Cereal Rust Bulletin
Fianl Report
Aug. 8, 2000
Issued by:
Cereal Disease Laboratory
U.S. Department of Agriculture
Agricultural Research Service
University of Minnesota
1551 Lindig St, St. Paul, MN 55108-6052
(612) 625-6299 FAX (651) 649-5054
markh@cdl.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 ³subscribe² in the message body (not subject line)
to: cereal-rust-survey-request@coafes.umn.edu
Reports from this mail list as well as all Cereal Rust Bulletins
are maintained on the CDL website (http://www.cdl.umn.edu/).
_________________________________________________________________
* Stem rust was common throughout the northern Great Plains on
wheat, barley and oat, but developed too late for major damage.
* Wheat leaf rust was less severe than in recent years except in
the northern Great Plains where it has been higher than average
for the last two years.
* Due to a mild winter and cool spring, stripe rust spread
throughout the Great Plains, Southeast and Midwest to an extent
not seen in 40 years.
* Oat crown rust was lighter than normal especially in the upper
Midwest.
_________________________________________________________________
WHEAT STEM RUST. Except for light infections in Texas, there were
few reports of stem rust in wheat fields in the southern U.S. in
2000. In mid-March, traces of wheat stem rust were found in soft
red winter wheats growing in plots in southern Texas at the Uvalde
experiment station.
By mid-April, wheat stem rust was severe in southern Texas plots
and light in central Texas plots. By the second week in April,
light amounts of stem rust were found on several entries in
central Louisiana wheat plots. During late April, wheat stem rust
was severe on a few susceptible cultivars in central Texas plots
and light in north central Texas plots. In southern Texas at
Uvalde, stem rust was severe throughout the plots. During the end
of April, traces of wheat stem rust were observed in southern
Louisiana plots.
In mid-May at the south central Kansas experiment station at
Hutchinson, traces of wheat stem rust were found on the cultivar
2137. During late May, foci of 20% severity were observed
scattered throughout a soft red winter wheat field in west central
Missouri, and traces were found in a south central Kansas hard red
winter wheat nursery. Light stem rust was observed on susceptible
wheats during harvest in northern Texas wheat plots in late May.
In mid-June, foci of stem rust were found in soft red winter wheat
fields in northeastern Missouri, east central Illinois, west
central Indiana, and south central Wisconsin. Rust severities
ranged from 1 to 20% in the center of the foci to traces at about
1 foot from the center. In eastern Nebraska, leaves of hard red
winter wheat were heavily infected, but stems were only slightly
infected. On June 18, traces of stem rust were found on the hard
red winter wheat cultivar 2137 in southeastern North Dakota. Rust
pustules were on both the leaf blades and leaf sheaths, which is
unusual for stem rust except when the spores are rain deposited,
as likely occurred in the infections found in North Dakota and
those seen in Nebraska.
By late June, 20% stem rust severities were reported in plots of
susceptible winter wheat cultivars, e.g., 2174, in east central
South Dakota and east central Minnesota. In winter wheat fields
in northern Kansas and southern Nebraska, wheat stem rust
developed late and since most of the wheat cultivars were early
maturing they escaped the stem rust. The southern and central
Great Plains, where the winters were mild this year, provided
spores for susceptible wheats farther north. In much of the
northern Great Plains the temperatures in early June were near
normal and moisture levels were ideal for the spore infection
process to occur.
By the first week in July, trace-20% stem rust severities were
observed on the susceptible spring wheat varieties Baart and
Morocco in south central Minnesota and eastern South Dakota plots.
In the same south central Minnesota plots on June 22, only traces
were observed on Baart wheat. The rust development was due to
spores which were deposited with rains in early to mid-June.
During the third week in June, most of the stem rust development
was found on the leaves and by the first week in July, stem rust
was found on both leaves and stems.
In the third week of July, 10-40% stem rust severity ratings were
recorded on susceptible winter wheat cultivars like Norstar,
Seward, and Windstar in east central North Dakota plots. On the
susceptible spring wheat cultivar, Max, 40% severities were
reported at the soft dough plant growth stage in late July at the
east central North Dakota nursery. During the fourth week in
July, trace to 5% severities were reported on older susceptible
varieties like Baart, throughout plots in northwestern and central
Minnesota and 5-40% severities in the rust nursery in central
North Dakota. No wheat stem rust was observed by Cereal Disease
Lab staff when conducting surveys in spring wheat fields in the
upper Midwest this year.
As in 1999, the number of stem rust samples received at the Cereal
Disease Lab this year was twice the number in recent years. The
increased severity of stem rust can be attributed to the large
amount of inoculum produced on susceptible winter wheat cultivars,
e.g. 2137, farther south in the Central Plains and to the
temperature and moisture, which were ideal for stem rust infection
in the Northern Plains this year. If current spring wheat
cultivars were susceptible to stem rust, a serious epidemic with
substantial yield losses would have occurred.
To date, races Pgt-QCCJ, QCCS, QCMS, QCRS, RCMS and RCRS (Table
1) are the most common races identified from collections made in
the southern U.S. The QCCJ race is virulent on barley cultivars
with the Rpg1 (T) gene for resistance. The RCRS race was the most
commonly identified race in 1998 and 1999. In 1999, races QCCS
and QCMS were only found in North Dakota and this year they have
been identified from Texas rust collections.
WHEAT LEAF RUST. Southern Plains - In early February, light
amounts of leaf rust were found on the susceptible cultivar TAM107
in central Texas plots, but near drought conditions throughout
much of Texas kept rust development to a minimum. In early March,
leaf rust increased rapidly in south and north central Texas
wherever moisture was present for rust infection to occur. By the
third week in March, 10-40% severity rust readings were observed
on the lower leaves of susceptible cultivars in southern Texas at
the experiment stations in Uvalde and Beeville.
