BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 
55 
BU. 
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Average Annual Bushel and Dollar Losses by 6-Year Periods 
1918-23 
1924-29 
1930-35 
Figure 1. — Reduction in losses of wheat, oats, barley, and rye due to 
stem rust as control work has progressed. 
Regulation of barberry planting stock strengthened 
Both foreign and domestic regulations controlling the movement 
of barberry plants have been strengthened to prevent the distribution 
of off-type susceptible stock. In recent years increasing numbers 
of susceptible Berberis thy/ribergii hybrids were located in nurseries 
and landscape plantings. Nurserymen were suffering losses from im- 
pure stock, and four-fifths of the area in the eradication States that 
had been cleared of rust-spreading barberries was in danger of becom- 
ing reinfested with such bushes. 
In one nursery a vigorous red-leafed plant was taken from a block 
of Japanese barberry, and a large number of plants of this so-called 
improved strain were propagated and sold without the knowledge 
that it was a susceptible hybrid. This plant was used as a source of 
cuttings, and in 1948 the nursery had 2,700 vegetatively propagated 
plants and 10,000 cuttings. Some of the bushes were infected with 
stem rust, and the disease had spread to wild grasses nearby. The 
nurseryman had assumed that the original plant was immune to stem 
rust because it had been selected from the resistant Japanese barberry 
stock. All the stock was condemned and destroyed, but some of it had 
been sold to nurseries and individuals in 19 States before 
its discovery. 
Nurserymen are encouraged to grow only rust-resistant barberries 
for the trade and to remove all susceptible plants within and around 
their nurseries to prevent hybridization. They are responding favora- 
bly and cooperatively in this work. 
During the year barberry bushes were removed from areas totaling 
25,390 square miles, of which 18,271 square miles was rework and 7.1 L9 
initial work. Nearly 13,000,000 barberry bushes were cTestroyed on 
5,523 new and 1,757 reinfested properties in 225 counties. 
