CEREAL RUST BULLETIN
Report No. 7
June 18, 1997
Issued by:
CEREAL RUST LABORATORY
U.S. DEPARTMENT OF AGRICULTURE
AGRICULTURAL RESEARCH SERVICE
UNIVERSITY OF MINNESOTA
1551 Lindig St, ST. PAUL , MN 55108-6052
(612) 625-6299 FAX (612) 649-5054
Internet: markh@puccini.crl.umn.edu
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____________________________________________________________________________
€ Wheat stem rust foci were found in southeastern Illinois and northwestern
Kentucky.
€ Many new leaf rust races found in Texas.
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The small grain harvest is underway from South Carolina to southern Kansas.
Winter wheat is in good condition throughout most of the U.S. Last week, in
much of the northern small grain area, growing conditions were excellent,
except in parts of North Dakota and Minnesota where moisture was short .
Wheat stem rust
During the second week in June, wheat stem rust foci one meter in diameter
were found in southeastern Illinois and northwestern Kentucky fields at the
full berry growth stage. The stem rust severities in the middle of the foci
were rated 40%, while towards the outer edge of the 1 m foci, only traces were
observed. These foci developed from spores deposited in rain showers 4 weeks
ago. Similar foci of leaf rust infections were also found in these fields,
which developed from spores deposited in the same rain showers. The stem rust
that develops in this area will be a source of inoculum for susceptible
cultivars farther north.
Wheat leaf rust
During the second week in June, traces of leaf rust were found in wheat fields
from northeastern Missouri to southern Indiana. Throughout this area, leaf
rust was lighter than normal because the rust did not overwinter and during
May, rainfall was less than normal. During the second week in June, trace
leaf rust ratings were recorded on most of the wheat cultivars in southern
Indiana plots, while 20% severities were recorded on a few susceptible lines.
By the second week in June, 10% leaf rust severities were observed in wheat
fields in north central Kansas and south central Nebraska (Fig. 1). In
varietal plots in north central Kansas, 30% severities were common on
susceptible cultivars. In southwestern Nebraska, leaf rust was very light in
varietal plots and fields. Warm temperatures have pushed the crop to near
normal maturity.
In early June, traces of leaf rust were observed on lower leaves of wheat in
eastern Colorado.
During the second week in June, traces of leaf rust were found in central and
southeastern South Dakota fields and varietal plots. During the second week
in June, traces of leaf rust were found in winter wheat varietal plots in east
central Minnesota and southern Wisconsin. In early June, wheat leaf rust was increasing in the Skagit Valley of western
Washington. East of the Cascades, in eastern Washington, 1-2% severities were
reported in some fields. Leaf rust was also increasing in the Willamette
Valley of western Oregon.
The preliminary leaf rust race identifications for 1997 are shown in Table 1.
So far, 18 different races have been identified in Texas this year, which is
much more than normal. Some races like MBNL, MBTL and MFDL have not been
identified before in Texas.
TABLE 1. Wheat leaf rust races identified through June 17, 1997
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Number of isolates by state
Prt _________________________________________
code Virulence formula1 AL AR GA LA OK TX
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MBBL 1,3,10 1
MBGL 1,3,10,11 1
MBNL 1,3,3ka,10,17 4
MBRL 1,3,3ka,10,11,30 3 6 2 10
MBTL 1,3,3ka,10,11,17,30 1
MCBL 1,3,10,26 2
MCDL 1,3,10,17,26 17
MCRL 1,3,3ka,10,11,26,30 3
MCTL 1,3,3ka,10,11,17,26,30 2
MDBL 1,3,10,24 6
MDGL 1,3,10,11,24 1
MDRL 1,3,3ka,10,11,24,30 13
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
PNMQ 1,2c,3,3ka,9,10,18,24,30 4 1
TBBL 1,2a,2c,3,10 1 2
TDBL 1,2a,2c,3,10,24 2 12
TDRL 1,2a,2c,3,3ka,10,11,24,30 3
TFCL 1,2a,2c,3,10,24,26,30 1
TFBL 1,2a,2c,3,10,24,26 2
TFGL 1,2a,2c,3,10,11,24,26 4
TGBL 1,2a,2c,3,10,16 1
TLGG 1,2a,2c,3,9,11,18 2
_______________________________________________________________________
Number of isolates 3 12 9 2 2 85
Number of collections 2 6 6 1 1 47
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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 was very severe on many wheat
cultivars in the Skagit Valley of western Washington. In the Palouse area of
Washington, stripe rust ratings of 10-20% were found in wheat fields, but rust
losses will be minimal since most of the cultivars have good adult plant
resistance.
Oat stem rust
There have been no new reports of oat stem rust since the May 13th bulletin.
Oat crown rust
In early June, moderate to severe 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
17th, 20% crown rust severities were observed on lower leaves of oats growing
near the buckthorn bushes in the nursery on the University of Minnesota, St.
Paul campus.
In early June, aecial development was light on buckthorn bushes in eastern
South Dakota.
In early June, moderate levels of crown rust were found on buckthorn bushes in
the Ontario, Canada area.
Barley stem rust
There have been no new reports of barley stem rust since the last bulletin.
Barley leaf rust
By the second week in June, barley leaf rust was moderate to severe in the
Skagit Valley of western Washington.
Stripe rust on barley
In early June, barley stripe rust was severe on susceptible winter cultivars
at the full berry growth stage in the Skagit Valley of western Washington. As
of the second week in June, 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 the second week in June, aecial development was observed on barberry
bushes (alternate host for stem rust) in southeastern Minnesota.
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