During the third week in April, leaf rust was severe in plots from
south to north Texas on susceptible cultivars, but rust
development was light in Texas farm fields (Fig. 1). The mild
winter and rainfall in late March and early April contributed to
the rust development in much of this area. In mid-April, leaf
rust severities of 60% were observed in central Texas plots of
TAM-107.
In early April, leaf rust was light in fields throughout Oklahoma.
In central Oklahoma plots, 10-30% severities were observed on the
lower to mid leaves.
During the last week of April, wheat leaf rust severities in north
central Texas and southern Oklahoma plots ranged from trace to
80%. Severities were as high as 70% in fields where rust
overwintered. By early May, rust increased throughout Oklahoma.
The mild winter and rainfall in late March and early April
contributed to the rust development in most of this area. This
region provided leaf rust inoculum for wheat grown farther north.
Central Plains - Leaf rust was light throughout south central
Kansas in early April. During the third week in April, in south
central Kansas plots, 10% severities were observed on the mid
leaves. In Kansas, only light amounts of leaf rust overwintered,
which is the same as in 1998 and 1999.
In early May, traces of leaf rust were found on the flag leaves of
susceptible wheat cultivars in fields in the southern half of
Kansas (Fig. 1). This is similar to leaf rust development last
year.
By the third week in May, 100% severities were observed on
susceptible cultivars in south central Kansas plots. Some
cultivars, e.g., Jagger, had 30% severities in fields, but leaf
rust was light in fields of 2174. Rust was light in north central
Kansas because of the dry conditions which prevented rust
infections during early May.
During the last week in May, trace to 80% severities were reported
on winter wheat cultivars in south central Kansas nurseries. In
fields in the same area, 40% severities were observed on
susceptible cultivars like Jagger, but on most of the other
cultivars severities were 1% or less. In north central Kansas and
west central Missouri, 20% severities were observed on susceptible
cultivars at the early berry stage. In late May, in south central
Kansas spring wheat plots (i.e., 2375), trace to 20% severities
were observed at the 1/4 berry stage. During April and early May,
leaf rust development was slowed throughout the central Great
Plains because of moisture shortage, but with rain and dew in mid-
May conditions for leaf rust infection improved. However, near
the end of May, the hot windy conditions made conditions less than
ideal for rust development. In 2000 the overall estimated loss
due to leaf rust in Kansas was 2.9%, which is below the 10-year
average of 4.8%, but close to last year¹s estimate of 3.5%. Yield
losses were estimated from fungicide plot data, cultivar surveys,
cultivar disease ratings and disease surveys.
During late May, traces of leaf rust were found in southeastern
Nebraska winter wheat plots and fields.
Northern Plains - At Rosemount, Minnesota, viable leaf rust
pustules that had apparently overwintered were found on April 27
on lower leaves in hard red winter wheat plots.
On May 30, traces of leaf rust were observed on the leaves of
winter wheat cultivars in east central North Dakota plots. The
rust development in the North Dakota plots probably originated
from rust spores that were deposited with rain around the middle
of May. The timing of this rust development was the same as last
year.
During the first week in June, 10% leaf rust severities were
observed on the flag leaves of susceptible winter wheat cultivars
and traces on the lower leaves of susceptible spring wheats in
Rosemount, Minnesota plots.
By mid-June, 20% severities were reported on susceptible winter
wheat cultivars at the early boot stage in east central North
Dakota. In mid-June, trace to 15% severities were observed on
susceptible spring wheat cultivars in central North Dakota.
During the final week in June, leaf rust on winter wheat was
moderate in central and western South Dakota and moderate to
severe in eastern South Dakota. Susceptible cultivars like
Alliance, Jagger, TAM 107 and Rose had 100% severities at the soft
dough maturity stage in east central South Dakota varietal plots.
The rust infections in South Dakota probably originated from
inoculum sources in Oklahoma and Kansas. As in previous years
winter wheat flag leaves senesced because of leaf rust and hot
windy conditions throughout South Dakota.
In late June, susceptible winter wheat cultivars had leaf rust
severities ranging from 20-50% in southeastern North Dakota plots.
During the first week in July, leaf rust severities of 60% were
reported on the flag leaves of susceptible spring wheat cultivars,
e.g., 2375 and Oxen, in south central Minnesota plots. In fields,
severities ranged from trace to 10% on the lower leaves of spring
wheats in western Minnesota and eastern South Dakota. This year,
leaf rust was not as severe and concentrated in the Upper Midwest
as last year when 3-4% losses occurred in the Dakotas and
Minnesota. This year less rust inoculum arrived from the south,
but spring wheat cultivars currently grown are less resistant to
leaf rust than 10 years ago. However, one of the more susceptible
spring wheat cultivars, AC Barrie, was generally removed from
production in 2000.
In late July, trace-10% severities were found in spring wheat
fields and trace to 80% severities in plots throughout
northeastern Montana, central and northern North Dakota and
western Minnesota. Throughout northeastern North Dakota more
fields were sprayed for fungal diseases than in past years. This
year in southern North Dakota rust was normal but less than last
year. In the northern spring wheat growing area some losses are
expected, especially in late planted fields and in fields that
were not sprayed.
Canada - By late July, in fields not sprayed with fungicides,
trace to 5% severity was found on wheat in southeastern Manitoba.
Leaf rust infections in the south central area were lighter with
only trace amounts of leaf rust. Late planted wheat fields seeded
with susceptible varieties may experience significant yield
losses.
