CEREAL RUST BULLETIN
Final Report
August 8, 1995
Issued by:
Cereal Rust Laboratory, Agricultural Research Service, USDA
University of Minnesota, St. Paul, MN 55108
(612) 625-6299 FAX (612) 649-5054
Internet: markh@puccini.crl.umn.edu
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* Wheat stem rust caused little damage to wheat in 1995, but stem rust
on barley in the northern Great Plains was more severe in 1995 than in
any year since 1991.
* Wheat leaf rust was widespread in winter wheat throughout the southern
U.S. and caused an estimated loss of 5% in Kansas.
* Wheat stripe rust in the Pacific Northwest was effectively controlled
by adult plant resistance in most varieties, although susceptible
varieties were heavily infected.
* Oat stem rust in 1995 was largely confined to the southern states,
where it caused some damage in Texas and Louisiana.
* Oat crown rust was severe throughout much of the southern U.S. and
Upper Midwest in 1995; North Carolina, Pennsylvania, Ohio, and
Saskatchewan reported unusually high levels of crown rust at locations
where it was rarely seen in previous years.
* Barley leaf rust was found throughout the northern barley-growing area
but severities were too low to affect yields.
* Barley stripe rust became firmly established throughout the Pacific
Northwest.
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Most of the small grains in the northern Great Plains are in good
condition and near normal in maturity. Scab is severe in many western
Minnesota and eastern North Dakota spring wheat fields. Losses will
occur mainly in fields with rainfall at the anthesis growth stage.
Barley and winter wheat harvests have begun in northeastern North Dakota
and northeastern Montana.
Wheat stem rust
This year, wheat stem rust was found scattered in plots and fields
throughout the southern Plains and the lower Mississippi Valley wheat-
growing area. In all of these areas losses to wheat stem rust were
minimal, but these fields and plots did provide stem rust inoculum for
susceptible wheats and barleys farther north.
During 1995, wheat stem rust overwintering sites were found in southern
Texas, Louisiana, southwestern Georgia, northeastern Arkansas and
southwestern South Carolina. During the last week in March, traces of
stem rust were found in winter wheat fields southwest of Houston,
southeast of San Antonio and in a nursery at Beeville, Texas. Stem rust
development in southern Texas and Louisiana was normal in 1995 but less
than in 1993, the last year with significant wheat stem rust in the U.S.
The year 1993 and other recent years with greater than average stem rust
generally had warmer late winters and early spring weather with more
rainfall than occurred in 1995. In mid-April, widespread stem rust (5%
severities) was found in commercial fields of CK 9835 and Savannah in
central Louisiana, and these fields were sprayed with Bayleton to stop
further stem rust development. By late April, traces of stem rust were
found in winter wheat plots from central Texas to southwestern South
Carolina. In early May, wheat stem rust was severe on susceptible
cultivars in southern and central Texas nurseries. During the second
week in May, stem rust severities were light around the overwintering
site in a field of CK9835 in northeast Arkansas. In mid-May, stem rust
was light on susceptible cultivars growing in plots in northeastern
South Carolina. The wheat stem rust that infected plots in a
southwestern South Carolina nursery probably overwintered in a field of
volunteer CK9835 growing in close proximity to the plots. During the
third week in May, severe stem rust was found in a plot of Saluda in
northwestern Arkansas and in a plot of Chisholm in southwestern
Oklahoma. In late May, wheat stem rust was found in a wheat plot in
southwest Missouri. During the second week in June, wheat stem rust
foci were observed in fields of soft red winter wheat in southern
Illinois and in wheat plots in southwestern Indiana at the soft dough
stage. In the center of the foci, 40% severities were common; however,
eight feet from the center only traces of rust were present. Stem rust
spores apparently were deposited 4-6 weeks earlier, but expansion of the
foci from sites of initial infections was restricted by frequent rains
that kept the wheat canopy wet and prevented newly produced spores from
being released and carried out of the canopy by wind currents. In mid-
June, traces of wheat stem rust were reported in a west central Indiana
nursery. Losses were negligible in the northern soft red winter wheat
area.
During late June, 10% stem rust severities were found in northeastern
and northwestern Kansas plots of McNair 701 at the hard dough stage.
The hot dry weather in Kansas in late May and early June was not
conducive to rust increase.
