UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1383 
Washington, D. C. 
March, 1926 
SINGLE-BATH HOT-WATER AND STEAM TREATMENTS OF SEED WHEAT 
FOR THE CONTROL OF LOOSE SMUT 
By V. F. Tapke, 1 Associate Pathologist, Office of Cereal Investigations, Bureau of 
Plant Industry 
CONTENTS 
Page 
Introduction 1 
Single-bath hot-water treatments.. 2 
Previous investigations 2 
Methods and materials 3 
Effects of single-bath hot-water treat- 
ments in 1920-21... 4 
Effects of single-bath hot-water treat- 
ments in 1921-22 6 
Effects of single-bath hot-water treat- 
ments in 1923-24.. 13 
Methods of applying single-bath treat- 
ments 16 
Page 
Steam treatments. - 19 
Previous investigations 20 
Methods and materials 20 
Effects of steam treatments on germina- 
tion, emergence of seedlings, smut con- 
trol, and yield 22 
Discussion - 25 
Summary and conclusions 25 
Literature cited. 28 
INTRODUCTION 
Loose smut, caused by the fungus Ustilago tritici (Pers.) Jens., 
is one of the commonly known destructive diseases of wheat. Rec- 
ommendations for its control in this country have been confined 
almost entirely to treatment of the seed by the modified hot-water 
method. In general, this treatment is carried out as follows: A 
small quantity of seed wheat in a porous container is (1) presoaked 
for four to six hours in unheated water. (2) dipped momentarily in 
water heated to about v 49°fC, (3) immersed for 10 minutes in water 
maintained at 54° C, and (4) either dipped in cold water or spread 
out in a thin layer without dipping. 
There is no doubt that the modified treatment completely controls 
loose smut C£, 5, 13, 15) , 2 but reports from numerous sources show that 
it is practiced only to a limited extent, largelv because the modified 
treatment is (1) relatively complicated and teclious for the individual 
farmer to apply, (2) it soaks "the seed and this often leads to post- 
1 The writer makes grateful acknowledgment to W. H. Tisdale, C. R. Ball, and H. B. Humphrey for 
helpful criticisms of the manuscript, to X. C. Ellis for the drier used in the experiment? with steam treat- 
ments, and to the agronomists in the wheat projects of the Office of Cereal Investigation? and R. O. East, 
D. D. Ball, and M. E. Cromer, county agricultural agents in Indiana, for supplying the seed samples used 
in the experiments. 
'Serial numbers (italic) in parentheses refer to "Literature cited," at the end of this bulletin. 
67896— 26t 1 