Southeast and East - In early February, light leaf rust was found
in susceptible spreader rows in southern Louisiana. Rust
development was slower starting than normal because of the lack of
moisture throughout the southern soft red winter wheat area. In
early March, wheat leaf rust was increasing throughout the state
of Louisiana and by late March severe leaf rust was observed in
the plots in southern Louisiana. By late March, leaf rust was
severe on susceptible cultivars in nurseries in west central
Mississippi, while most of the commercial fields in the area were
sprayed and did not have rust.
During late March, light leaf rust was found in plots of
susceptible lines in southwestern Georgia and the Panhandle of
Florida. By mid-April, plots of susceptible wheat had moderate
leaf rust infection and fields within 75 miles of the Gulf Coast
had light infection. Leaf rust development in much of the
Southeast was inhibited by drought conditions. Wheat plots in
central South Carolina had 30-50% leaf rust severities in mid
April. A few plots of susceptible soft red winter wheats in the
Southeast had 80% leaf rust severities by earl May, but fields
generally had trace to 20% severities. Fungicides were applied in
a few fields, e.g. Coker 9835, to control leaf rust. Dry weather
in the Southeast limited rust development, and fewer spores than
usual were available for spread to areas further north.
In late April, in Arkansas, leaf rust had increased where rust
overwintered. Some cultivars that were severely rusted in
previous years were resistant while other cultivars, e.g., Shiloh,
were susceptible, which indicates a change in the race population
in that area.
By the third week in May in northeastern Arkansas, leaf rust was
generally light in plots and fields but was severe on a few
cultivars, e.g., Shiloh. Leaf rust also was light in southwestern
Kentucky plots during the third week in May.
In most of the southeastern U.S., weather was drier and cooler
than normal through March and most of April and was a limiting
factor in rust development. In late April, frequent rains
occurred which were followed by rapid leaf rust increase on
susceptible cultivars. Because the crop matured so fast losses to
leaf rust were limited.
In North Carolina in 2000, wheat leaf rust was first observed in
the middle of March in breeding plots at Plymouth and Kinston.
The leaf rust infections were widely scattered on plots of
susceptible wheat lines, which indicated that infections may not
have overwintered in 2000 compared to 1999 when infections were
found in the middle of February and tended to be concentrated in
smaller areas. The severity of leaf rust infection on susceptible
lines increased slowly through the spring, reaching near 100% by
the second week of May.
In fields infections levels were generally light to moderate, due
to the cultivation of leaf rust resistant cultivars. Dry weather
in the first part of May also reduced rust severity. Infection
levels were heaviest in the coastal plain region, where the
majority of the wheat is grown in the state. In the Piedmont
region near Raleigh, very little rust could be found The cultivar
Coker 9663, which was widely grown in 2000 had little if any rust
infection in fields, or in nursery plots. Coker 9835 which is
also widely grown, had moderate to high levels (20-50%) in nursery
plots. Pioneer 2580 had moderate levels of rust infection in both
nursery plots and fields.
Wheat lines and cultivars with combinations of adult plant genes
Lr12 and Lr34 had a high level of resistance. Adult plant gene
Lr13 did not provide effective resistance, either singly or in
lines with other genes. Test lines of wheat with single genes
Lr9, 16, 17, 19, 21, 23, 24, 25, 26, 29, 33, 41,42 and 43 at
Kinston, NC showed useful resistance to leaf rust.
By late May, 5 to 80% leaf rust severities were reported on wheat
in nurseries in eastern Virginia.
In mid-June, trace levels of wheat leaf rust were common in wheat
fields of central and western New York. Both May and June were
characterized by above normal precipitation and below normal
temperatures.
Midwest - During late May, in central Indiana, leaf rust was
increasing on the upper leaves of plants on which Septoria had
destroyed the lower leaves.
By the second week in June, 40% leaf rust severities were reported
in plots of susceptible soft red winter wheat cultivars from
northeastern Missouri to northwestern Ohio and in fields
severities ranged from 0 to 10% (Fig. 1). In fields in
northwestern Ohio, 5% severities were noted on 20% of the wheat
plants at the 1/2 berry maturity stage.
In mid-June, traces levels of wheat leaf rust were common in wheat
fields in southern Wisconsin. Both May and June were
characterized by above normal precipitation and below normal
temperatures.
California - In early May, 20-80% leaf rust severities were
reported on wheat lines growing in southern California nurseries.
In mid-May, leaf rust severities were low in California commercial
wheat fields, but 50-100% severities were reported on a few lines
and varieties in nurseries in central and southern San Joaquin
Valley.
Pacific Northwest - In early July, wheat leaf rust was increasing
on spring wheats in eastern Washington fields and susceptible
wheats in nurseries had 60-70% severities.
Wheat Leaf Rust Virulence - The preliminary 2000 leaf rust race
identifications from collections made in the U.S. are presented in
Table 2. From the central and southern Plains rust collections
the most common races were M-races(virulent to Lr1,3,10,17,+).
Many of the MBDP and MCDP races were identified from rust
collections made from Jagger which is grown on significant acreage
in the southern and central Plains states. There also has been an
increase in the number of T-- races (virulent to Lr1, 2a,2c, 3,
+), particularly, an increase in T-- races with virulence to Lr9
and 10 in the southern soft red winter wheat area. This Lr9 and
10 combination has rarely been found in past leaf rust surveys.
WHEAT STRIPE RUST. South - In early March, light amounts of
stripe rust were found in a wheat field in southern Louisiana. In
late March, light stripe rust was found in plots in northeastern
Louisiana.
In mid-March, stripe rust was widespread on the lower leaves and
upper leaves of several cultivars in northwestern Arkansas where
the rust had overwintered.
