CEREAL RUST BULLETIN
Report No. 8
July 21, 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
For the latest cereal rust news from the field, subscribe to the cereal-rust-
survey mail list. To subscribe, send an email message with the word
subscribe in the message body (not subject line) to:
cereal-rust-survey-request@coafes.umn.edu
Reports from this mail list and the Cereal Rust Bulletins are maintained on
the CRL web page (http://www.crl.umn.edu/).
_____________________________________________________________________________
* Wheat leaf rust in the northern plains is more severe than in recent years.
* Substantial losses to barley stripe rust are expected in the Pacific
Northwest.
_____________________________________________________________________________
The winter wheat harvest has begun from southwestern New York to northeastern
South Dakota. Spring-sown grains in the northern Great Plains are one to two
weeks ahead of normal crop development.
Wheat stem rust
In early July, traces of wheat stem rust were found in check plots of highly
susceptible spring wheat cultivars such as Baart, in eastern South Dakota. By
mid-July, traces of wheat stem rust were found in plots of the spring wheat
cultivar Max in southeastern North Dakota. In early July, trace to 20%
severities were observed in winter wheat plots in east central Minnesota and
southeastern North Dakota. This year there have been few reports of stem rust
in fields and nurseries and the number of rusted collections received at the
Cereal Disease Lab are 1/8 of normal.
By mid-July, scattered green plants in eastern Washington winter wheat plots
had 90% stem rust severities; traces of stem rust were found on susceptible
spring wheat lines. In the spring wheats, losses will be minimal since there
is adequate stem rust resistance.
Wheat leaf rust
As indicated in the previous Cereal Rust Bulletin, leaf rust was unusually
severe on winter wheat in the northern Great Plains this year. Although many
of the spring wheat cultivars in the northern plains are resistant to leaf
rust, some cases of higher than usual leaf rust severities have been reported.
In the past two weeks, in east central North Dakota, trace to 30% leaf rust
severities were observed on flag leaves of commercial spring wheat cultivars
(2375, Grandin, Barrier) at the anthesis stage. Losses are expected,
especially in late planted fields. In plots of susceptible spring wheats in
west central Minnesota, east centralSouth Dakota, and east central north
Dakota, 20-100% leaf rust severities were reported on flag leaves by mid-July.
In early July, 60% severities were observed in fields of winter wheat at the
mid-dough stage in southeastern North Dakota. In both North Dakota and South
Dakota, some yield losses from leaf rust are expected in winter wheat.
In early July, leaf rust was severe in the spring wheats in northeastern
Oregon. By mid-July, 90% severities were observed on susceptible spring
wheats growing in eastern Washington plots.
The preliminary leaf rust race identifications for 1998 are shown in Table 1.
The race identifications for Texas are from the southern part of the state
where there has been a significant increase in the number of T--- races that
have been found.
Table 1. Wheat leaf rust races identified through July 21, 1998
_________________________________________________________________________
Number of Isolates
____________________
Prt Code* Virulence Formula** TX AL GA LA
_________________________________________________________________________
MBBQ 1, 3, 10, 18 2
MBDL 1, 3, 17, 10 8
MBGQ 1, 3, 10, 11, 18 2
MBRL 1, 3, 3ka, 10, 11, 30 7 6 3
MCDL 1, 3, 10, 17, 26 24
MCRL 1, 3, 3ka, 10 ,11, 26, 30 1
MDBL 1, 3, 10, 24 4
MDRL 1, 3, 3ka, 10, 11, 24, 30 14 3
MFBL 1, 3, 10, 24, 26 2
MJBL 1, 3, 10, 16, 24 4
MNRL 1, 3, 3ka, 9, 10, 11, 24, 30 1
TCBL 1, 2a, 2c, 3, 10, 26 2
TCML 1, 2a, 2c, 3, 3ka, 10, 26, 30 1
TDBL 1, 2a, 2c, 3, 10, 24 1
TDDL 1, 2a, 2c, 3, 10, 17, 24 5
TDRL 1, 2a, 2c, 3, 3ka, 10, 11, 24, 30 8
TDTL 1, 2a, 2c, 3, 3ka, 10, 11, 17, 24, 30 2
TFBL 1, 2a, 2c, 3, 10, 24, 26 5
TFBQ 1, 2a, 2c, 3, 10, 18, 24, 26 1
TFGQ 1, 2a, 2c, 3, 10, 11, 18, 24, 26 2
TFRQ 1, 2a, 2c, 3, 3ka, 10, 11, 18, 24, 26, 30 1
TLGG 1, 2a, 2c, 3, 9, 11, 18 2
_________________________________________________________________________
Number of isolates 90 8 8 5
Number of collections 46 5 5 4
_________________________________________________________________________
*Prt code, see Phytopathology 79:525-529.