On June 19th, traces of wheat stem rust were found on the susceptible
spring wheat cultivar Baart in southern Minnesota plots. In early July,
traces of stem rust were found in a hard red winter wheat plot in
southeastern North Dakota. In mid-July, traces of wheat stem rust were
found in plots of the susceptible spring wheat Baart in east central
South Dakota, southeastern North Dakota and west central Minnesota.
Several factors delayed stem rust development in the central Great
Plains. First, stem rust overwintering north of Texas was less than
normal. Then; cool dry conditions in late winter in the southern Plains
and hot dry weather in late May and early June in the central Plains
were not conducive to rust increase. In spite of this, sufficient
quantities of stem rust spores spread from the central Great Plains to
initiate stem rust foci in susceptible spring wheat plots in the
northern Great Plains. Stem rust from these foci developed normally.
Commercial spring wheats were not damaged because their stem rust
resistance is still highly effective.
In mid-July, traces of wheat stem rust were detected in wheat plots in
eastern Washington but none was reported in fields.
To date, race Pgt-TPMK is the predominant stem rust race identified in
1995 as it was in 1994. Race Pgt-RCRS was not found in Texas in 1994,
but this year it comprises almost 41% of the isolates identified from
Texas (Table 1). Race Pgt-QCCJ (which infects barley with the T gene
for resistance) was identified from stem rust collections made in wheat
nurseries in central Texas and northwestern Arkansas.
TABLE 1. Wheat stem rust races identified through August 8, 1995
___________________________________________________________________________
Number of Number of isolates of Pgt race*
______________________ ___________________________________________
State collections isolates QCCJ QCCS QFCS RCMS RCRS TPMK
___________________________________________________________________________
AR 3 9 3 6
IL 3 9 9
IN 3 9 9
KS 1 3 3
LA 4 11 11
MN 3 9 8 3
NC 1 3 3
NE 2 6 6
OK 1 1 1
SC 1 3 3
TX 13 32 3 3 3 13 10
VA 2 6 6
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* Virulence formula:
QCCJ - Sr5,21,9g,17,9d,10 RCMS - Sr5,21,7b,9g,36,17,9a,9d,10
QCCS - Sr5,21,9g,17,9a,9d,10 RCRS - Sr5 ,21,7b,9g,36,9b,17,9a,9d,10
QFCS - Sr5,21,8a,9g,17,9a,9d,10 TPMK - Sr5,21,9e,7b,11,8a,9g,36,17,9d,10,Tmp
Wheat leaf rust
During the last week in March, leaf rust was widespread in winter and
spring wheat fields throughout southern and central Texas. Rust
severities on lower leaves ranged from 0 to 20% in fields and from 0 to
60% in nurseries, which was normal for this date (Fig. 1). Generally,
leaf rust overwinters throughout southern Texas. In northern Texas
fields and nurseries in late March, leaf rust was more severe than 1994.
Lack of moisture in northern Texas delayed further leaf rust
development, but by mid-April the rains had returned. In late April,
leaf rust severities in southwestern Oklahoma wheat fields and plots
ranged from traces to 20%. These represent normal rust severity
readings for this area for late April. By mid-May, leaf rust severities
in north-central Oklahoma wheat fields and plots ranged from traces to
40%.
In contrast to the 1993-94 winter, when little leaf rust overwintered in
Kansas, normal amounts of rust overwintered in eastern and central
Kansas in 1994-95, while overwintering was greater than normal in
western Kansas. In some fields, scattered volunteer plants were found
with significantly higher incidences of rust than the majority of the
field. Because volunteer winter wheat plants normally emerge before the
crop is planted, they tend to be more heavily rusted in the fall.
Usually, the infections on volunteer plants do not survive the winter in
Kansas. In mid-April, leaf rust was generally light in Kansas (Fig. 1),
although a few locations were observed with heavier infections.