By the third week in April, wheat stripe rust was severe in
commercial fields throughout northwestern Louisiana.
During mid-April, stripe rust was increasing throughout the state
of Arkansas. Foci several hundred feet in diameter were found
where stripe rust had overwintered. More Tilt was sprayed this
year than in any of the last 5 years.
During late March, infections of stripe rust that had overwintered
were found on the lower leaves of soft red winter wheat cultivars
at the Uvalde,Texas experiment station.
By the third week in April, wheat stripe rust was severe in
commercial fields throughout northeastern Texas and northwestern
Louisiana. Entire fields were yellow from top to bottom and many
fields were abandoned because of stripe rust. Many fields were
sprayed with the fungicide Tilt which reduced yield loss. Late
maturing soft red winter wheat fields had high stripe rust
severities. The high level of stripe rust in March-April was due
to the mild winter which allowed wheat to start growing early and
more rust to overwinter. In the early spring there was good
moisture with cool nighttime temperatures which provided perfect
conditions for stripe rust development.
By late April, wheat stripe rust was severe from northeastern
Texas and southern Oklahoma to northeastern Arkansas. It has been
estimated there will be a 10% loss to wheat stripe rust in
northeastern Texas.
As of early May, stripe rust was still increasing in northern
Arkansas (Fig. 2) because there still had not been any prolonged
periods of hot weather, which usually stops stripe rust
development. This year, stripe rust was reported in a southern
Georgia nursery for the first time since 1974. In late April,
stripe rust was light in plots in northern Alabama. In west
central Mississippi plots where it was dry, wheat stripe rust was
more scattered and easier to evaluate than wheat leaf rust.
During the third week in May in northeastern Arkansas, active
stripe rust sporulation was observed in wheat plots and fields.
The crop matured fast and with the arrival of hot temperatures
stripe rust development stopped. By the third week in May, 50% of
the entries in northwestern Arkansas plots were either destroyed
by stripe rust or severely damaged.
In mid-May, stripe rust was found throughout Kansas. The mild
winter and cool spring were conducive for stripe rust development.
In south central Kansas plots, stripe rust was severe on a few of
the hard red winter cultivars, especially those with the 1B-1R
gene translocation, which indicated a possible virulence to Yr9.
Losses to wheat stripe rust in Kansas were estimated to be 0.05%.
Trace amounts of stripe rust were found in wheat breeding plots at
Brookings, South Dakota in mid-May. The wheat plots ranged from
late boot to heading stage.
In late May, stripe rust was observed throughout eastern Kansas,
northwestern Missouri and southeastern Nebraska fields. In south
central Kansas plots, severities ranged from traces to 60% while
in Nebraska fields, 1% severities were observed. This year in the
Great Plains the cool spring and nighttime temperatures, which
were in the low 50s, were favorable for stripe rust development.
However, the hot windy conditions the later part of May probably
disrupted much of the stripe rust development.
On June 8, light amounts of wheat stripe rust were found in soft
red winter wheat plots at Rosemount, Minnesota. Hot temperatures
that followed the initial rust sighting in the Minnesota plots may
have delayed the rust development, but cooler weather in mid-June
allowed further increase.
In mid-June, traces of wheat stripe rust were found on the
cultivar 2137 in southeastern North Dakota
During the second week in June, wheat stripe rust was found in a
northeastern Colorado field. Normally, stripe rust is found at
higher elevations in Colorado, i.e, San Luis Valley (7,500 ft) or
in the front range of the Rockies.
In late June, wheat stripe rust was widespread in central and
eastern South Dakota on winter wheat. In plots at Brookings, some
winter wheat plots had a high level of infection, e.g., 80% on
Siouxland. Traces of stripe rust were found easily in spring
wheat fields and nursery plots. In foci, 30% severities were
observed in some spring varieties and lines. By the later part of
the first week in July, stripe rust development had slowed in
South Dakota because of the hot temperatures during the day and
temperatures at night that were greater than 60 degrees.
By late July, traces of stripe rust were found in spring wheat
fields and 50% severities were reported in irrigated plots in
northeastern Montana. Traces of stripe rust were scattered
throughout northern North Dakota spring wheat fields and in plots
severities ranged from trace to 20% (e.g. McNeal and NorPro).
There was little yield loss to stripe rust in the northern Great
Plains.
Canada - In late July, trace to l5% stripe rust severities were
reported in spring wheat fields in southeastern and south central
areas of Manitoba. Due to the early planting of most cereal
fields this year and cooler than average June temperatures,
susceptible wheat varieties that were not sprayed with fungicides
experienced low levels of stripe rust infection and associated
yield losses. However, later planted fields avoided infection due
to higher July temperatures that impeded further development of
stripe rust.
Midwest - In central Indiana, light stripe rust was found in late
May in fields and in breeding nurseries where it was more severe.
By mid-June, wheat stripe rust development was extensive from
central Illinois to southwestern Michigan and severities ranged
from traces to 20%. This was the most widely dispersed stripe
rust development observed throughout the northern soft red winter
wheat area in at least 20 years. In the northern most locations
rust severities ranged from trace to 10% with large sporulating
pustules. At many of these locations stripe rust was found
together with leaf rust on the same leaf which could mean that
they developed from the same spore shower. Much of this stripe
rust development originated from spores produced farther south in
Texas, Arkansas, or adjacent states.
East - On May 9, a wheat stripe rust focus 1m in diameter, was
found in northwest Georgia. This is one of the first records of
stripe rust ever being found in north Georgia. In mid-May, traces
of stripe rust were found in plots in Blacksburg, Virginia. This
is one of the first reports of wheat stripe rust east of the
Appalachian mountains.
