UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 1029 
Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 
J&^^J-U 
Washington, D. C. 
PROFESSIONAL PAPER 
March 28, 1922 
SEED TREATMENT AND RAINFALL IN RELATION 
TO THE CONTROL OF CABBAGE BLACK-LEG. 
By J. C. Walker, Assistant Professor of Plant Pathology, University of 
Wisconsin, and Pathologist, Office of Cotton, Truck, and Forage Crop Disease 
Investigations. 1 
CONTENTS. 
Page. 
Introduction _ 1 
Effect of fungicidal treatment in the 
laboratory upon seed and the seed- 
borne fungus 3 
Heat and desiccation 5 
Formaldehyde solution 7 
Hot water 9 
Mercuric-chlorid solution 10 
Summary of laboratory seed- 
treatment experiments 12 
Field trials with treated seeds 13 
Development of the disease in 
the seed bed 13 
Page. 
Field trials with treated seeds — Con. 
Relation of rainfall to the de- 
velopment of the disease.- 14 
Importance of spread in the 
seed bed as compared with 
dissemination in the field 17 
Seed-bed trials at Madison, Wis., 
in 1919 18 
Results with treated seeds in 
commercial fields 20 
Importance of disease-free seeds 23 
Summary 25 
Literature cited 27 
INTRODUCTION. 
The black-leg of cabbage, first noted as occurring in America by 
Manns (7), 2 has become one of the most serious and widespread 
maladies of this crop. Henderson (3), who, on the basis of his ear- 
lier studies in Wisconsin, has given the most complete treatise on 
the disease, demonstrated that cabbage seeds which had been invaded 
by the causal fungus, Phoma ling dm (Tode) Desm., were a common 
1 The major portion of the work reported upon herewith was carried on at the labora- 
tory of plant pathology of the University of Wisconsin as a cooperative project between 
the university and the United States Department of Agriculture. Along with this, the 
writer has had opportunity for field studies in some of the chief cabbage-growing sections 
in the Eastern, Western, and Southern States. The writer wishes to express his appre- 
ciation to Prof. L. R. Jones for the helpful advice and criticisms received during the 
course of the investigation and to Dr. W. B. Tisdale and Miss Ruth Tillotson for assist- 
ance in part of the field observations and laboratory experiments. 
2 The serial numbers (italic) in parentheses refer to "Literature cited" at the end of 
this bulletin. 
73603°— 22— Bull. 1029 1 