Freezing temperatures in early April killed some infected leaf tissue in
western Kansas, which delayed local rust buildup. In late April, a hard
freeze in western Kansas and northwestern Oklahoma killed much of the
leaf tissue where rust had developed. By the second week in May, leaf
rust was increasing at a very slow rate throughout Kansas because the
cool moist weather was not conducive to rust increase. The moist
conditions kept the wheat canopy wet and created conditions whereby the
spores remained within the canopy. Leaf rust was severe on the lower
leaves of susceptible cultivars, e.g., Karl 92, but rust development on
the flag leaves was light. During early June in central Kansas, rust
severities ranged from greater than 60% to less than 10% in some fields
a short distance apart. Losses varied with local conditions but some
fields suffered significant losses in yield. In mid-June, hot dry
weather in northern Kansas and southern Nebraska prematurely dried many
wheat leaves, thereby slowing leaf rust development. In mid-June, in a
wheat field in Rooks Co., Kansas, 80% severities were observed on
goatgrass(Aegilops cylindrica) plants. The leaf rust loss estimate in
Kansas in 1995 is 5%, which is significantly more than the 1% loss in
1994, but half the loss of 1993. During the third week in June 40-60%,
severities were found on susceptible wheat cultivars in east-central
Nebraska plots. In late June, in south-central Nebraska fields, the hot
dry weather prematurely dried many leaves on wheat plants, but on the
few remaining green flag leaves, 40% leaf rust severities were common.
In this area, losses will vary with local conditions, but some fields
suffered losses in yield of greater than 5%.
On April 28, the first pustules of leaf rust were observed in the
northern Great Plains on green winter wheat leaves just breaking winter
dormancy at the Rosemount, Minnesota nursery in east central Minnesota.
Leaf rust was found on the winter wheat cultivar Roughrider in
southeastern North Dakota fields on June 2, and on June 15 the incidence
and severity (traces) were relatively unchanged. During the third week
in June, in southern Minnesota plots, the susceptible cultivar Baart had
10% leaf rust severities on the lower leaves. During early July, 20-60%
severities were observed in southeastern North Dakota winter wheat plots
and fields at soft dough stage. Only traces were observed on lower
leaves in spring wheat plots and fields at early milk growth stage. In
mid-July, severities of trace-60% were common on flag leaves in east
central Minnesota and eastern South Dakota winter wheat plots. In
susceptible spring wheat plots, trace-20% severities were common. Due
to resistance, only traces of leaf rust developed in commercial fields
and therefore losses were minimal in spring wheats. No rust was
reported on durum wheat.
In mid-June, leaf rust was detected on flag leaves of winter wheat in
plots south of Winnipeg, Canada. The infections were heavier than
normal for mid-June.
In the southeast U.S., during late March leaf rust severities were
generally light to moderate on susceptible southern soft red winter
wheat in plots and fields (Fig. 1). The winter rainfall in these areas
was above normal, creating favorable conditions for rust infection.
Cool temperatures in January and February slowed rust development, but
warm temperatures and moist conditions in March were favorable for rust
buildup. By late April, light amounts of leaf rust were found on
susceptible cultivars in nurseries and fields in eastern North Carolina.
By early May, leaf rust severities were generally light to moderate on
susceptible southern soft red winter wheat in plots and fields from
northern Mississippi to southern South Carolina (Fig. 1). By the second
week in May, leaf rust severities ranged from traces to 80% in wheat
plots and fields at the soft dough stage in southeastern North Carolina.
These rust-infected plants provided leaf rust inoculum for wheats
farther north. In mid-June, the hot dry weather dried the leaves
prematurely and thereby restricted rust development. This year
throughout the southern soft red winter wheat there was an increase of
rust on Northrup King/Coker 9835 which is grown on significant acreage.
This signified an increase in races with virulence to Lr9 in this area
since Coker 9835 has Lr 9 as part of its leaf rust resistance (Table 2).
In mid-June, trace to 40% leaf rust severities were observed in southern
Illinois and southwestern Indiana soft red winter wheat fields and
nurseries at the soft dough stage (Fig. 1). Farther north in the
northern soft red winter wheat areas in northwestern Ohio, only traces
of wheat leaf rust were found in fields and plots at the half-berry
stage. In central Michigan, however, leaf rust was moderately severe by
the second week in June, suggesting that leaf rust overwintered there.
In mid-June, leaf rust was present in light amounts in winter wheat
fields in eastern Wisconsin. During mid-June, traces of leaf rust were
found in the lower canopy of winter wheat near Aurora in the Finger
Lakes area of New York at the watery-ripe growth stage, suggesting that
leaf rust may have overwintered there.
