A Database for Triticeae and Avena
UNIVERSITY OF MINNESOTA AND USDA-ARS PLANT SCIENCE RESEARCH UNIT
Department of Agronomy and Plant Genetics, University of
Minnesota and USDAARS, St. Paul, MN 55108, USA.
J. Anderson, R. Busch, G. Linkert, L. Matthiesen, E. Wennerlind,
A. Procopiuk, H. Mickelson, S. Liu, K. McGowan, J. Gonzalez, D.
Bowen, G. Hareland, M. Pumphrey, R. Dill-Macky, C. Evans,
W. Thompson, J. Wiersma, K. McGowan, and D. Bowen.
Dr. Robert Busch retired June, 2000. J. Gonzalez joined our
project as a postdoctoral research associate in April. D. Bowen
and M. Pumphrey are new M.S. students. Dr. Ana Maria Procopiuk
accepted a position as a postdoctoral research associate at the
University of Illinois.
Minnesota produced an estimated 79.2 million bushels (2.67
million metric tons) from 1.99 million acres (0.81 million hectares)
in 1999. Losses from leaf rust were estimated at 4 %. During the
1998-99 crossing cycle, 317 crosses were made. Most of these crosses
involved elite germ plasm from the University of Minnesota HRSW
breeding program and sources of FHB resistance. A total of 1,980
lines were under small-scale increase (8 ft. rows) in the 1998-99
winter nursery in California. A total of 17,000 F3 seeds were
planted in New Zealand in the autumn of 1998 for generation advance
by SSD. During the 1999 growing season, 439 and 140 experimental
lines were evaluated in replicated preliminary and advanced yield
trials, respectively. The preliminary yield and advanced yield
trials were grown at two and three locations, respectively. The
Variety Trial, which contained 31 released varieties and two University
of Minnesota experimental lines, was grown at seven locations.
FHB-inoculated, misted, replicated nurseries were established
at three locations. Approximately 2,500 lines were tested for
FHB resistance in the greenhouse during the past year. Most of
these materials were experimental lines, but also included potential
new resistance sources from China and elsewhere and materials
for genetic studies. McVey (MN93413) was released in 1999. Developed
under the project leadership of Dr. Robert Busch, McVey has shown
high yield levels, even in the presence of FHB.
J.A. Anderson, S. Liu, and E. Wennerlind.
We continued research to identify and map DNA markers linked
to genes controlling FHB resistance in two spring wheat RILs.
Both populations are segregating for genes from the widely used
resistance source Sumai 3. The first population is from the cross
'Sumai 3/Stoa', in which we previously identified five resistance
QTLs. The second population is from the cross 'ND2603 (Sumai 3/Wheaton)
(resistant)/ Butte 86 (moderately susceptible)'. Both populations
were evaluated for reaction to inoculation with F. graminearum
in two greenhouse experiments by R. Stack, North Dakota State
University. A combination of 521 RFLP, AFLP, and SSR markers were
mapped in the 'Sumai 3/Stoa' population and all DNA markers associated
with resistance were screened on the 'ND2603/Butte 86' population.
Two new QTL on chromosomes 3AL and 6AS were found in the 'ND2603/Butte
86' population, and AFLP and SSR markers were identified that
explained a greater portion of the phenotypic variation compared
to the previous RFLP markers. Both of the Sumai 3-derived QTL
regions (on chromosomes 3BS, and 6BS) from the 'Sumai 3/Stoa'
population were associated with FHB resistance in the 'ND2603/Butte
86' population. Markers in the 3BS QTL region (Qfhs.ndsu-3BS)
alone explain 41.6 and 24.8 % of the resistance to FHB in the
'Sumai 3/Stoa' and 'ND2603/Butte 86' populations, respectively.
This region contains a major QTL for resistance to FHB and should
be useful in marker-assisted selection.
M.O. Pumphrey, J. Gonzalez, E. Wennerlind, and J. Anderson.
Eight hundred seventy lines from our 2000 F4 headrow nursery
were screened with SSRs for the presence of the 3BS FHB QTL (Qfhs.ndsu-3BS).
Three hundred and 157 were homozygous and heterozygous, respectively,
for the QTL. Four hundred thirteen lines did not contain the QTL
and were discarded based on our marker analysis. The resistance
level associated with the Qfhs.ndsu-3BS QTL is expected to be
observed in a high proportion of the 457 lines containing this
QTL. Using a LiCor DNA analyzer, we estimate our costs for this
marker screening at approximately $0.90 for the first SSR run
on a genotype, including all consumables and labor. This is reduced
to about $0.50 per data point for additional SSRs on the same
genotype. We are experimenting with various DNA extraction protocols
with the goal that one person can prepare PCR-ready DNA from leaf
tissue from at least 400 lines in one day.
