STEM RUST AND THE BARBERRY 
( Puccinia graminis Pers.) 
LIFE HISTORY 
The stem rust disease of wheat, oats, barley, and rye is one of the 
tive of all the fungus diseases that attack small grains. Every year 
yield and quality of these crops in some areas. In epidemic years 
iosses in the United States of more than 180,000,000 bushels of grain. 
In some areas, the fungus lives part of its life on grains and grasses and part on 
certain barberries. During the life cycle it produces several distinct kinds of tiny, 
seedlike spores. Spores scattered by the wind transmit the fungus from one host 
plant to another. There are several varieties and numerous races of the stem 
rust fungus, which differ in their ability to attack the different kinds and varieties 
of grain. 
In the northern half of the United States stem rust overwinters on wild grasses 
and grain straw in the black, or teliospore, stage. The overwintered teliospores 
germinate in the spring, producing sporidia, or secondary spores, which infect the 
leaves of rust-susceptible barberries. These spores cannot infect grains and 
grasses. When the fungus becomes established on the barberry, the pycniospore, 
or sexual stage, appears on the upper surface of the leaf. In this stage, hybridiza- 
tion may take place between different races. Occasionally new races of the fungus 
are thus produced, which can attack varieties of grain previously considered 
resistant. The aeciospore, or cluster-cup, stage is produced on the under side of 
the infected barberry leaves. These spores infect nearby grains and grasses, on 
which the red urediospore, or repeating stage, of the fungus develops. Under 
favorable weather conditions several generations of red spores may develop on 
grains or grasses during a single season. Myriads of these spores are carried by 
the wind from plant to plant and from grainfield to grainfield throughout the 
growing season. As the infected grains and grasses mature, the black, or over- 
wintering, spores develop, and the life cycle is completed. 
In the South, the rust may overwinter on grains or grasses in the red, or repeating 
stage and spread north as the season advances. Rust from this source spreads to 
grainfields in the North somewhat later than that from the barberry, and under 
weather conditions favorable for rust development may cause widespread damage. 
CONTROL 
The United States Department of Agriculture is cooperating with State agencies 
in the eradication of rust-susceptible barberries to control the stem rust disease 
of small grains. The removal of these bushes eliminates early-spring sources of 
stem rust inoculum and destroys the plants on which races of the fungus breed. 
There are many species and varieties of barberries. Most of them are susceptible 
to stem rust, but a few are immune or highly resistant. This disease is controlled 
by the following methods: 
1. Use chemicals to destroy rust-susceptible barberries. 
(a) Apply common crushed rock salt around the crown of each barberry. 
About 10 pounds is needed to kill a 5-foot bush. 
(b) Where the use of salt may endanger livestock or poultry, treat the 
crown of a 5-foot barberry with about 1 gallon of kerosene to kill the 
bush. 
(c) Ammonium sulfamate or 2,4-dichlorophynoxyacetic acid (2,4-D) may 
be used to kill barberries. The canes are cut off at the crown and the 
freshly-cut surfaces treated with small amounts of chemical in con- 
centrated form. Only experienced persons should use this method. 
2. Use approved rust-resistant varieties of grain. 
Plant breeders have produced varieties of small grains highly resistant 
to the common races of stem rust. Follow the recommendations of your 
State experiment station in the selection and planting of these varieties. 
3. Use approved cultural practices. 
On areas where stem rust is a serious problem, sow spring grain crops 
early and use early maturing varieties. Grain that matures early may 
escape serious damage from stem rust. Winter crops should be sown 
according to recommended seeding dates. 
October 1948 
U. S GOVERNMENT PRINTING OFFICE: 1948 
MI)S. COMP. ZOOL. 
LIBRARY 
JAN 17 1949 
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For sale by the Superintendent of Documents, U. S. Government Printing Office 
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804663—48 