During the last week in June, the aecial stage of leaf rust was found on
meadow rue (Thalictrum fendleri) growing in the Rio Grande National
Forest in south-central Colorado. The form of leaf rust found has not
been determined, but it is most likely a form that attacks some wild
grasses, but not wheat.
In late April, leaf rust was light in plots and fields in the Sacramento
Valley of California. By the first week in May, in the San Joaquin
Valley of California, wheat leaf rust was widespread and severe on
susceptible cultivars in fields and nurseries. During the first week in
May, leaf rust was light in eastern Oregon and eastern Washington
fields. By the third week In June, leaf rust severities as high as 80%
were found in irrigated winter wheat at early dough stage in central
Washington and severities were light to moderate in dry land wheat in
central Washington and trace to light in the Palouse area of eastern
Washington. In mid-July, in the Palouse area of Washington, 80%
severities were observed on susceptible winter wheat cultivars growing
in nurseries while in fields rust was less.
From collections made in south Texas in late March, leaf rust races MCD-
10 virulent to Lr1,3,10,17,26; MBJ-10 virulent to Lr1,3,10,11,17; MBR-10
virulent to Lr1,3,3ka,10,11,30; MCR-10 virulent to
Lr1,3,3ka,10,11,26,30; TFB-10 virulent to Lr1,2a,2c,3,10,24,26; TDG-10
virulent to Lr1,2a,2c,3,10,11,24; TLG-18 virulent to Lr1,2a,2c,3,9,11,18
and PNM-10,18 virulent to Lr1,2c,3, 3ka,9,10, 24,30 were identified
(Table 2). The MCD-10 race was identified from a collection made from
the cultivar Jagger. Last year race MBR-10 comprised 36% of the U.S.
race population.
The wheat leaf rust races identified so far in the 1995 survey are
presented in Table 2. There has been a increase in the number of races
with Lr 26 as part of their virulence package. In 1994, five different
races with Lr 26 virulence had been identified by mid-July, while eleven
races with Lr 26 virulence have been identified in 1995. Race SBD
(virulent on Lr 1,2a,2c,17) was identified from two Triticum (Aegilops)
cylindrica collections made in southwestern Oklahoma. This is the same
race identified from T. cylindrica collections in previous surveys.
The interesting thing about this race is that it is avirulent on Lr 3
and 10 but it has not been identified from collections made from wheat
in southwestern Oklahoma and northern Texas.
TABLE 2. Wheat leaf rust races identified through August 8, 1995
__________________________________________________________________
Race* Number of isolates by state
_______________________________________________________
AL AR CA CO FL GA IN KS LA NC OK SC TX VA
__________________________________________________________________
CBG-10,18 2
FBT-18 1
FCD-10 2
LBB-10,18 3
LBL-10 1
LCG-10,18 5
MBB-10 14
MBG 6 1
MBG-10 18 8 13 2 10 6 14 2 6 1 1
MBG-10,18 6
MBJ-10 1 2
MBR-10 14 12 1 1 3 2 3 6 1 12
MCB-10 2 1
MCD-10 2
MCG-10 6
MCH-10 2
MCR-10 3 3 1 5
MCR-10,18 3
MDB-10 1 1 2
MDG-10 1 1
MDR-10 7 6
MFB-10 1
MGB-10 1
PBG-18 2
PBJ-10,18 1
PBR-10,18 2 2
PNM-10,18 2
PNR-10 2 2
TBG 1
TBG-10 1 3
TDB-10 2
TDG-10 1 7
TFB-10 1 1 7
TFG-10 3 1
TLG-18 6 2 4 7 3 4 2
__________________________________________________________________
No. isol. 54 26 41 1 4 22 2 4 8 34 26 14 59 3
__________________________________________________________________
*Race Virulence formula
CBG-10,18 3,10,11,18
FBT-18 2c,3,3ka,11,17,18,30
FCD-10 2c,3,10,17,26
LBB-10,18 1,10,18
LBL-10 1,10,11
LCG-10,18 1,10,11,18,26
MBB-10 1,3,10
MBG 1, 3,11
MBG-10 1,3,10,11
MBG-10,18 1,3,10,11,18
MBJ-10 1,3,10,11,17
MBR-10 1,3,3ka,10,11,30
MCB-10 1,3,10,26
MCD-10 1,3,10,17,26
MCG-10 1,3,10,11,26
MCH-10 1,3,10,11,26,30
MCR-10 1,3,3ka,10,11,26,30
MCR-10,18 1,3,3ka,10,11,18,26,30
MDB-10 1,3,10,24
MDG-10 1,3,10,11,24
MDR-10 1,3,3ka,10,11,24,30
MFB-10 1,3,10,24,26
MGB-10 1,3,10,16
PBG-18 1,2c,3,11,18
PBJ-10,18 1,2c,3,10,11,17,18
PBR-10,18 1,2c,3,3ka,10,11,18,30
PNM-10,18 1,2c,3,3ka,9,10,18,24,30
PNR-10 1,2c,3,3ka,9,10,11,24,30
