GENETICS OF BUNT RESISTANCE IN WHEAT ‘ 
By E. F. Gaines 
Cerealist in Farm Crops, Washington Agricultural Experiment Station, and Agent, 
Office of Cereal Investigations, Bureau of Plant Industry, United States Department 
of Agriculture 
INTRODUCTION 
The losses due to bunt, Tilletia tritici (Bjerk.) Wint., in the Pacific 
Northwest have been steadily increasing for the past 25 years, not¬ 
withstanding the most earnest efforts on the part of scientists and farmers 
to reduce them. The seed has practically always been treated with 
blue vitriol or formaldehyde, but in spite of every precaution the winter 
wheat often contains from 10 to 50 per cent of bunted heads at har¬ 
vest time, apparently due to soil infection from wind-borne spores. 
In the State of Washington alone the most conservative estimates place 
the losses at more than 1,000,000 bushels of wheat annually. The 
bunt problem has caused, and is causing, more interest and anxiety 
than any other of like nature through the winter wheat districts. Spring- 
sown wheat seldom produces a bunted crop if the seed has been care¬ 
fully disinfected, the spores in the soil having perished during the winter. 
The work has been closely linked with the other cereal and patholo¬ 
gical investigations at the Washington Agricultural Experiment Station, 
and many friends and coworkers have contributed to the material in 
hand. Acknowledgment is here made to the various members of the 
staffs of the Washington Station and the Office of Cereal Investigations, 
Bureau of Plant Industry, United States Department of Agriculture, 
for their ever-ready help and enthusiasm; to E. M. East for helpful 
suggestions and criticism of the manuscript, and also to H. B. Humphrey, 
H. M. Woolman, E. G. Schafer, and F. D. Heald for suggestions and 
corrections in the presentation of the subject matter. 
When the writer became assistant cerealist of the Washington Agri¬ 
cultural Station in 1911, many inquiries were coming in from farmers 
concerning control measures for bunt in winter wheat. The limita¬ 
tions of seed treatment were well known, and soil sterilization seemed 
impracticable under the extensive system of wheat raising on the great 
farms of the winter-wheat belt. The possibility of obtaining or develop¬ 
ing a strain that would resist the attacks of the fungus and at the same 
time fulfill the requirements of winter hardiness, prolificacy, milling 
quality, etc., seemed the most promising solution of the problem. 
Accordingly hundreds of varieties from the principal wheat districts of 
the world have been introduced and many hybrids have been made in 
an attempt to find or develop such a wheat. Preliminary reports 
( 13 , 14) 2 of this work have already been published. 
The following paper deals with that part of the investigation con¬ 
cerning the comparative resistance of different wheats and the inheri¬ 
tance of the factors that cause resistance, as expressed in the hybrid 
segregates of succeeding generations. 
1 Accepted for publication August 31,1921. Submitted to the faculty of the Bussey Institution of Harvard 
University in partial fulfillment of the requirements for the degree of doctor of science, April 29, 1921. 
8 Reference is made by number (italic) to “Literature cited, ” p. 476-479- 
Journal of Agricultural Research, 
Washington, D. C. 
aby 
Vol. XXIII, No. 6 
Feb. 10, 1923 
Key No. Wash.-i 
25622—23-5 
(44s) 
