CEREAL RUST BULLETIN
Report No. 6
June 4, 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
markh@puccini.crl.umn.edu
http://www.crl.umn.edu/
rust survey mail list: cereal-rust-survey@coafes.umn.edu
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€Leaf rust is heavy on wheat in Oklahoma and southern Kansas,
where significant yield losses are predicted.
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The small grain harvest is underway from northern Georgia to north
central Texas. Winter wheat condition is rated slightly better
than last week as a result of moisture and enhanced grain filling
in the central Great Plains. Last week, in most of the northern
small grain growing area, dry weather allowed for excellent
planting progress and seeding was ahead of last year and near the
5-year average.
Wheat stem rust
In late May, the only new reports of wheat stem rust were traces
in
northwestern Arkansas and central Texas varietal plots. In
central Texas, the crop was near maturity and hot dry weather in
Arkansas hastened maturity. If the stem rust from Arkansas moves
north and east it could still cause problems in Indiana where cold
spring weather delayed crop development two weeks behind normal.
Wheat leaf rust
During the third week of May, in north central Oklahoma, 60% wheat
leaf rust severities were observed on the flag leaves of many of
the cultivars growing in fields and plots. In north central
Oklahoma varietal plots, cultivars like Karl 92, 2163 and Chisholm
had 60% severity readings, while rust severities in cultivars like
Custer, Jagger and 2137 were less than 5%. Rust losses to leaf
rust in Oklahoma this year could be near 10%. In mid-May, 20%
leaf rust severity readings were observed on Triticum cylindricum
(goatgrass) in western Oklahoma. This was the heaviest leaf rust
observed on goatgrass in the last five years.
In late May, in south central Kansas fields, 80% leaf rust
severities were common on the flag leaves of susceptible winter
wheat cultivars where rust overwintered. In varietal plots in
south central Kansas, leaf rust had decimated most of the
cultivars and the only cultivar showing some resistance was Big
Dawg. Throughout northern Kansas, leaf rust development has been
slow. The cooler than normal night temperatures during the last
part of May may have been one of the reasons why rust did not
develop as fast as expected. Leaf rust losses in Kansas are still
expected to be in the 2-5% range.
In late May, wheat leaf rust was severe in varietal plots and
light
in fields in the bootheel of Missouri, northeastern Arkansas and
western Tennessee. In varietal plots in eastern Virginia,
severities ranged from 10 to 50%.
During late May, traces of leaf rust were reported in central
Michigan plots and east central fields.
Trace amounts of leaf rust were found in south central and
southeastern North Dakota on June 2. This is the first report of
leaf rust in North Dakota.
In late May, wheat leaf rust was light in the Skagit Valley of
western Washington, but because of the recent rains rust is
expected to increase.
The preliminary leaf rust race identifications for 1997 are shown
in Table 1. The race identifications for Texas are from the
southern part of the state where this year many new races for the
area were found. Races MBNL, MBTL and MCDL were not previously
identified in Texas. The main difference in these races is the
Lr17 virulence. Lr17 is part of the leaf rust resistance in
Jagger.
TABLE 2. Wheat leaf rust races identified through June 2, 1997
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Number of isolates by state
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Prt code Virulence formula* AL AR GA LA OK TX
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MBBL 1,3,10 1
MBNL 1,3,3ka,10,17 4
MBRL 1,3,3ka,10,11,30 3 6 2 6
MBTL 1,3,3ka,10,11,17,30 1
MCBL 1,3,10,26 2
MCDL 1,3,10,17,26 9
MCRL 1,3,3ka,10,11,26,30 2
MDBL 1,3,10,24 6
MDGL 1,3,10,11,24 1
MDRL 1,3,3ka,10,11,24,30 5
MFBL 1,3,10,24,26 3
MFDL 1,3,10,17,24,26 1
MFRL 1,3,3ka,10,11,24,26,30 1
MFTL 1,3,3ka,10,11,17,24,26,30 1
TBBL 1,2a,2c,3,10 1 2
TDBL 1,2a,2c,3,10,24 2 10
TDRL 1,2a,2c,3,3ka,10,11,24,30 2
TFCL 1,2a,2c,3,10,24,26,30 1
TFGL 1,2a,2c,3,10,11,24,26 2
TLGG 1,2a,2c,3,9,11,18 2
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Number of isolates 3 12 4 2 2 53
Number of collections 2 6 2 1 1 30
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* Single gene resistances evaluated:
Lr1,2a,2c,3,3ka,9,10,11,16,17,18,24,26,30
Wheat stripe rust
In late May, traces of stripe rust were found in wheat fields in
the
bootheel of Missouri and western Tennessee. The hot temperatures
this week probably will disrupt the development of stripe rust in
this area.
In late May, 90% stripe rust severities were observed on
susceptible
wheat cultivars (boot to heading growth stages) in the Skagit
Valley of western Washington. East of the Cascades in Washington,
wheat stripe rust has not increased much the last 3 to 4 weeks
primarily because of dry weather.
Oat stem rust
There have been no new reports of oat stem rust since the last
bulletin.
Oat crown rust
Throughout the southern U.S., crown rust has continued to increase
on oats that are not mature. Inoculum from the south is likely to
have an impact on crown rust increase farther north.
In late May, aeciospores, which can infect oat, were found on
buckthorn leaves in southern Minnesota and southern Wisconsin.
Buckthorn bushes are the alternate host for crown rust and
generally provide the initial spores for crown rust infections of
the northern oat crop.
Barley stem rust
Barley stem rust was first reported, this year, on May 19 in
barley
plots in south Texas at Beeville. Limited amounts of barley are
grown commercially in the southern states. Stem rust on barley
rarely occurs in this area.
Barley leaf rust
In late May, light amounts of barley leaf rust were reported in
south central Pennsylvania and in the Skagit Valley of western
Washington.
Stripe rust on barley
In late May, barley stripe rust was increasing in spring barley
plots at Corvallis, Oregon. Stripe rust was severe (90%) on
susceptible winter cultivars in the boot to heading growth stages
in the Skagit Valley of western Washington. As of late May, there
have been no reports of barley stripe rust being found east of the
Cascade Mountains in the Pacific Northwest.
Rye rusts
There have been no new rye rust reports since the last bulletin.
Stem rust on barberry
During mid-May, aecial development was observed on barberry bushes
(alternate host for stem rust) in south central Wisconsin.