Wheat stripe rust this year was the most widespread throughout the
southern U.S. than has ever been reported (Fig. 2). Last year, no
stripe rust was reported in south central U.S., but two years ago
light amounts of wheat stripe rust were scattered from the lower
Mississippi Valley north to east central Minnesota. This year
stripe rust was found early because it overwintered in many areas
in the southern U.S., where the winter was milder than normal.
Furthermore, the spring weather has been cooler than normal,
favoring stripe rust development. It appears that there was a
large source of inoculum that arrived early in the southern U.S.
from Mexico. Preliminary data from the wheat stripe rust
collections indicate a shift in the stripe rust virulences from
1998 to 2000 in the southern U.S.
California - In mid-May, temperatures were cool and several storm
systems provided moisture that allowed stripe rust to continue to
increase in the Central Valley of California. There were reports
of wheat stripe rust at 100% severity in commercial fields of the
widely grown variety RSI 5 throughout the Sacramento Valley and
the northern part of the San Joaquin Valley. Cool spring weather
also allowed wheat stripe rust to increase in commercial fields of
several varieties in the central and southern portion of the San
Joaquin Valley. Severities of 100% were observed on breeding
lines and varieties in nurseries in this area.
Pacific Northwest - By mid-March, wheat stripe rust was increasing
in plots and fields in western Washington.
In mid-April, wheat stripe rust severities of 60% were reported on
susceptible winter wheat lines in the Skagit valley nursery in
western Washington.
During the first week in May, wheat stripe rust was prevalent
throughout the state of Washington. Stripe rust exceeded 70%
severity on susceptible winter wheat cultivars in northwestern
Washington.
By late May, in eastern Washington, stripe rust was starting to
increase in winter wheats and development was slower than normal
because of the dry conditions in early and mid-May which were not
conducive for rust development.
By late June, wheat stripe rust was starting to increase on spring
wheats in the Pacific Northwest, and the susceptible cultivars
were sprayed with fungicides. Rust losses were minimal, since
most of the cultivars have high temperature, adult plant
resistance.
OAT STEM RUST. In late March, stem rust was found in oat plots in
a southern Louisiana nursery. In mid-April, oat stem rust was
light in southern Louisiana nurseries. The oat stem rust
increased slowly because of the cooler than normal temperatures
during the first half of April. Rust development was much less
than last year, when rust killed many of the lines in the Baton
Rouge nursery by mid-April. During the first week in May, in
central Louisiana plots, oat stem rust developed to moderate
levels on susceptible cultivars that were not severely infected
with crown rust.
During the first week in May, oat stem rust overwintering foci
were found in plots in southern Georgia and southern Alabama. The
rust killed the oats in these plots and moved outward onto oat
growing around the infected foci.
In early April, oat stem rust was severe in southern Texas plots
and moderate in central Texas plots. Oat stem rust development
was equal to last year throughout the southern U.S.
In late May, traces of oat stem rust were observed on some
cultivars in a south central Kansas plot. In mid-June, trace to
40% stem rust severities were observed in oat plots at the berry
growth stage in northeastern Missouri. Oat acreage is limited in
the central Plains states, which reduces the rust inoculum for the
northern plains oat crop.
During late June, 1% oat stem rust severities were found in
commercial fields in south central Wisconsin and trace-5%
severities were reported in plots in south central Minnesota and
east central South Dakota. In general, oat stem rust was less
widespread than last year on the same date, throughout the
northern oat-growing area.
By late July, trace to 5% severities were observed in oat plots
from central Minnesota to central North Dakota. Losses to oat
stem rust will be minimal this year in the upper Midwest.
In late July, trace amounts of oat stem rust were found on
susceptible trap plots and wild oat in the southeastern and south
central areas of Manitoba. Many oat fields were sprayed with
fungicide this year, so losses due to rust infection are expected
to be light this year.
During the last week in April, traces of oat stem rust were found
on wild oat (Avena fatua) in a plot in Butte, California. On May
22, limited oat stem rust was found on wild oats in Sonoma County,
California.
OAT CROWN RUST. In early March, in south Texas plots, crown rust
infections were severe in susceptible plots and increased at a
rapid rate wherever moisture was present.
In early March, traces of oat crown rust were found in southern
Louisiana. In late March, in southern Louisiana, crown rust
increased in oat plots and some lines had severities as high as
60%. In late March, light amounts of crown rust were found in oat
plots along the Gulf Coast and some overwintering sites were
observed in locations like Headland, Alabama.
Oat crown rust increased rapidly during April from south central
Texas through southern Louisiana to southern Alabama. During mid-
April, crown rust was severe in these areas like last year, but
there was less crown rust further east. During mid-April, 50 -
75% crown rust severities were observed on susceptible oat plots
in the Baton Rouge, Louisiana nursery. By late April, crown rust
was severe in plots of susceptible cultivars and light in
commercial fields in the southern U.S. In much of this area, the
drier and cooler than normal weather during April was not
conducive to rust development. These southern areas provided some
inoculum for areas farther north.
In late May, traces of crown rust were found in oat plots in south
central Kansas and a collection of crown rust was made from Avena
fatua in Sonoma County, California.
In early May, pycnial infection was noted on buckthorn bushes at
St. Paul, Minnesota. In the buckthorn nursery, most of the pycnia
were found along the edge of the nursery rather than where the oat
telial straw was located. Therefore, the first pycnia observed
may be from f. sp. of Puccinia coronata that infect grasses rather
than oat. The timing of this pycnial development, in early May,
is near normal.
