BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE .).) 
As a result of the inspection of 11,400 acres of nursery stock, 23,750 
rust-susceptible barberry bushes were destroyed. Forty nurseries 
were found to meet quarantine requirements, and interstate shipping 
permits were granted. Two failed to qualify, 2 required no permits. 
and no action was taken in regard to 3 nurseries where further clean- 
up work is necessary. 
.V year ago a review of nursery catalogs on file in the Department 
of Agriculture Library indicated that about 40 miseries (all outside 
the quarantined area ) were advertising susceptible species of barberry 
for sale. This number has now been reduced to about 30. and it is 
expected that within a very few years practically all nurseries will 
have discontinued the sale of other than immune species. 
Again this year all available species of barberry not definitely 
classified with respect to their reaction to the stem-rust fungus were 
inoculated under natural conditions. There are known to be more 
than 150 different species of barberry in the United States, most of 
which have been introduced from foreign countries. Of this number, 
only 32 are immune to attack by the stem-rust fungus. 
STEM RUST PREVALENT OVER LARGE AREA IN 1938 
Again in 1938 stem rust of small grains became epidemic over 
extensive areas from Texas to the Canadian border. However, owing 
to the predominance of the rust -resistant Thatcher wheat in Minne- 
sota and certain sections of North Dakota and hot. dry weather that 
checked the development of the fungus and matured crops prema- 
turely in South Dakota and certain parts of North Dakota, rusl 
losses in the spring wheat area this year were not nearly so great as 
in 1935 or 1937. 
A discussion of the factors contributing to the epidemic of 1938 
must include some mention of rust observations made in the fall of 
1937. Stem rust was prevalent on late oats, volunteer grains, and 
certain native grasses, particularly wild barley (Hordeum jubabwm,) 
in southern Minnesota, IoAva, and northern Missouri in August L937. 
There is evidence that from here rust spores were blown southward 
early in the fall, for infection was found on volunteer oats near 
Guthrie, Okla., on October 24. and at several points in Oklahoma and 
Kansas a month later. There is little doubt that fall-sown grains in 
Texas and northern Mexico became infected late in the season and 
that the rust survived the winter of 1938-39 in the uredial or spread- 
ing stage. 
To determine, if possible, the extent to which rust in Mexico con- 
tributed to the development of the disease later in the season in Texas 
and States farther north, a rust survey, conducted in cooperation with 
representative- of the Institute Biotecnico, Mexican Department of 
Agriculture, was made in February, and again in April, of the more 
important grain-growing areas in Mexico. 
Specimens of rusted grain were obtained from representative locali- 
ties within each geographical area and studies made To determine the 
particular races of the fungus that were present. Southern Mexico 
apparently did not contribute to the epidemic in the United State- in 
1938. nor could it have furnished all the inoculum for northern Mexico. 
Willi the exception of one collection of race 24, only race- 59 and 38 
were identified from specimens obtained in southern Mexico in 1938. 