TBG 1,2a,2c,3,11
TBG-10 1,2a,2c,3,10,11
TDB-10 1,2a,2c,3,10,24
TDG-10 1,2a,2c,3,10,11,24
TFB-10 1,2a,2c,3,10,24,26
TFG-10 1,2a,2c,3,10,11,24,26
TLG-18 1,2a,2c,3,9,11,18
Wheat stripe rust
The first report of wheat stripe rust in the central U.S. was in early
April in southeastern Arkansas. By mid-April, stripe rust was found in
fields in central Arkansas and by the last week in April, traces of
stripe rust were found in plots of southern soft red winter wheat
cultivars in north central Texas. In mid-May, stripe rust was found in
a field of CK9835 in northwestern Arkansas and in a plot of soft red
winter wheat in south-central Kansas. During late June, wheat stripe
rust was light in Bozeman, Montana plots. In early July, traces of
wheat stripe rust were found in an irrigated winter wheat field in the
panhandle of Nebraska. Stripe rust generally is inhibited at
temperatures above 70 F, so in all cases in this area the disease
stopped developing with the onset of hot weather and losses were
minimal. Losses due to stripe rust in Kansas were at an all time high
for the disease at 0.01 percent.
During mid-April, stripe rust was observed in northwestern Washington
wheat fields and nurseries. In late April, 70% stripe rust severities
were reported in some northwestern Washington wheat fields and
nurseries, but losses were not significant in commercial fields with
adult plant resistance. During the first week in May, light amounts of
stripe rust were found in eastern Washington and eastern Oregon fields.
Dry weather in late May retarded stripe rust development until late
June. In early July, stripe rust was severe in plots of susceptible
winter wheat in eastern Washington, but again stripe rust was not a
problem in commercial fields with adult plant resistance.
In California, in late April, wheat stripe rust was light in San Joaquin
Valley fields and Sacramento Valley plots. Stripe rust developed late
and was less severe than normal for this area.
Oat stem rust
Oat stem rust was observed in varietal plots in southern Louisiana in
late February. In general there was less oat stem rust and development
was slower in this area than last year because of the cool conditions in
February and early March. Even though the rust developed later than
normal, the rust still destroyed some of the southern Louisiana oat
plots. During the last week in June, 2% oat stem rust severities were
observed in a northeastern Indiana nursery.
During the last week in March, oat stem rust overwintering sites (trace
to 20% severities) were found in varietal plots in nurseries at Beeville
and Temple, Texas and in a field 50 miles southwest of San Antonio. In
the last week of April, trace to 20% severities were reported in oat
plots in central and north-central Texas. Traces of oat stem rust were
also found in central Texas fields and on wild oat (Avena fatua) plants
growing along the roadside. By the first week in May, oat stem rust
was severe in north-central Texas plots. The amount of rust in this
area was greater than in 1994, but within the normal range for stem rust
development on oats in Texas. The relative lack of oat acreage in the
central Great Plains tends to interrupt potential epidemics of oat stem
rust farther north unless stem rust is extremely severe in southern
Texas.
The first detection of oat stem rust in the northern central plains this
year was during the first week in July when traces of oat stem rust were
found on wild oat (Avena fatua) plants growing alongside the road in
southeastern North Dakota. In mid-July, traces of oat stem rust were
found in plots in east central Minnesota, but no rust was found on a
disease survey throughout eastern South and North Dakota. Much less oat
stem rust was found in the northern Great Plains this year than in
previous years. The reduced amount of oat stem rust seems to be
associated with a decline in oat production. Oat acreage in the United
States is projected to be the lowest since records began in 1866.
