A Database for Triticeae and Avena
CEREAL DISEASE LABORATORY
(formerly CEREAL RUST LABORATORY)
USDA-ARS, University of Minnesota, 1551 Lindig, St. Paul,
MN 55108, USA.
D.L. Long, J.A. Kolmer, M.E. Hughes, and L.A. Wanschura.
Stem rust. In 2002, the only reports of wheat stem rust
in the southern Great Plains were in late April, when light amounts
were found in plots in south Texas and southwestern Louisiana.
In late May, traces of stem rust were found on wheat in a field
and plot of the cultivar 2137 in central Kansas.
In the last week in June, traces of stem rust were observed
on susceptible winter wheat cultivars in central and eastcentral
South Dakota and southeastern North Dakota plots. In much of the
northern Great Plains, high temperatures and dry conditions limited
stem rust development.
In the third week in July, the susceptible spring wheat cultivars
Baart and Max had trace-20 % stem rust severities in southern
Minnesota, eastcentral South Dakota, and southeastern North Dakota
plots. At the end of July HRWW fields had traces of stem rust
in westcentral Wisconsin and northeastern South Dakota. In late
July, susceptible spring wheat plots and fields in central North
Dakota had 30 % severities.
Much of the early stem rust development in the northern plains
was due to spores deposited with rains in mid-June. The stem rust
infections can be attributed to inoculum produced on winter wheat
cultivars in the southern Great Plains and to the warm temperatures
and high moisture conditions, which were ideal for stem rust infection
in some areas of the northern plains. If current spring wheat
cultivars were susceptible to stem rust, a serious epidemic with
substantial yield losses would have occurred.
In late July, traces of wheat stem rust were found in fields
and disease nurseries in western Washington.
Stem rust race virulence. Race QCCJ (Table 1) is the
most common stem rust race identified from collections made in
the U.S. in 2002. This race is virulent on barley cultivars with
the Rpg1 (T) gene for resistance. QCCJ and most of the
other stem rust races identified in 2002 are avirulent to most
wheat cultivars. However, a single isolate of TPMK and two isolates
of TTTT were collected from susceptible wheat plots in Minnesota.
These races have more virulence to rust resistance genes in wheat.
TPMK and TTTT races have survived at low levels in the U.S.
Table 1. Races of Puccinia graminis
f. sp. tritici identified from wheat in 2002. Pgt race
code after Roelfs and Martens (Phytopathology 78:526-533). Set
four consists of Sr9a, 9d, 10, and Tmp.
Wheat leaf rust. Southern Plains. In early January,
traces of leaf rust were found in a nursery in central Texas and
by the second week in February 80-100 % severities were on lower
leaves and 30 % severities on upper leaves. Freezing temperatures
in early March damaged leaves and destroyed rust infected leaf
tissue. Drier and cooler weather in March slowed leaf rust development
throughout the southern U.S.
In early April, leaf rust was light in fields but severe on
susceptible cultivars in nursery plots from central Texas to Georgia.
In early April, sufficient moisture in central and southern Texas
allowed leaf rust to increase to 70 % severity on flag leaves
in plots at College Station and McGregor. At both locations in
Texas, cultivars that have Lr9 (Lockett) or Lr41
(Thunderbolt) had 70 % leaf rust severities. In drier areas of
west Texas, only 5-10 % severities were on lower leaves.
In mid-April, leaf rust was found in fields in trace to light
amounts and was severe on susceptible cultivars in plots from
central Texas to South Carolina. In early May fields in central
Texas, had 60 % rust severities, but the crop rapidly matured,
which limited any additional infections. In early May, leaf rust
was light in north Texas fields.
In the second week in March, light amounts of leaf rust were
in fields in central Oklahoma. In late March, only traces of leaf
rust were found in fields throughout Oklahoma. In early May, leaf
rust was light in fields and severe on susceptible cultivars in
plots from north central Oklahoma to central Alabama (Figure 1). In mid-May, leaf rust was severe
in plots and fields in central Oklahoma, but the crop was near
maturity, which reduced losses.
Central Plains. In mid-May, leaf rust in Kansas was
common on the flag leaves of susceptible cultivars in the south
central area and light in the northern part of the state.
In the last week in May, leaf rust was severe in plots and
fields of susceptible cultivars from central Kansas to westcentral
Missouri. In fields of Jagger wheat, at the late berry stage in
south central Kansas, there were 60 % severities, whereas Jagger
in northeast Kansas had 5 % severities. In central Kansas plots,
rust severities ranged from trace to 60 %. In late May, plots
at Lincoln, Nebraska, had light leaf rust infections.
In late May, leaf rust severities were 40 % on Ae. cylindrica
(goatgrass) growing in the roadsides in north central Oklahoma
and southcentral Kansas. In 2001 in the same areas, high levels
of stripe rust were found on goatgrass.
