UNITED STATES DEPARTMENT OF AGRICULTURE 
In cooperation with the Idaho, Iowa, Kansas, Missouri, and Washington 
Agricultural Experiment Stations and the Brooklyn Botanic Garden 
DEPARTMENT BULLETIN No. 1275 
.JnfnfSB!^. 
Washington, D. C. 
April, 1925 
VARIETAL SUSCEPTIBILITY OF OATS TO LOOSE AND COVERED SMUTS 1 
By George M. Reed, Curator of Plant Pathology, Brooklyn Botanic Garden, 
formerly Pathologist in Charge of Cereal-Smut Investigations, and Marion A. 
Griffiths and Fred N. Briggs, Assistant Pathologists, Office of Cereal Inves- 
tigations, Bureau of Plant Industry 
CONTENTS 
Page 
Introduction •_ 1 
Review of literature 1 
Characteristics of the oat smuts 5 
Field experiments 6 
Experimental procedure and results 6 
Page 
Field experiments— Continued. 
Discussion of results 29 
Greenhouse experiments 34 
Summary 36 
Literature cited 38 
INTRODUCTION 
In recent years numerous investigations have been undertaken to 
determine the resistance of varieties of economic plants to various 
diseases. The importance of disease-resistant varieties in the 
prevention of losses caused by parasitic organisms has long been 
emphasized, and their discovery and utilization is a well-recognized 
method of plant-disease control. 
The investigations, 2 the results of which are presented in this 
bulletin, are a continuation and expansion of those previously con- 
ducted by the senior writer at the Missouri Agricultural Experiment 
Station. 
REVIEW OF LITERATURE 
Previous to a recent publication by the senior writer (IS) 3 very 
little study had been made of the resistance of oat varieties to loose 
smut, Ustilago avenae (Pers.) Jens., and covered smut, U. levis 
(K. and S.) Magn. Slight variations in the percentage of smut 
infection in different varieties of oats were noted by Arthur (2), in 
New York. The infection varied considerably, and none of the 
varieties was entirely free. Plumb {12) recorded from 1 to 3 per 
1 Issued also as Brooklyn Botanic Garden Contributions No. 34. 
2 The writers desire to acknowledge the valuable assistance in conducting these experiments which they 
have received from Supt. L. C. Aicher, formerly of the Aberdeen, Idaho, substation; Dr. I. E. Melhus, of 
the Iowa station; Prof. J. H. Parker and Prof. L. E. Melchers, of the Kansas station; Dr. W. E. 
Maneval, of the Missouri station; and Dr. E. F. Gaines, of the Washington station, as well as from others 
mentioned later in the text. Miss Naomi Howells rendered valuable assistance in connection with the 
experiments at the Brooklyn Botanic Garden. 
3 Serial numbers (italic) in parentheses refer to "Literature cited," at the end of this bulletin- 
96995°— 25t 1 