Losses to oat stem rust were minimal in the northern oat-growing area
this year.
Race NA-27, virulent to Pg-1,2,3,4, and 8, remains the predominant race
of the oat stem rust population (Table 3). The other races identified
so far in 1995 are NA-16 which is virulent to Pg-1,3,and8, and NA-5
which is virulent to Pg-3 and 15.
TABLE 3. Oat stem rust races identified through August 8, 1995
__________________________________________________________________
Number of Number of isolates of NA race*
______________________ __________________________________
State collections isolates NA-5 NA-16 NA-27
___________________________________________________________________
AR 1 3 3
CA 2 6 6
GA 1 3 3
LA 1 3 3
TX 59 164 25 139
___________________________________________________________________
Oat crown rust
During the last week in March, severe crown rust was observed in many
southern Texas nurseries and fields. In some fields south of San
Antonio, 40% severities were common, while in late maturing cultivars in
southern Texas nurseries, the rust was so severe it stunted the plants.
The severe and widespread crown rust was comparable to last year's
severe rust development in the southern area of the U.S.
In late March, crown rust levels were much higher than normal in the
southeastern U.S. oat-growing area. In varietal plots crown rust was
severe (>40%) while in oat fields, severities were moderate (1-20%). In
mid-April, in southeastern U.S. varietal plots crown rust was severe
(>80%), while in oat fields severities were moderate (1-20%). In late
April, in southeastern U.S. varietal plots, crown rust killed the most
susceptible cultivars. By the first week in May, crown rust severities
ranged from traces to 90% in oat plots at soft dough from east central
North Carolina to central Louisiana. This was the most severe crown
rust ever observed in this large an area in the Southeast. In northern
Alabama, southern Tennessee, and northern Arkansas, however, crown rust
infection was light in mid-May. The warm temperatures and moisture in
the southeast were conducive for rust development. These southern areas
of infection provided inoculum for the limited acreage of northern oats
emerged by mid-May.
For the first time in the past 12 years crown rust was observed in the
oat nursery at Wooster, Ohio. By mid-June, severities ranged from
traces to 90% on the flag leaf. Also for the first time in 35 years,
crown rust was severe in the oat nursery near University Park in central
Pennsylvania.
During the third week in May, oat crown rust was just beginning to
appear on oats adjacent to buckthorn, the alternate host in the St.
Paul, Minnesota nursery. This was about 2 weeks later than normal. By
mid-June, oats growing near the buckthorn nursery at St. Paul were
severely infected. During the third week in June, trace to 10% crown
rust severities were found on lower leaves in southern Minnesota oat
plots. During early July, trace to 60% crown rust severities were found
on the flag leaves in oat plots in east-central Minnesota. In early
July, crown rust was light in southern Wisconsin but severe in eastern
South Dakota. In mid-July, trace-20% crown rust severities were found
on oat flag leaves throughout the eastern Dakotas, southern Minnesota
and southern Wisconsin fields. The most severe rust was found in fields
where rust occurred early and conditions were conducive for rust
development. Buckthorn growing in close proximity to oat fields
provided some of the initial inoculum in these areas, i.e., southern
Wisconsin and southern Minnesota. In mid-July, only traces of crown
rust were recorded in northwestern North Dakota plots. By early August,
20% severities were observed on flag leaves in the northwestern North
Dakota plots and in an irrigated nursery in northeastern Montana. In
early August, sixty-percent severities were common on wild oats (Avena
fatua) in northwestern Minnesota. Crown rust losses were severe in late
planted oats in Minnesota and the Dakotas.
In early June, heavy aecial infections were observed on buckthorn bushes in the area around Saskatoon, Canada. However, only traces of crown rust were observed in plots by August 8. In mid-June, oat spreader plots in a buckthorn nursery in southern Ontario were heavily infected with crown rust.
During the second week in May, crown rust was light in oat fields at
late milk stage in the Central Valley of California. During the third
week in May, 60% crown rust severities were in observed in Davis,
California oat plots.
The incidence of virulence for 1995 crown rust isolates tested to date
is presented in Table 4.