By the fourth week in May at St. Paul, Minnesota, a few uredinia
were found on the oat spreader rows in the buckthorn nursery. The
main flush of new pycnia did not appear in the buckthorn nursery
at St. Paul until early May. Cool weather delayed development of
aecia.
During late May, crown rust aecial infections were found on
buckthorn bushes in east central North Dakota.
By mid-June, oat in the buckthorn nursery in St. Paul, Minnesota,
had high levels (80% severities) of crown rust infection on lower
leaves and 5% severities on the upper leaves in the spreader row.
Traces of crown rust were found on oat in the other St. Paul
nurseries. In mid- June, trace levels of oat crown rust were
detected in south central Wisconsin fields.
In early July, 40% crown rust severities were observed on flag
leaves of oat in south central Minnesota plots, while in fields 1-
5% severities were found on the lower leaves. In early July,
crown rust had developed very slowly in east central South Dakota
and west central Minnesota nurseries with trace to 20% severities
on lower leaves of cultivars at the milk growth stage.
By late July, trace to 50% crown rust severities were observed in
varietal plots in eastern and central North Dakota. In western
North Dakota plots rust was not found. Crown rust on oat was
lighter than in previous years except on susceptible cultivars.
On wild oat(Avena fatua) plants in west central Minnesota, 80%
severities were common while in northwestern North Dakota only
traces of crown rust were present. Crown rust losses in the
northern oat-growing area were less than the average of the past 5
years.
During the third week in May, aecia were observed on buckthorn on
the Cornell University campus in New York. In mid-July, severe
rust was reported in field of a susceptible cultivar, but in
general losses to crown rust were light in the eastern U.S.
In late June, crown rust severities were more severe and
infections earlier than normal on susceptible oat yield plots at
Guelph, Canada.
By late July, trace to 5% levels of crown rust were found on wild
oat (Avena fatua) and susceptible trap plots in the southeastern
and south central areas of Manitoba. Aecial infections on
buckthorn were heavier in July than has been found in recent
years. Crown rust was severe with up to 70% severities on wild
oat in experimental plots at the University of Manitoba, which is
adjacent to the Boyne River where buckthorn is found. The
cultivar Triple Crown with Pc48 had trace to 10% crown rust
severities in plots adjacent to the wild oat plots.
As of the middle of June, when oat crown rust virulence tests were
suspended for the summer, 40 isolates from Texas and 18 isolates
from the Southeast had been tested. Among these isolates 41
different races were identified with the standard set of 16
differentials. As in 1999, the LB-- and LQ-- race groups were
most common, accounting for nearly half the isolates. LB-
indicates virulence on Pc40 and avirulence on Pc38, 39, 45, 46,
48, 50, and 68. LQ- indicates virulence on Pc38, 38, and 40 and
avirulence on Pc45, 46, 48, 50, and 68. Frequencies of virulence
on the extended set of differentials are shown in Table 3.
Virulence to Pc68 was found in one isolate each in Texas and
Alabama. No isolates were identified with virulence to Pc45, 53,
62, TAM-O-393, or Vista.
BARLEY STEM RUST. In early April, a barley stem rust collection
was made in the Uvalde, Texas plots. Stem rust on barley rarely
occurs in the southern U.S.
In early July, 5% stem rust severities were observed on 10% of the
plants of the 2-row barley Hypana, in west and south central
Minnesota plots. No stem rust was found on barleys with the T-
gene, e.g., Robust.
In mid-July, 10% stem rust severities were reported on wild barley
(Hordeum jubatum) growing alongside the roadway in eastern South
Dakota and west central Minnesota. The last 2 years, stem rust
observed on wild barley has been very extensive throughout the
northern Great Plains. The rust developed early on the wild
barley because of the early spring and resulting earlier maturity
of the wild barley. In general, barleys are more susceptible to
stem rust as they mature. If current spring wheat cultivars were
more susceptible to stem rust, the stem rust on wild barley could
be a significant source of inoculum and substantial yield losses
would occur.
In late July, 70% severities were observed on 6-rowed barleys
(e.g. Bowman) in east central South Dakota plots. During late
July, traces of stem rust were found on 2 & 6 row barleys growing
in plots from northeastern Montana to west central Minnesota and
none was found in commercial fields. There was less stem rust
observed on barleys this year in the northern Great Plains which
may be due to less QCCJ (stem rust race which infects Rpg (T gene)
found in the southern U.S. compared to 1999 (Table 1).
In late July, trace amounts of stem rust were found on wild barley
in both the southeastern and south central regions of Manitoba.
STRIPE RUST ON BARLEY. In early April, stripe rust was found on
winter barley cultivars and experimental lines in plots in
Corvallis, Oregon.
In mid-April, barley stripe rust was severe on susceptible lines
and crosses in a nursery in the Sacramento Valley of California.
In mid-April, stripe rust severities of 20% were reported on
susceptible winter barley lines in the Skagit Valley nursery in
western Washington.
By early May, barley stripe rust was observed in nurseries in the
Sacramento and San Joaquin Valleys of California with severities
of 80-100% on susceptible cultivars. In northwestern Washington,
70% severities were reported on susceptible winter barley
cultivars at the late jointing stage.
By mid-May, barley stripe rust increased throughout the Central
Valley of California reaching 100% severities on susceptible
varieties and breeding lines at the soft-medium dough stage. In a
large screening nursery (3000 entries) at Davis, California, 33%
of the entries were rated at 100% severity and 50% were rated at
50% severity.
In late May, in eastern Washington, barley stripe rust increased,
but development was slower than normal because of the dry
conditions in early and mid-May. By late June, stripe rust on
barley was starting to increase on spring barley in eastern
Washington and susceptible cultivars were rated from 20 to 50% in
plots. In the Pacific Northwest barleys susceptible to stripe
rust were sprayed with fungicides this year, so losses to rust
infection were light this year.