We plan to test the effectiveness of this FHB screening procedure
by examining the FHB reaction of near-isogenic lines with and
without the QTL in a wide variety of genetic backgrounds. Approximately
50 F4 and/or F5 derived lines, near-isogenic for the chromosome
3BS QTL, have been isolated from the heterozgous F4 lines identified
from the 2000 F4-headrow nursery. These lines (50 homozygous with
the QTL and 50 sib-lines without the QTL) plus checks will be
evaluated under greenhouse conditions and in field FHB nurseries.
We also are backcrossing this QTL into advanced lines.
A. Procopiuk, G. Hareland, and J. Anderson.
The introgression of genes for FHB resistance from Chinese
resistance sources has also resulted in the incorporation of HMW-glutenin
subunits that are not favorable for the production of yeast-leavened
products. We surveyed all Minnesota experimental HRSWs that were
entered in our 2000 advanced yield trials to assess the degree
of introgression of the unfavorable alleles (Table 1). Based on
the literature, we expect that the null allele (n) at the Glu-A1
locus and the 2+12 allele at the Glu-D1 locus would be particularly
detrimental for yeast-leavened products. Our preliminary analysis
of this data confirms those findings, though there were several
interesting cases in which lines with undesirable HMW-glutenin
patterns produced strong mixing doughs with high loaf volume.
We are using this information to guide parental selection for
Table 1. High molecular weight-glutenin
patterns of 133 Minnesota experimental hard red spring lines entered
in 2000 advanced yield trials. HMW-glutenin pattern includes alleles
at Glu-A1, Glu-B1, and Glu-D1.
H. Mickelson, R. Busch, R. Dill-Macky, C. Evans,
W. Thompson, J. Wiersma, and J.A. Anderson.
Our objective was to predict optimum resource allocation for
line discard during early-generation evaluations, and for accurately
determining Fusarium head blight (FHB) reaction during advanced-generation
line evaluations. Replicates of 14 cultivars were evaluated in
10 inoculated Minnesota FHB screening nurseries from 1997-2000.
FHB reaction was determined on spikes in the field (disease index),
and on harvested grain as percent visually scabby kernels (VSK)
and deoxynivalenol (DON) concentration. Consistent and strong
correlation was observed between VSK and DON across all environments,
even though several fold differences in trait expression were
observed. The pooled r-value was 0.87 (n = 14). Disease
index, VSK, and DON concentration likely represent different aspects
of FHB resistance, and did not always rank the cultivars the same.
McVey ranked second for disease index, sixth for VSK, and eleventh
for DON, suggesting that each trait needs to be evaluated. Based
on predicted LSD0.05, evaluations of disease index on 20 spikes
plot-1, with two replicated row plots in three environments, along
with determination of percent VSK, appears ample for early-generation
evaluations. Although less advisable, a single environment could
be used. Stability analysis was used to determine the number of
environments needed to identify 'stable' FHB resistance in advanced
lines. Disease index and VSK should be evaluated in 5 to 7
environments to thoroughly characterize FHB reaction, and DON
evaluated in 3 to 5 environments.
K. McGowan, D. Bowen, and J. Anderson.
We are examining the inheritance of FHB resistance and trying
to find DNA markers from two additional sources, Wuhan 3 and Fujian
5114. Wuhan 3 is a Chinese Spring wheat from an early generation
population collected by CIMMYT personnel at a Chinese Experiment
Station near the city of Wuhan in the province of Hubei. The pedigree
is unknown. Fujian 5114 is from the Fujian province of China where
FHB epidemics occur on an annual basis. The pedigree is 'Longxi18/Ning8017'.
RIL populations from each resistance source crossed with the susceptible
cultivar Norm have been evaluated in the field and greenhouse
for FHB reaction. Preliminary data with these populations and
crosses between the two resistance sources and Sumai 3 indicates
that they possess novel resistance genes.
Our goal for each of these populations is to explain at least
60 % of the phenotypic variation in FHB resistance. At this level,
we can be confident that all major (and breeding relevant) QTL
were discovered. We will continue to build a skeleton map covering
all chromosomes at approximately 20 cM density until the goal
CEREAL DISEASE LABORATORY - USDA-ARS
University of Minnesota, 1551 Lindig, St. Paul, MN 55108,
D.L. Long, K.J. Leonard, D.V. McVey, J.A. Kolmer, M.E. Hughes,
and L.A. Wanschura.