Leaf rust was severe in the southern part of Kansas in late
May. In the second week of June in southeastern Nebraska fields,
leaf rust incidence ranged from 30 to 100 %. Drought-like conditions
in much of Nebraska slowed leaf rust development for the remainder
of the season.
Northern Plains. In mid-June, light infections of leaf
rust were on flag leaves of HRWW in eastcentral South Dakota.
In the third week in June, 10 % leaf rust severities were on
susceptible winter wheats at anthesis in eastcentral Minnesota
plots. Traces of leaf rust were found in two fields in northwestern
Minnesota in the third week of June. Weather conditions were ideal
for rust infection throughout Minnesota in June.
In the last week in June, rust severities were 60 % on susceptible
winter wheat cultivars in east central and southcentral Minnesota
plots. During the last week in June, leaf rust on winter wheat
was light in central and eastern areas of South Dakota. On a few
susceptible cultivars like Jagger and Alliance, leaf rust severities
reached 30 %.
The majority of cultivars had only trace levels of infections
on the flag leaves. In early June, leaf rust was more severe in
Minnesota than in South Dakota since moisture conditions were
more favorable for rust in Minnesota. In the last week of June,
lower leaves (flag-2) of susceptible spring wheat cultivars had
severities of 40 % in southern Minnesota plots. In most of the
spring wheat cultivars only traces of rust were observed at this
During the fourth week of June, winter wheat plots in eastcentral
North Dakota had trace to 20 % rust severities. In the same area,
traces of leaf rust were common in fields of spring wheats. In
the Fargo, North Dakota nursery, the susceptible cultivar Thatcher
had 30 % rust severity. In mid-July, durum lines at the Carrington
research center in central North Dakota had 30 % leaf rust severities.
In the third week in July, spring wheat fields had trace-40
% leaf severities in plots in southeastern North Dakota and westcentral
and southern Minnesota. In early August, leaf rust was present
at high severity in the Red River Valley of Minnesota and North
Dakota. In many wheat fields the leaves dried prematurely due
to the heavy leaf rust infections combined with high temperatures.
Many wheat fields were sprayed with fungicide to reduce leaf rust
severities. In the Red River Valley the commonly grown wheat cultivars
had 40 % severity levels of leaf rust. High levels of leaf rust
were in fields in central and southeastern North Dakota. In the
northern tier of counties of North Dakota leaf rust was at reduced
levels due to very dry conditions. The wheat in this area was
in poor condition due to drought stress.
Most of the spring wheat cultivars currently grown are moderately
susceptible to leaf rust. Significant economic losses due to leaf
rust occurred in northwestern Minnesota and eastern North Dakota
Southeast. In mid-December 2001, light infections of
leaf rust development were uniform on lower leaves in a northeastern
Arkansas wheat field. In mid-January, light leaf rust infections
were observed on entries in a nursery in southwestern Arkansas.
In mid-February, light infections of leaf rust were found throughout
Arkansas in plots and fields. In the third week in February, infections
that overwintered were observed in northwestern Arkansas and in
plots of wheat in southwestern Arkansas. Because of the cold weather
in mid-March, there were no signs of leaf rust in northwestern
Arkansas wheat plots. In the last week in April, northeastern
Arkansas wheat plots had 10 % leaf rust severities and fields
had trace levels of infection. In late January, leaf rust was
reported in northeastern Louisiana plots. In mid-February, susceptible
cultivars in southern Louisiana had 20 % leaf rust severities.
During the second week in February, light amounts of leaf rust
were found on the cultivar Coker 9835 in a southcentral Georgia
nursery. In late February, rust levels were severe in the vicinity
of the initial focus indicating this was a likely overwintering
In mid-April, from northeastern Louisiana through Alabama and
Georgia to North Carolina, trace to light amounts of leaf rust
were observed in wheat plots. Leaf rust was widely present in
at least trace amounts throughout the winter wheat area of the
southern plains and the southeastern states.
In early May, from central Louisiana to central Alabama, susceptible
cultivars had 60 % leaf rust severities and resistant cultivars
had trace levels of infection in nursery plots. In some locations,
like eastcentral Alabama, where conditions were drier, susceptible
cultivars had leaf rust severities of 10-20 %. In 2002, leaf rust
was scattered and more severe than 2001 throughout the southeastern
winter wheat area of the U.S.
East. In mid-December, leaf rust was easily found on
the cultivar Saluda at Kinston, North Carolina. In mid-May, moderately
severe leaf rust was reported in eastern Virginia plots. In late
May, light leaf rust was reported in Blacksburg (western Virginia)
plots. In early June, susceptible cultivars in a nursery in western
Virginia and east central Maryland had 50-75 % leaf rust severities.
