BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 57 
responsible for the epidemic in 1938. It was isolated from 85 percent 
of all the collections of rusted grains and grasses obtained in the 
United States and was the most prevalent form for the fifth consecu- 
tive vear. Never before, since the physiologic-race survey was under- 
taken on an extensive scale, has any single race of rust been so 
predominant. While 4 ether races (38. £9, 1.. and 11) were rather 
widely distributed, varieties of grain resistant to race 56 in general 
escaped serious rust damage. 
BARBERRY BUSHES RUSTED HEAVILY IN 1938 
Before rust appeared on grains in southern Oklahoma barberry 
bushes in the Northern States were becoming i Lfected. Both the 
pycnial and aecial stages of the fungus wer< red on barberries 
iii Missouri by May 5, in Illinois by April 20, in Iowa and Nebraska 
by April 29, in South Dakota by May 27, in Minnesota by May 6, 
in North Dakota by June 6." Rust was spreading from barberry 
bushes to nearby grains and grasses in these States 4 to 6 weeks 
before ilfection became general on grain away from known bushes. 
Further evidence was obtained in 1938 to indicate that new hybrid 
races of the stem-rust fungus may be produced at the time infection 
occurs on the leaves of the' barberry. These hybrid races may prove 
capable of attacking new and improved varieties of grain that have 
been tested and found resistant to both parent races of the fungus. 
In 1938, as in previous years, many instances were encountered in 
which local epidemics of stem rust could be traced directly to the 
barberry bushes that were responsible for the initial inoculum. 
FIELD DEMONSTRATIONS CONDUCTED FOR EDUCATIONAL PURPOSES 
Educational work in connection with the barberry-eradication pr< 
gram in recent years has been conducted largely to stimulate the 
interest of property owners in keeping their lands free of barberry 
bushes once the initial eradication work has been completed. Fre- 
quently it has been possible, in cooperation with county extension 
agents and representatives of State departments of agriculture, to 
arrange field demonstrations where farmers and local businessmen 
could observe the damage caused by a few barberry bushes so situated 
as to spread rust directly to grain crops. Such demonstrations held 
in Iowa. Minnesota, Wisconsin, and Pennsylvania have created much 
interest in the objective- of the regional program. Each demon- 
stration has been held just at the time that fan-shaped spreadings of 
rust could be traced directly to the bushes serving as the source of 
inoculum. Similar demonstrations of actual eradication of barberry 
bushes, to show farmers how much chemical is required to kill bushes 
and the proper methods of applying it. were held in several States. 
Again this year information concerning the developmenl and 
spread of stem rust was submitted to the Department Pit-— Sei 
weekly during the growing season. More detailed reports were 
made available at frequent intervals to various units of the Depart- 
ment interested in current crop condition-. 