Stem rust. In 2000, except for light infections in Texas, there
were few reports of stem rust in wheat fields in the southern
U.S. The first wheat stem rust report was in mid-March, when traces
were found in plots of soft red winter wheats at the Uvalde experiment
station in southern Texas.
By mid-April, wheat stem rust was severe in south Texas plots
and light in central Texas plots and 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 on susceptible
entries throughout the plots. By the end of April, traces of wheat
stem rust were observed in southern Louisiana plots.
In mid-May, traces of wheat stem rust were found on the cultivar
2137 at the south-central Kansas experiment station at Hutchinson.
During late May, foci of 20 % severity were observed scattered
throughout a SRWW field in west central Missouri and traces were
found in a south central Kansas HRWW 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,
westcentral Indiana, and southcentral Wisconsin. Rust severities
ranged from 1 to 20 % in the center of the foci to trace level
(< 1 %) at about 1 foot from the center. In eastern Nebraska,
leaves of HRWW were heavily infected, but stems were only slightly
infected. On 18 June, traces of stem rust were found on the HRWW
cultivar 2137 in southeastern North Dakota. Rust pustules were
found on both the leaf blades and leaf sheaths, which is unusual
for stem rust except when the spores are rain deposited, as most
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 eastcentral
South Dakota and eastcentral 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 southcentral Minnesota and eastern South Dakota
plots. In the southcentral Minnesota plots on 22 June, only traces
were observed on Baart wheat. The rust development was due to
spores that 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 eastcentral 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 eastcentral
North Dakota nursery. During the fourth week in July, trace-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
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.
Stem rust races. The preliminary results from the 2000
national stem rust survey indicate the most commonly identified
races in 2000 are QCMS, QCMJ, RCMS, RCRS, QCCS, QCCJ, and QFCS.
Further testing is underway and the final results will be published
in Plant Disease. From 1993 to 1997, race Pgt-TPMK was the most
common wheat stem rust found in the U.S. and in 1999 it had dropped
to the third most common. In 2000, TPMK was not identified from
samples received at the Cereal Disease Laboratory. The QCCJ race
is virulent on barley cultivars with the Rpg1 (T) resistance
gene. Race RCRS was the most commonly identified race in 1998
and 1999. In 1999, races QCCS and QCMS were only found in North
Dakota and in 2000 were identified from Texas rust collections.
Wheat leaf rust. Southern Plains. In early February,
light amounts of leaf rust were found on the susceptible cultivar
TAM 107 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
northcentral Texas and southern Oklahoma plots ranged from trace
to 80 %. Severities were as high as 70 % in fields where rust
overwintered (Fig. 1).
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 southcentral
Kansas in early April. During the third week in April, in southcentral
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 was similar to leaf rust development
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 northcentral Kansas
because of the dry conditions which prevented rust infections
during early May.
During the last week in May, trace-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 westcentral Missouri,
20 % severities were observed on susceptible cultivars at the
early berry stage. In late May, in southcentral Kansas spring
wheat plots (i.e., 2375), trace20 % severities were observed
at the one-forth 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 % (Table 5), which is below
the 10-year average of 4.8 %, but close to last year's estimate
of 3.5 %. Yield losses were estimated from fungicide plot data,
cultivar surveys, cultivar disease ratings and disease surveys.
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 eastcentral 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
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-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
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 southcentral Minnesota plots. In fields,
severities ranged from trace to 10 % on the lower leaves of spring
wheats in western Minnesota and eastern South Dakota.
In late July, trace-10 % severities were found in spring wheat
fields and trace-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, leaf rust severities were normal but less than last
year. Some losses occurred in the northern spring wheat growing
area, especially in late planted fields and in fields that were
This year, 1-2 % leaf rust losses were reported in the northern
plains states (Table 4).
This 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
Canada. By late July, in fields not sprayed with fungicides,
trace-5 % severity was found on wheat in southeastern Manitoba.
Leaf rust infections in the southcentral area were lighter with
only trace amounts of leaf rust. Some late planted wheat fields
seeded with susceptible varieties experienced 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, whereas 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 SRWWs in the southeast
had 80 % leaf rust severities by early May, but fields generally
had trace-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
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
In 2000, in North Carolina, 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
In fields, infection levels were generally light to moderate,
because of 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 also is 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, Lr16, Lr17, Lr19,
Lr21, Lr23, Lr24, Lr25, Lr26,
Lr29, Lr33, Lr41, Lr42, and Lr43
at Kinston, NC showed useful resistance to leaf rust.
