UNITED STATES DEPARTMENT OF AGRICULTURE 
-^^"T"^^ 
In Cooperation with the 
North Dakota Agricultural Experiment Station 
DEPARTMENT BULLETIN No. 1120 
Washington, D. C. 
PROFESSIONAL PAPER 
October 26, 1922 
INVESTIGATIONS OF HEAT CANKER OF FLAX.^ 
By C. S. Reddy and W. E. Brentzel. Assistant Pathologists, Office %/" Cereal Inves- 
tigations. Bureau of Plant Industrie n^ ^"'•^^V 
Introduction 
Anthracnose canker 
Heat canker of flax, a nonparasitic type. 
Cause of heat canker 
Similar injury to other plants 
CONTENTS. 
Page. I Page. 
1 I Heat canker of flax, a nonparasitic type — 
2 i Continued. 
3 Preventive measures 15 
3 Summary 16 
14 Literature cited .A: 17 
INTRODUCTION. 
The seed-flax area of the United States coincides closely with the 
spring-wheat region of the Northwest, composed for the most part of 
the States of Minnesota, the Dakotas, and Montana. Within this 
area flax wilt, drought, and weeds are the most important limiting 
factors in flax production. Flax wilt has gradually pushed the center 
of flax production westward into uninfested areas, while the newly 
broken prairie sod with its absence of weeds has led it in the same 
direction. When the production of flax reached this semiarid section, 
complaints came from the growers that the plants often broke over 
at or near the surface of the soil, as though whipped off by the winds 
or gnawed by insects. 
Fortunately for flax production. Prof. H. L. Bolley early became 
its advocate in North Dakota and devoted the greater part of his 
time to it for a number of years. He found the cause of flax wilt and 
developed control measures in the form of seed selection, seed treat- 
ment, and the development of resistant varieties (L 2, 3, and 4)-^ 
This has helped to eliminate losses from diseases caused by parasitic 
seed-borne organisms. Further work {4 and 5) explained the cause 
of one type of flax canker. As this disease was very destructive in 
1 The investigations here reported have been conducted in cooperation with the department of plant 
pathology of the North Dakota Agricultural Experiment Station. The writers wish toacknowledge their 
indebtedness to Prof. H. L. Bolley for many helpful suggestions in the progress of the work and to Dr . 
A. G. Johnson for assistance in the preparation of the manuscript. 
* The serial numbers (itaUc) in parentheses refer to " Literature cited " at the end of this bulletin . 
5419— 22— Bull. 1120 1 
I 
