JOURN AL OF ACmammAL RESEARCH 
Voe. XXVI Washington, D. C., Nov. 3, 1923 No. 5 
INFLUENCE OF SOIL TEMPERATURE AND MOISTURE 
ON INFECTION OF WHEAT SEEDLINGS BY HELMIN- 
THOSPORIUM SATIVUM 1 
By H. H. McKinney 2 
Pathologist , Office of Cereal Investigations , Bureau of Plant Industry , United States 
Department of Agriculture 
INTRODUCTION 
While it is not the purpose of this paper to deal with all phases of the 
Helminthosporium disease of wheat, it seems advisable at this time to 
summarize the general situation concerning the disease. The chief 
purpose of this paper is to present the results of field observations and 
preliminary experiments bearing on the influence of soil temperature 
and soil moisture on certain phases of seedling infection in spring and 
winter wheat and, to a limited extent, in spring barley. 
When the writer began the investigation of the take-all and the rosette 
diseases of wheat it became evident that these diseases were in many 
cases intimately associated with the Helminthosporium disease and also 
with other wheat diseases which were likewise obscure. This necessitated 
a study of certain phases of the Helminthosporium disease in order that 
the other maladies might be properly interpreted. 
Although the Helminthosporium disease of wheat had attracted little 
attention among plant pathologists prior to the discovery of the rosette 
disease of wheat in Madison County, Ill., in 1919 (ji), 8 it was known to 
occur in several of the spring-wheat States and, to a limited extent, in 
the winter-wheat area. While little had been published in connection 
with the Helminthosporium disease, cereal pathologists in the spring- 
wheat belt and adjacent areas were fairly familiar with its general symp¬ 
toms and characteristics. 
Beckwith (1) and Bolley ( 2 ) were the first to show that wheat plants 
may be attacked by a Helminthosporium and that this organism is 
associated with poor wheat yields in the spring-wheat area. E. C. 
Johnson ( 6 ) was the first to demonstrate the pathogenicity of Helmin¬ 
thosporium on wheat seedlings. While he called the species with which 
he worked Helminthosporium gramineum Rabh., it is evident from the 
behavior of his fungus in inoculation experiments that, in reality, he was 
working with H. sativum P. K. and B. 
1 Accepted for publication May 2, 1923. The greenhouse and laboratory studies reported in this paper 
were carried on cooperatively between the Office of Cereal Investigations, U. S. Department of Agriculture, 
and the Wisconsin Agricultural Experiment Station, Madison, Wis. The field studies were conducted 
near Granite City, Ill., in cooperation with the Illinois Agricultural Experiment Station in connection 
with the investigations of the rosette disease of wheat. 
2 The writer wishes to express his appreciation to Prof. L. R. Jones and Dr. A. G. Johnson for the many 
suggestions concerning the work herein reported, and to Mr. R. W. Leukel for assistance in conducting 
the greenhouse experiments. 
3 Reference is made by number (italic) to “ Literature cited,” p. 217. 
Journal of Agricultural Research, 
Washington, D. C. 
agb 
(19s) 
Vol. XXVI, No. 5 
Nov. 3. 1923 
Key No. G-333 
60376—23-1 