Traces of leaf rust were found in central New York fields in mid-June.
In mid-June, light leaf rust was observed in southwestern Ontario.
In 2002, leaf rust was observed throughout the eastern SRWW area.
Ohio Valley. In the second week in June, plots of SRWW
had trace-40 % leaf rust severities and traces in fields from
northeastern Missouri to northwestern Ohio (Figure 1) at the early to late berry maturity
stage. One field of susceptible wheat in northwestern Ohio had
60 % severities.
California. In early May, wheat fields in the Sacramento
Valley of California had 75 % leaf rust severities. Rust development
was reduced in California this year because of the dry conditions
in March and April.
In mid-May, leaf rust of wheat had spread throughout the Central
Valley of California. In the southern San Joaquin Valley, lines
and cultivars in nurseries had 40 % severities. Leaf rust was
also found on a few durum wheat cultivars and lines and moderate
severity was reported on one triticale cultivar. During the third
week in May, leaf rust was severe on flag leaves in most commercial
wheat fields throughout the Sacramento Valley, obscuring the stripe
rust that occurred earlier in the season on some of the same cultivars
in the region.
Washington. In mid-July, wheat leaf rust was increasing
on spring wheats in eastern Washington fields and susceptible
wheats in nurseries had 10-20 % severities. In late July, traces
of leaf rust were found in commercial fields. Yield losses due
to leaf rust were minimal in the PNW this year.
Wheat leaf rust virulence. The 2002 leaf rust race identifications
from the most common races identified are presented in Table 2
and Table 3. A total
of 52 races were found in the U.S. in 2002. From the central and
southern Plains the most common races were M-B- (virulent to Lr1,
Lr3, Lr10, Lr17, +) (Table 3). Many of the MBDS and MCDS races
were identified from collections made from Jagger, which is widely
grown in the southern and central Plains states. There has been
an increase in T- races with virulence to Lr9 and Lr10
in the southern SRWW area. There also has been an increase in
the number of T- races (TNRS, TNRJ, TNGS and TNGJ) with virulence
to Lr9, Lr10, and Lr24 in Texas. Many of
the T-races with virulence to Lr9 and Lr24 were
identified from collections made from the cultivars Lockett (Lr9
resistance) and Thunderbolt (Lr41 resistance). Race MBBJ
was the predominant race found in California as it has been for
the past 10 years.
Table 2. Wheat leaf rust code and corresponding
virulence formula for collections made in 2002.
Yield loss estimates due to leaf rust are in Table 4 (winter wheats) and Table 5 (spring and durum wheats).
Wheat stripe rust. Great Plains. In mid-January 2002,
hot spots (70-80 % severities) of stripe rust infection were found
in central Texas wheat plots. This indicated that stripe rust
may have overwintered in this region. In early February, stripe
rust was light in plots in southern Texas. In early March, stripe
rust was slowed by cold temperatures in southern Texas plots,
but was at 50-70 % severity on lower leaves. The cold temperatures
in early March damaged leaves and destroyed much of the rust infected
leaf tissue. In the third week in March, rain improved conditions
for rust development in much of central and southern Texas. Stripe
rust requires cool temperatures (generally less than 70°F)
and moist conditions for infection and development. In 2002, stripe
rust was widespread and survived the cold temperatures in early
March in greater amounts than leaf rust.
In early April, light stripe rust was found in wheat fields
in southern and central Texas and from trace amounts to approximately
40 % severity in southern Texas nurseries. Stripe rust severities
on SRWW cultivars generally were higher than those on the HRWW
cultivars in the southern and central Texas nurseries. Jagger
and Cutter were two cultivars that had the best stripe rust resistance
in the Uvalde nursery in southern Texas.
By mid-April, wheat stripe rust development in central Texas
had slowed in some areas, but was still active despite the warm
weather in southcentral Texas. From initial collections made in
central Texas race PST-79 was identified. This race was very prevalent
in Texas and Great Plains in 2001. By late April, the warmer temperatures
slowed stripe rust development in central Texas and eastern Oklahoma.
In the first week in May, wheat stripe rust was still active
on some cultivars in northern Texas plots. In early May, severe
wheat stripe rust was reported in north central Oklahoma plots;
in fields in the same area rust was light or not found. In early
May, stripe rust was observed in southcentral Kansas. In mid-May,
a 2-meter foci of stripe rust was found in a plot of the highly
susceptible cultivar Lakin in northeastern Kansas. In late May,
traces of stripe rust were found in central and southern Kansas
plots and fields (Figure
2). In late May, traces of stripe rust were found in wheat
plots in eastcentral Nebraska.