BARLEY LEAF RUST. In early April, light barley leaf rust was
found in plots at Uvalde, Texas.
In early July, 40% severities were reported on lower leaves in
spring barley plots in south and east central Minnesota and east
central South Dakota.
In late July, traces of barley leaf rust were found in plots in
central Minnesota. Losses to barley leaf rust in the U.S. were
minimal this year.
By the second week in May in Ontario, Canada, barley leaf rust was
found on susceptible winter barley plots where the rust had
overwintered. In late June, barley leaf rust was moderate on
winter barley yield plots and was starting to appear on
susceptible spring barley near winter barley strips at the Guelph,
Canada research station.
During late March, leaf rust (Uromyces hordeinus) on little
barley (Hordeum pusillum) was found along the Gulf Coast of the
U.S.
BARLEY CROWN RUST. In mid-June, traces of crown rust were
observed on barley near the buckthorn nurseries at Fargo, North
Dakota and St. Paul, Minnesota.
In late June, traces of crown rust were found in plots and fields
in eastern South Dakota and in south central and east central
Minnesota plots.
RYE STEM RUST. During late April, 10% rye stem rust severities
were reported in a central Texas plot.
In late July, traces of stem rust were found in Minnesota rust
detection plots of Prolific rye. In late July, resistant and
susceptible plant mixtures (10-20% severities) were observed on
winter ryes in an east central North Dakota nursery.
RYE LEAF RUST. During late March, 20-50% rye leaf rust severities
were observed on rye growing in plots within 75 miles of the Gulf
Coast in Alabama and Florida.
In late April, 60% rye leaf rust severities were reported on
cultivars throughout plots in the southeastern U.S.
In late May, 5% leaf rust severities were observed on rye in a
south central Kansas field.
In mid-June, 40% leaf rust severities were reported in a rye field
in northwestern Ohio.
By early July, 40% leaf rust severities were found on upper leaves
of spring rye in plots in southern and west central Minnesota. In
late July, 50% severities were reported on susceptible spring ryes
in north central Minnesota.
STEM RUST ON BARBERRY. During the second week in May and mid-
June, stem rust aecial infections were found on susceptible
barberry bushes in south central Wisconsin and southeastern
Minnesota.
This is the last issue of the Cereal Rust Bulletin for the 1999-
2000 growing season. I would like to thank all of those who
helped with the bulletin this year, especially Mark E. Hughes who
coordinates its distribution through the CDL website
(http://www.cdl.umn.edu), email (markh@cdl.umn.edu) and the post.
Any reports of rust that you found in your area were appreciated
and this information was added on our web page and Cereal Rust
Bulletins.
- David L. Long (davidl@cdl.umn.edu)
Table 1. Preliminary identification of wheat stem rust races identified
through August 4, 2000
Number of Isolates
Pgt-code Texas Louisiana Missouri
QCCJ 7
QCCL 1
QCCS 7 6
QCMJ 2
QCMS 26 2
QCRS 15
QTHS 1
RCMS 12 3
RCRS 8
RKQQ 1
RKRS 1
Table 2a. Preliminary identification of wheat leaf rust races identified
through August 4, 2000
Pt Number of isolates by state
code* Virulence formula** AL AR CA FL GA IL IN KS LA MI MN
FBGD 2c,3,11,14a 1
FBMT 2c,3,3ka,10,14a,18,30,B 2 4
FCMT 2c,3,3ka,10,14a,18,26,30,B 2
KFRS 2a,2c,3,3ka,10,11,14a,18,24,26,30 1
LBBL 1,10 1
MBBN 1,3,10,14a 1
MBDN 1,3,10,14a,17 4
MBDP 1,3,10,14a,17,B 2 5 67
MBGN 1,3,10,11,14a 3 1
MBRL 1,3,3ka,10,11,30 2 1
MBRN 1,3,3ka,10,11,14a,30 2
MBRR 1,3,3ka,10,11,18,30,B 2