TABLE 4. Incidence of virulence in 1995 oat
crown rust isolates tested to date (8-8-95)
_________________________________________________
Percent of isolates virulent
____________________________
Differential AL, FL, GA LA TX
_________________________________________________
Pc 14 77 73 81
Pc 35 82 75 44
Pc 36 36 32 43
Pc 38 14 18 24
Pc 39 9 8 22
Pc 40 86 77 93
Pc 45 5 7 6
Pc 46 36 45 57
Pc 48 9 0 0
Pc 50 32 21 43
Pc 51 77 79 78
Pc 52 9 0 0
Pc 53 0 1 0
Pc 54 23 36 10
Pc 56 27 32 38
Pc 57 14 26 18
Pc 58 TAM-O-301 32 46 14
Pc 59 TAM-O-312 55 74 17
Pc 60 Coker 227 86 78 82
Pc 61 Coker 234 86 70 79
Pc 62 0 1 0
Pc 63 9 8 21
Pc 64 0 10 3
Pc 67 32 44 76
Pc 68 0 3 0
Pc 70 10 12 19
Pc 71 9 10 24
H548 5 1 0
Dane 5 3 6
WI X4361-9 5 7 1
TAM-O-386R 0 4 16
TAM-O-393 0 5 3
Mitchell 89 73 82
_________________________________________________
No. of isolates 22 73 68
Barley crown rust
Light crown rust infections were found this year in east central and
southwestern Minnesota plots.
Barley stem rust
In late April, traces of stem rust were found in a barley plot in north-
central Texas. Limited amounts of barley are grown commercially in the
southern and central plains states and generally only traces of stem
rust are found in this area. In early July, barley stem rust was
reported for the first time in the northern barley-growing area as
traces were found in a southeastern North Dakota field. Traces of
barley stem rust were also found on wild barley (Horde jubatum) growing
alongside a road in southeastern North Dakota. In early August, trace-
10% severities were common in fields and plots in northeastern North
Dakota and northwestern Minnesota. This is the most barley stem rust
that has been reported in the last five years in this area. This year
barley stem rust will cause losses in late-planted fields.
Barley leaf rust
By the last week in March, severe leaf rust caused by Puccinia hordei
was observed on barley plots in south Texas. During the last week in
April, 20% barley leaf rust severities were observed in central Texas
plots and traces in north-central Texas plots. Leaf rust is generally a
minor barley disease in the southern plains.
In early June, leaf rust was severe on barley in southeastern Nebraska
plots. By the third week in June, 20% severities were found in east-
central Nebraska plots and traces in southern Minnesota plots. During
mid-July, light barley leaf rust (<10%) was found in southern and west
central Minnesota plots and in a field in central Minnesota. By early
August, trace-5% severities were common in barley fields and plots in
northeastern North Dakota and northwestern Minnesota. Severities up to
40% on individual leaves were found within fields in northeastern North
Dakota. There is more barley leaf rust in this area than in the last
three years.
In mid- May, leaf rust was found on barley near Jackson in western
Tennessee. By the first week in June, barley leaf rust severities were
greater than 5% in central Michigan fields.
In early May, near Guelph, Ontario, Canada, secondary spread of barley
leaf rust was starting where rust overwintered in plots. In early June,
barley leaf rust was severe on some winter barleys in a nursery in
southern Ontario.
During the third week in May, barley leaf rust was severe on barley
growing in Davis, California plots.
This year in the U.S., losses to barley leaf rust were minimal.
Barley stripe rust
In late March, traces of stripe rust on barley were reported in nursery
plots in Uvalde and Beeville, Texas and in a field 30 miles southwest of
San Antonio, Texas. During the second week in May, stripe rust was
found on green flag leaves in barley plots in the San Joaquin Valley of
California. This year in the Sacramento Valley, California barley
nurseries, stripe rust was much more widespread because of the cooler
than normal conditions. In late May, barley stripe rust was found in
western Oregon and western Washington plots. The rust was scattered
throughout the plots and in one instance there was a hot spot where the
rust severities reached 80%. Greenhouse tests confirmed this was barley
stripe rust on barley. In early June, in the Skagit Valley of
Washington, 10% severities were found in some barley plots. In early
July, severe barley stripe rust was reported in fields in the Klamath
Valley of south central Oregon and light severities in south central
Idaho fields. In mid-July, light barley stripe rust was found scattered
throughout the nurseries at the Pullman, Washington experiment station.
