CEREAL RUST BULLETIN
Report No. 6
June 16, 1998
Issued by:
Cereal Disease Laboratory
U.S. Department of Agriculture
Agricultural Research Service
University of Minnesota
1551 Lindig St, St. Paul , MN 55108-6086
(612) 625-6299 FAX (612) 649-5054
markh@puccini.crl.umn.edu
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_____________________________________________________________________________
* Wheat stripe rust was found in Minnesota for the first time in several
years.
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The winter wheat harvest is underway from South Carolina to southern Kansas.
Most of the small grains in the U.S. are 1 to 2 weeks ahead of normal crop
maturity.
Wheat stem rust
There have been no new reports of wheat stem rust since CRB #5.
Wheat leaf rust
During the second week in June, leaf rust severities of trace to 5% were
reported in wheat fields from northeastern Missouri to northwestern Ohio and
southern Michigan (Fig. 1). On June 10, on flag leaves, leaf rust severity
ratings of trace to 5% were recorded on most of the wheat varieties in
northeastern Indiana plots, while 60% severities were recorded on a few
susceptible lines. Throughout this area, leaf rust was more severe than last
year, because of the large amounts of leaf rust inoculum that arrived from
the southern U.S. and because in May the weather was warmer and wetter than
normal.
By the second week in June, the last of the green leaves dried up in northern
Kansas. The hot dry winds at the end of May caused premature ripening of
wheat in central Kansas. Leaf rust developed late, but still managed to kill
the flag leaves of susceptible cultivars during the soft dough stage
throughout eastern and central Kansas. Some of the commonly grown varieties
like Jagger, had significant amounts of rust (50% severity at early dough).
During the second week in June, leaf rust severities of trace to 5% were
reported on flag leaves of winter wheat in a nursery in southeastern South
Dakota. On the lower leaves, leaf rust severities ranged as high as 40%. In
spring wheat, traces of leaf rust were observed on early planted lines at
Brookings, South Dakota. During the second week in June, trace to 20%
severities were found in winter wheat varietal plots in east central
Minnesota. Leaf rust severities of trace to 1% were observed on winter wheat
in south central Wisconsin in early June. Rust development is more severe
than last year in the northern wheat growing area.
In early May, low levels of leaf rust that overwintered were reported in the
snowbelt region east of Lake Ontario. In early June, traces of leaf rust
were observed in the winter wheat varietal plots at Ithaca, New York.
By the second week in June, wheat leaf rust was increasing throughout the
state of Washington. Rust severities were high in winter wheat plots at
Walla Walla and starting to increase in plots at Pullman in eastern
Washington and Mt. Vernon in western Washington.
The preliminary leaf rust race identifications for 1998 are shown in Table 1.
So far, there have been no major changes from 1997 in races which have been
identified
Table 1. Wheat leaf rust races identified through June 15, 1998
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Number of isolates
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Prt code Virulence formula* TX AL GA
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MBDL 1,3,17,10 7
MBRL 1,3,3ka,10,11,30 8 3 1
MDBL 1,3,10,24 3
MDRL 1,3,3ka,10,11,24,30 14 3
MCDL 1,3,10,17,26 19
MJBL 1,3,10,16,24 4
MFBL 1,3,10,24,26 2
MNRL 1,3,3ka,9,10,11,24,30 1
TBTL 1,2a,2c,3,3ka,10,11,17,30 1
TDBL 1,2a,2c,3,10,24 1
TDDL 1,2a,2c,3,10,17,24 2
TDRL 1,2a,2c,3,3ka,10,11,24,30 7
TFBL 1,2a,2c,3,10,24,26 8
TFRQ 1,2a,2c,3,3ka,10,11,18,24,26,30 1
TFTL 1,2a,2c,3,3ka,10,11,17,24,26,30 4
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Number of isolates 80 6 3
Number of collections 41 3 3
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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
During the second week in June, stripe rust severities of 60% were found in a
winter wheat plot at Rosemount, in east central Minnesota. Hot weather will
slow the stripe rust development.
By the second week in June, wheat stripe rust was widespread in the Pacific
Northwest. In susceptible winter wheat cultivars in plots near Pullman,
Washington, 100% severities were observed at heading to anthesis. Severities
of 90% were reported in eastern Washington fields of Westbred 470 near Walla
Walla. The rust is also developing in spring wheats. Farmers growing
Westbred 470 are spraying for the rust, while cultivars with high-
temperature, adult-plant resistance continue to provide durable resistance.
Oat stem rust
From oat stem rust collections made in early April in southern Texas the
common race NA-27 was identified and from collections made in southern
Alabama the NA-16 and NA-27 races were identified.
Oat crown rust
In early June, moderate aecial infections were found on buckthorn bushes in
south central and southeastern Wisconsin. By the second week in June, traces
of crown rust were found in southern Wisconsin fields.
By June 15, crown rust was severe on the lower leaves of oat growing near the
buckthorn bushes in the nursery on the University of Minnesota, St. Paul
campus, but little rust had spread to the upper leaves. Recent cool weather
limited crown rust development.
By the second week in June, crown rust had shown up on susceptible spreader
strips adjacent to buckthorn hedges, but had not spread to later planted
plots in southern Ontario, Canada because of extreme dry conditions. The
buckthorn was not heavily infected, but adequate to initiate a good
epiphytotic in the spreader strips.
Barley stem rust
No barley stem rust has been reported in the U.S. as of June 15.
Barley leaf rust
During the second week in June, barley leaf rust severities of 80% were
reported at the soft dough stage on some susceptible lines in a southern
Ontario, Canada nursery. Rust was just starting to increase on spring
barley.
In early June, barley leaf rust was increasing on spring barley at the late
jointing stage, near Mt. Vernon in western Washington.
Stripe rust on barley
In early June, stripe rust on barley was found throughout southeastern Oregon
and the state of Idaho. In a southwestern Idaho field, a 90% disease
severity at the milk stage, was reported and in a northern Idaho field a 20%
severity was reported, primarily on the lower leaves. Barley stripe rust is
increasing on spring barley near Pullman in eastern Washington and Mt. Vernon
in western Washington. At the present time, the only control recommended is
the use of a systemic fungicide, such as Tilt or Folicur.
Rye leaf rust
Traces of rye leaf rust were found in southern Minnesota in early June.
Rye stem rust
Rye stem rust has not been reported in the U.S. as of June 15.
Stem rust on Barberry
In early June, aecial infection was light on barberry in south central
Wisconsin and southeastern Minnesota. Moderately severe aecial infection was
found on barberry in Massachusetts.
Latest rust news
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page (http://www.crl.umn.edu) regularly.