**Single gene resistances evaluated:
Lr1,2a,2c,3,3ka,9,10,11,16,17,18,24,26,30.
Wheat stripe rust
During mid-July, wheat stripe rust was increasing in spring wheat fields in
the Palouse region of Washington, but the adult plant resistance of commercial
cultivars should minimize losses. The most severe stripe rust in the Palouse
region was on the cultivar Vanna. This increased severity may be due to a new
race in the area.
Oat stem rust
In early July, trace to 5% severities of oat stem rust were reported in plots
in eastern South Dakota and in a southwestern Minnesota field. The last
report of oat stem rust in the Great Plains in 1998 was in early May in
central Texas.
Oat crown rust
During early July, crown rust severities ranged from trace to 5% in oat fields
and trace to 20% on flag leaves in plots in eastern South Dakota, west central
Minnesota and southern Wisconsin. By mid-July, 40-60% severities were
observed in plots in east central South Dakota. This year, throughout the
upper Midwest, the crown rust severities are much less than last year because
of the cooler than normal weather in early June and infections were less than
normal on buckthorn, the alternate host of oat crown rust.
Barley stem rust
The first report of barley stem rust this year was of traces in spring barley
plots in early July, in southwestern Minnesota and east central South Dakota.
During mid-July, traces of stem rust were found in southeastern North Dakota
and west central Minnesota spring barley plots. The number of barley stem rust
infections found is significantly down from the number found in the mid-1990s.
The decrease in barley stem rust infections is probably due to the decrease in
the percentage of QCCJ, which infects barley, in the race population (due to
the reduced acreage of QCCJ susceptible winter wheats in Kansas).
Barley leaf rust
In mid-July, trace to 10% leaf rust severities were observed in barley plots
in west central Minnesota, east central South Dakota and southeastern North
Dakota. In late June, 50% leaf rust severities were observed on barley in
central Wisconsin fields.
Stripe rust on barley
By early July, stripe rust on barley in the Pacific Northwest was severe on
susceptible spring-sown barleys from the intermountain area of northeastern
California, through northeastern Oregon to eastern Washington and northern
Idaho. In this area, 50% rust severities were recorded on Steptoe, but on
other cultivars with slow-rusting characteristics like Baroness 5% severities
were recorded. Throughout most the Pacific Northwest area, losses to barley
stripe rust will be much more severe than last year when 0.6% losses (4% in
Oregon, 0.5% in Washington and 01.% in Idaho) were recorded in this area.
Crown rust on barley
During the second week in July, trace to 1% crown rust severities were
observed on barley growing in southeastern North Dakota plots. Traces of
crown rust were found on barley in the buckthorn nursery in St. Paul, MN.
Throughout the upper Midwest this year crown rust on barley has been less
severe than in previous years.
Rye stem rust
The first report of rye stem rust this year was of trace amounts found in a
winter rye field in southeastern North Dakota.
Rye leaf rust
In early July, trace to 2% severities were reported on spring rye in plots and
fields in west central Minnesota and northwestern South Dakota.
Stem rust on barberry
There have been no new reports of stem rust on barberry since the last
bulletin.