Much less stripe rust was found in Oklahoma and Kansas in 2002
than in 2001. In both years, cool spring and night temperatures
in the 40s and 50s, plus humid weather were conducive for stripe
rust development throughout the Great Plains.
Louisiana, Arkansas and Missouri. In mid-March, stripe
rust was severe in plots in a southern Louisiana. In mid-April,
northeastern Louisiana fields had stripe rust infections of 40
% severity. Across all of Louisiana, stripe rust was at moderate
levels, and a number of fields were sprayed with fungicides to
reduce yield losses. Significant amounts of stripe rust have occurred
in three of the last 5 years in Louisiana. Wheat lines Coker 9663
and AGS 2000 were resistant to stripe rust in Louisiana.
By the third week in February, foci of rust infection were
in northwestern Arkansas fields and in plots in southwestern Arkansas.
In late March, stripe rust was found in fields and cultivar demonstration
plots in eastcentral Arkansas. In mid-April, warm weather slowed
the development of stripe rust in Arkansas. In the first week
in May, stripe rust development had slowed in southern Arkansas
but in the northern part of the state, rust infections were still
In 2002, stripe rust developed in the lower Mississippi Valley
area. Stripe rust caused significant yield losses in Arkansas
in 2002 (Table 4).
Infection levels of up to 95 % severity at flowering stage were
seen in fields and research plots. The fungicide Tilt was widely
used to reduce stripe rust infections and yield losses. Stripe
rust was not as severe in Arkansas as in 2000, because the cultivar
CK 9663 (which comprises half of the acreage) was more resistant
In the third week in May, soft red cultivars at the late-berry
stage in westcentral Missouri had 40 % stripe rust severities.
Weather conditions were conducive for the stripe rust inoculum
coming from infection sites in Louisiana leading to increased
stripe rust in Arkansas and Missouri. In 2002 more stripe rust
overwintering sites occurred further east in the U.S. These focal
points of stripe rust originated from infections that were established
in the autumn of 2001. A general relationship exists between rust
severity and the amount of rust that has overwintered.
Southeast. In mid-April, light amounts of stripe rust
were found in southern Alabama wheat plots. In early May, stripe
rust was found in plots in northcentral Alabama. Severities ranged
from traces to 40 %.
Virginia and Maryland. In mid-May, traces of stripe
rust were found scattered throughout the state of Virginia. In
late May, wheat stripe rust was higher than normal in the plots
at the Blacksburg, Virginia. In mid-June, stripe rust was found
in eastcentral Maryland plots.
Ohio Valley. During the third week in May, stripe rust
foci were found in plots in southwest Indiana. The wheat was in
the early milk stage. In mid-June, fields of SRWW cultivars in
northeastern Missouri to northwestern Ohio had trace to 10 % stripe
rust severities (Figure
2). In mid-June, traces of stripe rust were found in winter
wheat plots in southcentral Wisconsin.
California. By late April, moderate to severe wheat
stripe rust was reported on susceptible cultivars in the Sacramento/San
Joaquin Valley Delta and the Sacramento Valley. In mid-May, stripe
rust of wheat had spread throughout the Central Valley of California.
In the San Joaquin Valley, some durum wheat cultivars also had
stripe rust infections, but at lower levels than hard red wheat.
In 2002, stripe rust development in California was less than normal
because of the drought-like conditions in late winter.
Pacific Northwest. The 2002 wheat stripe rust epidemic
was the most severe in the last 5 years in the PNW. Stripe rust
severity of 100 % occurred on susceptible entries in wheat nurseries
in western Oregon, western Washington, eastern Washington, and
northern Idaho. Although some susceptible winter wheat cultivars
had severe rust, the stripe rust epidemic mainly affected spring
wheat crops in eastern Washington and northern Idaho. The recently
released cultivar Zak, which was grown on over 93,000 acres in
Washington and ranked the No. 2 spring wheat cultivar in 2002,
was susceptible. Most of the susceptible spring wheat fields were
sprayed with fungicides. Stripe rust caused multimillion-dollar
losses including fungicide cost and application (Table 5).
Race PST-78 (virulent on Lemhi, Heines VII, Lee, Fielder, Express,
Yr8, Yr9, Clement, and Compair) and similar races, which were
predominant in California, southcentral states, and the Great
Plains in 2000, 2001, and/or 2002, became prevalent in the PNW
in 2002. The relatively warm winter and cool weather in spring
and summer were favorable to survival and development of the rust.
The relatively large acreage of susceptible cultivars like Zak
made the severe and large-scale epidemics possible. Fortunately,
the No. 1 spring wheat cultivar Alpowa (about 280,000 acres in
Washington) and most of winter wheat cultivars (over 70 % of total
wheat acreage in Washington) still showed good high-temperature,