division of Plant Pathology and Botany, Depart¬ 
ment of Agriculture, University of Minnesota, and Pathologist, Office of Cereal Investi¬ 
gations, Bureau of Plant Industry, United States Department of Agriculture, and O. S. 
Aamodt, Pathologist, Office of Cereal Investigations, Bureau of Plant Industry, United 
States Department of Agriculture 2 
INTRODUCTION 
For many years there has been an opinion that the severity of rust 
attacks on wheat and other cereals was influenced profoundly by available 
soil nutrients. Especially was it thought that heavy fertilization with 
nitrogenous manures was conducive to abundant development of rusts. 
Most farmers, and many scientists, did not distinguish between the dif¬ 
ferent kinds of rusts, so that many of the early observations have but 
little value. About ten or twelve years ago, however, many farmers in 
Minnesota and neighboring States asserted that the kind of soil on which 
wheat was grown, as well as the amount of barnyard manure applied, 
affected very greatly the development of stem rust, Puccinia graminis 
Pers. In some localities there also was a general impression that wheat 
grown on clover soil was very likely to be injured badly by the rust. These 
observations seemed to indicate that nitrogenous fertilizers predisposed 
wheat to attack by Puccinia graminis , and the results of controlled experi¬ 
ments made by several European investigators apparently supported 
these views. 
Comes (7) 3 , Spinks (30), Hiltner (12), Stranak (33) and others pub¬ 
lished the results of experiments which indicated that soil fertilization 
influenced profoundly the severity of stripe rust, Puccinia glumarum 
(Schm.) Erikss. and Henn., on wheat. Experiments conducted by the 
senior author (31) show that in general the absence or presence, in exces¬ 
sive amounts, of various nutrient substances, such as nitrogen and phos¬ 
phorus salts, did not directly affect the immunity or susceptibility of 
wheats to P. graminis . Conditions favoring normal host development 
increased the vigor of the rust. It seemed desirable to make more 
extensive experiments in the field, on different types of soil, and over a 
period of several years. Empirical experiments of a practical nature 
therefore were begun in 1914 and were continued for eight years. The 
writers tried to ascertain facts, the explanation of which was sought in 
special investigations. 4 
1 Accepted for publication Nov. 19,1923. Cooperative investigations between the Office of Cereal Investi¬ 
gations, Bureau of Plant Industry, United States Department of Agriculture, and the Department of Agri¬ 
culture of the University of Minnesota. Published with the approval of the Director, as Paper No. 293 of 
the Journal Series of the Minnesota Agricultural Experiment Station. 
2 The writers are greatly indebted to Dr. F. J. Alway, Chief of the Division of Soils, Department of Agri¬ 
culture, University of Minnesota, for advice and assistance and for placing the Crookston plats at their 
disposal; and to Dr. C. H. Bailey, head of the Section of Cereal Technology, Division of Biochemistry, 
University of Minnesota, for making certain analyses. They also are indebted to John H. Parker, F. J. 
Piemeisel, A. G. Newhall, and G. R. Hoemer, formerly of the Office of Cereal Investigations, and to C. R. 
Hursh, Agent, Office of Cereal Investigations, and Assistant Pathologist, Department of Agriculture, Univer¬ 
sity of Minnesota, for assistance in taking notes. 
* Reference is made by number (italic) to “Literature Cited," p. 377. 
4 Dr. Freeman Weiss and Dr. C. R. Hursh made these studies as a part of the cooperative project between 
the Office of Cereal Investigations, Bureau of Plant Industry, United States Department of Agriculture, 
and the Department of Agriculture of the University of Minnesota. The results will be published in sepa¬ 
rate papers. 
(341) 
Journal of Agricultural Research, 
Washington, D. C. 
Vol. XXVII, No. 6 
Feb. 9, 1924 
Key No. G-3S4 