By late May, 5-80 % 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
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 SRWW 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
Pacific Northwest. In early July, wheat leaf rust was
increasing on spring wheats in eastern Washington fields and susceptible
wheats in nurseries had 6070 % severities.
Wheat leaf rust virulence. The 2000 leaf rust race identifications
from collections made in the U.S. are presented in Tables 1 and
2. From the central and southern Plains rust collections the most
common races were M-races (virulent to Lr1, Lr3,
Lr10, Lr17, and Lr+). Many of the MBDS and
MCDS 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, Lr2a, Lr2c, Lr3,
and Lr+), particularly, an increase in T races with virulence
to Lr9 and Lr10 in the southern SRWW area. This
Lr9 and Lr10 combination has rarely been found in
past leaf rust surveys.
Wheat stripe rust. Southeast. This year, wheat stripe
rust was reported in a southern Georgia nursery for the first
time since 1974. On 9 May, a wheat stripe rust focus 1 m in diameter,
was found in northwest Georgia (Fig.
2). This is one of the first records of stripe rust ever being
found in north Georgia. In late April, stripe rust was light in
northern Alabama plots. In westcentral Mississippi plots where
it was dry, wheat stripe rust was more scattered and easier to
evaluate than wheat leaf rust. Trace losses were reported throughout
the southeastern U.S.
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. By the third
week in April, wheat stripe rust was severe in commercial fields
throughout northwestern Louisiana. The wheat stripe rust loss
in Louisiana was estimated to be 0.5 % (Table 4).
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. 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 of the fungicide Tilt was sprayed this year in Arkansas than
in any of the last 5 years. As of early May, stripe rust was still
increasing in northern Arkansas because there still had not been
any prolonged periods of hot weather, which usually stops stripe
rust development. 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. Estimated
losses to stripe rust in Arkansas reached 7.0 % (Table 4), which was the largest loss reported
in recent history.
Southern Plains. During late March, infections of stripe
rust that had overwintered were found on the lower leaves of SRWW
cultivars at the Uvalde, Texas experiment station. By the third
week in April, wheat stripe rust was severe in commercial fields
throughout northeastern Texas. 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, SRWW 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. There was an estimated
10 % loss to wheat stripe rust in northeastern Texas and overall
a 0.5 % estimated loss in the state.
By late April, wheat stripe rust was severe in southern Oklahoma.
This year estimated losses to stripe rust totaled 1.0 % (Table 4) of the yield in the state.
Central Plains. In mid-May, stripe rust was found throughout
Kansas. The mild winter and cool spring were conducive for stripe
rust development. In southcentral Kansas plots, stripe rust was
severe on a few of the HRWW cultivars, especially those with the
T1B·1R gene translocation, which indicated virulence to
Yr9. In late May, stripe rust was observed throughout eastern
Kansas, northwestern Missouri and southeastern Nebraska fields.
In southcentral Kansas plots, severities ranged from traces to
60 %, whereas in Nebraska fields, 1 % severities were observed.
This year in the Great Plains, the cool spring and night time
temperatures 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. Losses to wheat
stripe rust in Kansas were estimated to be 0.05 % (Table 4).
Northern Plains. 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. On 8 June,
light amounts of wheat stripe rust were found in SRWW plots at
Rosemount, MN. 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.
In late June, wheat stripe rust was widespread in central and
eastern South Dakota on winter wheat. In plots at Brookings, some
winter wheat entries had a high level of infection, e.g., 80 %
on Siouxland, which has the T1B·1R gene translocation and
indicates virulence to Yr9. Traces of stripe rust were
found easily in spring wheat fields and nursery plots. In rust
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
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.
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.
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 SRWW
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.
Northeast. In mid-May, traces of stripe rust were found
in plots in Blacksburg, VA, 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 2 years
ago light amounts of wheat stripe rust were scattered from the
lower Mississippi Valley north to eastcentral 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 was cooler than normal, favoring
stripe rust development. A large source of inoculum appears to
have arrived early in the crop growing year in the southern U.S.
from some location like 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. Estimated losses
to stripe rust were 3.0 % in California this year (Table 4).
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.
By 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 1.0 % or less,
since most of the cultivars have high temperature, adult plant
resistance (Table 4).
Canada. In late July, trace-l5 % stripe rust severities
were reported in spring wheat fields in southeastern and south
central areas of Manitoba. Because of 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.
3. Races of Puccinia recondita f. sp. tritici identified
from wheat collections in 2000.
4. Estimated losses in winter wheat due to rust in 2000.
5. Estimated losses in spring and durum wheat due to rust in 2000.