BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 
63 
Dry salt and salt brine continue to be the most practical and 
effective chemicals available for eradication purposes. Chlorates 
were used to some extent in Colorado for cleaning up small areas and 
scattered bushes of Berberis fendleri. Bushes were dug only when 
it appeared that chemicals might injure nearby trees, shrubs, or 
other vegetation of value. 
During the year State W. P. A. projects were operated under the 
technical supervision of Bureau personnel in Colorado, Illinois, Min- 
nesota, Pennsylvania, and Virginia to supplement work made pos- 
sible with funds allotted to Federal agencies from emergency relief 
sources. 
STATUS OF BARBERRY ERADICATION 
i'lie status of the barberry-eradication program varies consid- 
erably in different States within the control area, and in different 
areas within individual States. In Montana, North Dakota, South 
Dakota, Wyoming, western Nebraska, and eastern Colorado the 
initial survey has been completed, and the work remaining to be done 
is of a clean-up nature which will involve one or more reinspections 
of known infested properties, educational work to eidist the aid of 
property owners in reporting or destroying bushes that may so far 
have escaped detection, and rust surveys to determine localities 
where local epidemics of the disease indicate possible sources of 
inoculum. 
In western Colorado, eastern Nebraska, Iowa, Missouri. Minnesota. 
Wisconsin, Illinois, Indiana. Ohio, and Michigan, where infested 
areas exist in greater numbers and are far more extensive, many of 
them involving all uncultivated lands in entire townships or even 
counties, the status of the program is not so far advanced. The 
initial eradication has been completed in most of the larger infesta- 
tions, but in many instances seedlings are known to be developing 
and must be destroyed before they in turn reach the fruiting stage. 
In these States, as in those farther west, detailed records including 
maps have been made of all locations where barberry bushes were 
found, thus simplifying future clean-up work. 
There has been no change in the policy of restricting field opera- 
tions in Pennsylvania, Virginia, and West Virginia to the more 
important grain-growing valleys. These States are not subject to 
the sweeping winds that frequently distribute rust spores for great 
distances in the Plains area, and wherever bushes are destroyed there 
is a marked reduction the following year in the amount of rust in 
the vicinity. 
STEM RUST DAMAGE NEGLIGIBLE IN 1939 
The development and spread of stem rust was studied in 1939 
along the following three major lines: (1) Field observations were 
made throughout the United States and in Mexico to determine 
where, and under what conditions, stem rust caused appreciable 
damage: (2) nearly 2,000 prepared slides (spore traps) were exposed 
during the period April 1 to June 30 at 23 selected stations in 20 
States, and an examination of these slides indicated on what date-, 
and to what extent, rust spores were widely distributed by air cur- 
rents; and (3) specimens of rusted grain were collected from rep- 