This was the most barley stripe rust ever seen at this location.
In 1995, barley stripe rust was reported from Texas to Washington. The
first report of barley stripe rust ever being found in the U.S was in
the spring of 1991 in southern Texas. Barley stripe rust now seems
firmly established in the Pacific Northwest, where the climate is most
favorable for its development. This is a perfect example of a disease
finding its niche and increasing at a fast rate over a large area.
Rye stem rust
In late April, traces of rye stem rust were reported in central Texas
plots. In early August, 1% stem rust severities were reported in a rye
plot in west central Minnesota.
Rye leaf rust
During the last week in March, 40% rye leaf rust severities were
observed in plots and fields in southern Texas. In the last week of
April, trace to 5% severities of rye leaf rust were found in fields and
plots in north-central Texas. During the third week of May, in two
north-central Oklahoma rye fields, 40% leaf rust severities were
observed. In early May, 20% severities were found on winter rye in
south-central Kansas.
During early May, traces of leaf rust were found on winter rye plots at
Rosemont, Minnesota. In mid-June, winter rye in a southeastern North
Dakota field was heavily rusted (20-40% severity), suggesting the rust
overwintered, while rye in fields 5 miles away were free of rust.
During the first week in July, 60% rye leaf rust severities were
observed on winter rye flag leaves and 10% severities were observed on
spring rye flag leaves in east central Minnesota varietal plots. In
mid-July, 20% rye leaf rust severities were observed in southern and
west-central Minnesota plots of the spring rye cultivar Prolific.
Crown rust on Buckthorn
As of May 15, no aecial infections were found on buckthorn bushes
growing on the University of Minnesota St. Paul campus. In normal
years, crown rust aecia appear in late April in St. Paul. The
abnormally cool spring delayed bud break of buckthorns until early May
and, apparently, also delayed germination of crown rust teliospores.
Aecial infections on buckthorn were heavy in northern Iowa and southern
Minnesota this year, but light in Wisconsin and Illinois. Aecial
infections varied from light to heavy in North Dakota. In early June,
aecia were found on buckthorn bushes in Winnipeg, Canada. For the first
time in recent years, aecia were found on buckthon at Saskatoon, Canada.
Stem rust on Barberry
During the first week in June, the aecial stage of stem rust was found
on common barberry (Berberis vulgaris) bushes in southeastern Minnesota
and south-central Wisconsin in Dane County. During the last week in
June, rust aecia were found on leaves of barberry (Berberis fendleri)
bushes growing along a trail in the Rio Grande National Forest in south-
central Colorado. The rust has not been positively identified yet. It
is probably not stem rust, but more likely is a species limited to wild
grasses.
Rust on Grasses
During the last week in April, light amounts of stem rust were observed
on fescue in north-central Texas. Also, during the last week in April,
crown rust was found on ryegrass and fescue and leaf rust on little
barley (Hordeum pusillum) in southern Georgia. During the third week in
July, severe (65% severity) stem rust was found on quackgrass (Agropyron
repens) that was growing within 100 yards of the common barberrry
(Berberis vulgaris) in southeastern Minnesota.
This is the last issue of the Cereal Rust Bulletin for the 1994-95
growing season. I would like to thank all of those who helped with the
bulletin this year, especially Mark Hughes who coordinates its
distribution through e-mail (markh@puccini.crl.umn.edu). As most
universities and research facilities now have access to Internet, we
would like to use this system for exchanging information. Any reports
of rust that you find in your area will be appreciated and this
information will be added to the CRB. My user name is
davidl@puccini.crl.umn.edu.
As you no doubt know, all Federal Government agencies are reviewing
their program priorities. If you feel that this publication and the
related activities of the Cereal Rust Lab are important to you, you can
help us by calling the USDA, ARS Midwest Area Director, Dr. Richard
Dunkle, 1815 N. University Street, Peoria, IL 61604, phone# 309-681-
6602 (Internet address: !A03ADMWA@ATTMAIL.COM). Dr. Dunkle will be glad
to discuss how you can make your feelings known in Washington.
Your comments on any aspect of the Cereal Rust Bulletin are welcome.
- David L. Long