CEREAL RUST BULLETIN
Report No. 2
April 8, 1997
Issued by:
Cereal Rust Laboratory, Agricultural Research Service,
U.S. Dept. of Agriculture
University of Minnesota, St. Paul, MN 55108
(612) 625-6299 FAX (612) 649-5054
Internet: markh@puccini.crl.umn.edu
CRL web page: http://www.umn.edu/rustlab/
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€Sixty percent wheat leaf rust and oat crown rust severities were observed in
fields and plots in southern and central Texas by the first week in April.
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The winter-sown small grain crop is generally in good condition throughout the
United States. Wheat in southern and central Texas is two weeks behind
normal. Rain the first week in April throughout Texas, made conditions ideal
for plant growth. In Oklahoma and Kansas, wheat development is ahead of
normal and the majority of the crop is in good shape. In the southeastern
soft red winter wheat area, the crop is in good shape and ahead of normal
maturity.
Wheat stem rust
No stem rust was found in commercial fields or nurseries in southern and
central Texas by the first week in April.
Wheat leaf rust
During the first week in April, 60% wheat leaf rust serverities were observed
on lower leaves of susceptible cultivars in fields and nursery plots
throughout southern and central Texas (Fig. 1). For example, in nursery
plots, rust severities ranged from 60% on TAM 107 to 20% on Jagger to 0% on
TAM 300. In late March, leaf rust was unusually heavy in Oklahoma where it
survived the winter. In the southern tier of counties in Kansas, where leaf
rust overwintered, rust pustules were found on the top two leaves in early
April. Farther north in Kansas, rust was found on the lowest leaves. In
conclusion, leaf rust is increasing in the southern U.S. If there is no
freeze damage, leaf rust will be a problem in this area and also provide
inoculum for the wheat-growing areas farther north.
During early April, leaf rust was severe in plots of susceptible southern
soft red winter wheat cultivars in southern Louisiana, and many of the
cultivars that previously were resistant are showing significant rust
development this year. By early April, leaf rust was severe on susceptible
cultivars in southern Georgia and Florida.
From rust collections made in mid-December in southwestern Arkansas, the
following races were identified: MBBL, MBRL, and MFBL; and from rust
collections made in early January in southern Georgia and Alabama, the MBRL,
TFBL, TBBL, and TLGG races were identified. All of these races were
identified from rust collections made during the 1996 race survey. So far
this year, the number one identified race is MBRL which was the number one
race found in the 1996 race survey.
Wheat stripe rust
During the third week in March, wheat stripe rust was observed in California
on a new variety, UC 1041, in the Yolo county plots and in the Davis campus
nursery. In early April, foci of wheat stripe rust were found in fields of
the Express cultivar in the Sacramento Valley.
Oat stem rust
During the first week in April, hot spots of oat stem rust 0.5 m in diameter
were found in southern Texas fields and nursery plots. Along the roadside in
central Texas, traces of stem rust were observed on wild oat (Avena fatua).
The rains during the first week in April were good for rust infection and the
rust should increase to significant amounts in the next few weeks. This oat
stem rust development may provide inoculum for areas farther north, but the
lack of oat acreage in the central Great Plains tends to interrupt potential
epidemics.
This year, by late March, stem rust was increasing in oat varietal plots
in southern Louisiana where it generally can be found every year by early
March.
Oat crown rust
During the first week in April, crown rust was severe in southern and central
Texas fields and plots. Sixty percent severities were common on the most
susceptible cultivars in nursery plots and in some cultivars the rust was
killing the host. In some fields in southern Texas, overwintering hot spots 3
m in diameter with 40-60% severities were observed.
In late March, severe crown rust was found in varietal plots in southern
Louisiana.
Barley stem rust
As of April 2, no stem rust has been reported on barley in the U.S. this year.
Limited amounts of barley are grown commercially in the southern states. Stem
rust on barley rarely occurs in this area.
Barley leaf rust
During the first week in April, 10% leaf rust severities were observed on
lower leaves in a few barley plots in southern and central Texas. In the
other barley plots in the same nursery, lighter amounts were found.
Stripe rust on barley
In early March, barley stripe rust was found in winter barley plots at
Corvallis, Oregon. By late March, stripe rust pustules were found at low
levels in susceptible varieties within a 16 m diameter circle of the original
infected plots. By the first week of April, barley stripe rust was severe in
plots and strip tests on the Davis campus and Yolo county plots in California.
During the last week in March, no barley stripe rust was found in southern
Texas plots.
Rye rusts
During the first week in April, 40% leaf rust severities were observed on the
flag leaf in winter rye plots in central Texas. No rye stem rust has been
reported this year.
SPECIAL NOTE: Cereal Rust Survey Listserver and Enclosed/Attached Graphic
Files
Cereal Rust Survey Listserver
A cereal rust survey listserver (cereal-rust-survey@coafes.umn.edu) has
been created for the rapid exchange of information relating to the current
cereal rust situation in the U.S. By addressing a message to the single
list address, you can send your information to all subscribers in the
list. We would encourage anyone who might have information to share or
would like the latest information on the cereal rust situation in the U.S.
to subscribe to the listserver.
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Attached/Enclosed Graphic Files
Most email subscribers to the Cereal Rust Bulletin receive the maps, if
any, as enclosures or attachments to the email message containing the
Cereal Rust Bulletin. If you find this creates any problems or bogs down
your email, we would encourage you to pick up the maps from our home page
(http://www.umn.edu/rustlab/). If you would like to change to this
arrangement, please send an email to markh@puccini.crl.umn.edu requesting
that you no longer receive the graphic file with your emailed Cereal Rust
Bulletin.