MBRS 1,3,3ka,10,11,14a,18,30 8 2 1 1
MCDP 1,3,10,14a,17,26,B 1 2 4 10 2 6
MCRJ 1,3,3ka,11,14a,18,26,30 4
MCRN 1,3,3ka,10,11,14a,26,30 1
MCRS 1,3,3ka,10,11,14a,18,26,30 43 2 5 2 5 20 2
MCTP 1,3,3ka,10,11,14a,17,26,30,B 3
MDBP 1,3,10,14a,24,B 1
MDMN 1,3,3ka,10,14a,24,30 4
MDRN 1,3,3ka,10,11,14a,24,30 4
MDRS 1,3,3ka,10,11,14a,18,24,30 2
MNRS 1,3,3ka,9,10,11,14a,18,24,30 1
PCRT 1,2c,3,3ka,10,11,14a,18,26,30,B 2
TBBN 1,2a,2c,3,10,14a 2
TBBS 1,2a,2c,3,10,14a,18 1
TBHT 1,2a,2c,3,10,11,14a,18,30,B 2
TBRP 1,2a,2c,3,3ka,10,11,14a,30,B 1
TBRT 1,2a,2c,3,3ka,10,11,14a,18,30,B 2
TCBN 1,2a,2c,3,10,14a,26 4 4
TCBP 1,2a,2c,3,10,14a,26,B 2 6
TCBT 1,2a,2c,3,10,14a,18,26,B 2
TCDP 1,2a,2c,3,10,14a,17,26,B 1
TCMN 1,2a,2c,3,3ka,10,14a,26,30 2
TCRN 1,2a,2c,3,3ka,10,11,14a,26,30 10 2 10
TCRS 1,2a,2c,3,3ka,10,11,14a,18,26,30 2
TDRN 1,2a,2c,3,3ka,10,11,14a,24,30 2
TFDN 1,2a,2c,3,10,14a,17,24,26 2
TFRN 1,2a,2c,3,3ka,10,11,14a,24,26,30 1 2
TLBN 1,2a,2c,3,9,10,14a 2
TLBP 1,2a,2c,3,9,10,14a,B 1
TLGJ 1,2a,2c,3,9,11,14a,18 5 4 10 4
TLGN 1,2a,2c,3,9,10,11,14a 2 5 9
TLGS 1,2a,2c,3,9,10,11,14a,18 4
TLRJ 1,2a,2c,3,3ka,9,11,14a,18,30 2
TNBN 1,2a,2c,3,9,10,14a,24 2
TNMN 1,2a,2c,3,3ka,9,10,14a,24,30 2 6
TNMS 1,2a,2c,3,3ka,9,10,14a,18,24,30 2
TNRN 1,2a,2c,3,3ka,9,10,11,14a,24,30 2 13
Number of isolates 84 12 6 15 21 2 27 89 103 4 11
Number of collections 46 7 4 11 15 1 19 55 53 2 7 Table 2b. Preliminary identification of wheat leaf rust races identified
through August 4, 2000
Pt Number of isolates by state
code*Virulence formula2 MO MS NC ND OH OK SC SD TX VA WI
LBBS 1,10,14a,18 2
LCRS 1,3ka,10,11,14a,18,26,30 2
MBBN 1,3,10,14a 2
MBDL 1,3,10,17 2
MBDP 1,3,10,14a,17,B 4 2 1 4 4 34 1
MBMP 1,3,3ka,10,14a,30,B 2
MBRN 1,3,3ka,10,11,14a,30 7 2
MBRS 1,3,3ka,10,11,14a,18,30 1 35 2 2
MCBP 1,3,10,14a,26,B 4
MCDF 1,3,14a,17,26,B 1
MCDP 1,3,10,14a,17,26,B 8 2 7
MCMN 1,3,3ka,10,14a,26,30 1 2
MCMT 1,3,3ka,10,14a,18,26,30,B 2
MCRS 1,3,3ka,10,11,14a,18,26,30 21 4
MCRT 1,3,3ka,10,11,14a,18,26,30,B 4
MDGN 1,3,10,11,14a,24 2
MDMN 1,3,3ka,10,14a,24,30 2
MFMN 1,3,3ka,10,14a,24,26,30 1
MLBN 1,3,9,10,14a 2
PCRT 1,2c,3,3ka,10,11,14a,18,26,30,B 2
TBBN 1,2a,2c,3,10,14a 2 5
TBDN 1,2a,2c,3,10,14a,17 2
TBRT 1,2a,2c,3,3ka,10,11,14a,18,30,B 2 1
TCDP 1,2a,2c,3,10,14a,17,26,B 6
TCMN 1,2a,2c,3,3ka,10,14a,26,30 2 9 1
TCMP 1,2a,2c,3,3ka,10,14a,26,30,B 5
TCMS 1,2a,2c,3,3ka,10,14a,18,26,30 2
TCRN 1,2a,2c,3,3ka,10,11,14a,26,30 2 2 6
TCRS 1,2a,2c,3,3ka,10,11,14a,18,26,30 2 2
TCRT 1,2a,2c,3,3ka,10,11,14a,18,26,30,B 1 10
TDBN 1,2a,2c,3,10,14a,24 2
TDBT 1,2a,2c,3,10,14a,18,24,B 1
TFBN 1,2a,2c,3,10,14a,24,26 6
TFMN 1,2a,2c,3,3ka,10,14a,24,26,30 4
TFRN 1,2a,2c,3,3ka,10,11,14a,24,26,30 4
TLGJ 1,2a,2c,3,9,11,14a,18 2 18 3 2
TNBN 1,2a,2c,3,9,10,14a,24 4
TNMN 1,2a,2c,3,3ka,9,10,14a,24,30 1 7
TNRN 1,2a,2c,3,3ka,9,10,11,14a,24,30 2 12
TPGN 1,2a,2c,3,9,10,11,14a,24,26 2
Number of isolates 14 8 79 2 6 14 26 7 138 8 4
Number of collections 12 4 44 1 5 7 13 4 86 4 3
1 Race code, see Phytopathology 79:525-529.
2 Single gene resistances evaluated: Lr1,2a,2c,3,3ka,9,10,11,16,17,
18,24,26,30 and new single
gene additions evaluated 14a and B.
Table 3. Preliminary oat crown rust survey data for
2000
Percent virulent
AL & FL TX
Pc 14 94 100
Pc 35 39 93
Pc 36 72 68
Pc 38 78 50
Pc 39 39 50
Pc 40 94 100
Pc 45 17 3
Pc 46 22 25
Pc 48 0 0
Pc 50 6 5
Pc 51 67 80
Pc 52 0 0
Pc 53 0 25
Pc 54 61 20
Pc 55 39 43
Pc 56 61 60
Pc 57 35 33
Pc 58 17 18
Pc 59 28 67
Pc 60 61 90
Pc 61 67 63
Pc 62 0 0
Pc 63 50 45
Pc 64 0 28
Pc 67 89 50
Pc 68 6 3
Pc 70 47 60
Pc 71 39 48
H548 6 5
Dane 28 25
WI-X4361-9 39 40
TAM-O-386R 39 48
TAM-O-393 0 0
B604Xsel 11 23
Vista 0 0
No. isolates 18 40