A Database for Triticeae and Avena
Barley Genetics Newsletter (2005) 35:23 - 26
Races of Puccinia striiformis
f. sp. hordei, the pathogen of barley
stripe rust in the United States in 2004
and Laura Penman2
Wheat Genetics, Quality, Physiology, and Disease Research Unit and
of Plant Pathology, Washington State University, Pullman, WA 99164-6430.
Stripe rust of barley, caused by Puccinia striiformis f. sp. hordei
(PSH), occurred mainly in California, Idaho, Oregon, and Washington and caused
localized damage to barley crops. Growing cultivars with high-temperature, adult-plant resistance and
the cropping system contributed to the low level of stripe rust. Stripe rust samples were collected from the
four states and tested under controlled greenhouse conditions on seedlings of a
set of 12 barley genotypes used to differentiate races of the fungal
pathogen. A total of 15 races were detected,
of which three were new. PSH-72, a new
race, was virulent on all 12 differential genotypes. The most predominant race was PSH-71 that was virulent on
differential genotypes Topper, Emir, Hiproly, Varunda, Abed Binder 12, Trumpf,
Mazurk, Bigo, and Bancroft.
Westend. f. sp. hordei Eriks., the
causal agent of barley stripe rust, has established in the United States since
it was first reported in southern Texas in 1991 (Marshall and Sutton, 1995;
Roelfs et al., 1992). In the early
1990s, the disease occurred in the south central states and later spread to the
states west of the Rocky Mountains (Chen et al., 1995). The disease has caused major damage to
barley crops in the U.S., mainly in California and the Pacific Northwest (Brown
et al., 2001; Chen, 2004).
Chen et al.
(1995) selected 11 barley genotypes for differentiating races of P. striiformis f. sp. hordei. Later, the barley cultivar ‘Bancroft’ was added to the
differential set (Chen and Line, 2001).
Using the differential genotypes, 69 races were identified from the
early 1990s to 2003 (Chen et al., 1995; Chen and Line, 2001; Chen, 2004). The objectives of this study were to 1) monitor
the occurrence and distribution of barley stripe rust and 2) identify races and
determine their frequencies and distributions in the United States in 2004.
Materials and Methods
stripe rust. Stripe rust was monitored by surveying
commercial fields during the growing season.
Trap plots consisting of the set of differential genotypes (Table 1) and
other cultivars either susceptible or resistant to P. striiformis f. sp. hordei
were planted at various locations. For commercial
field survey, infection type, severity (percentage of leaf areas infected),
prevalence (percentage of plants infected), and information on cultivar,
location, and growth stage were recorded.
For the trap plots, infection
type and severity were recorded one to three times during the growing
season. Stripe rust infected leaf
samples were collected for race identification.
Race identification. Races of stripe rust samples were
determined using a set of differential genotypes following the methods
described by Chen et al. (1995). In
this study, 12 barley genotypes (Table 1) were used to differentiate races of P. striiformis f. sp. hordei. Samples of infected leaves that
were usually shipped in glassine envelops were used to inoculate seedlings of ‘Steptoe’
or ‘Topper’, which are susceptible to all races of P. striiformis f. sp. hordei,
for increasing urediniospores. For
samples of poor quality (received more than 7 days after collection or with limited
uredia), leaf pieces were placed on moist filter paper in a Petri dish that was
kept at temperatures of 4-12oC overnight. Fresh spores produced on the leaves were used in inoculation for
plants were kept in a dew chamber at 10oC for 18 to 24 hours for
infection and then grown in a greenhouse growth chamber at a diurnal
temperature cycle gradually changing from 4oC at 2:00 am to 20oC
at 2:00 pm. The light period consisted
of day light supplemented with metal halide lights to extend the photoperiod to
16 hours. Urediniospores that were
collected 16 to 30 days after inoculation were used to inoculate seedlings of
the set of differential genotypes.
Inoculated plants were kept in the dew chamber for infection and then grown
in a growth chamber for symptom development under the same conditions as described
for the spore increase. Infection type
(IT) data were recorded 18-22 days after inoculation according to the 0-9 scale
described by Line and Qayoum (1991).
Isolates that produced ITs 0 - 5 were considered avirulent and 6 - 9
were considered virulent on individual barley differential genotypes. New races that had virulence patterns
different from previously identified races were confirmed at least in one more
test with the differential genotypes. Frequency
of each race was determined as percentage of the isolates that were identified
as that race from the total of isolates in the study.
Table 1. Barley
genotypes used to differentiate races of Puccinia
striiformis f. sp. hordei
Abed Binder 12
and Line (2003).
stripe rust occurred in California, Oregon, Washington, and Idaho. Of a total of 39 viable isolates of P. striiformis f. sp. hordei, 18 were obtained from
California, 3 from Oregon, 13 from Washington, and 5 from Idaho. All isolates were from barley (Hordeum vulgare) cultivars, except for
one isolate that was collected from wild barley (H. spontaneum) in California. The isolate from wild barley was identified as race PSH-33 that
was virulent only on two (Topper and Abed Binder 12) of the differential
genotypes. As shown in Table 2, a total
of 15 PSH races were identified, of which three were new and designated as
PSH-70, PSH-71, and PSH-72 (Table 3). PSH-70 was virulent on four (Topper, Abed Binder 12, Bigo, and
Bancroft) of the 12 differential genotypes.
PSH-71 was virulent on nine (Topper, Emir, Hiproly, Varunda, Abed Binder
12, Trumpf, Mazurk, Bigo, and Bancroft).
PST-72 was virulent on all 12 differential genotypes. Of the 15 races, nine were presented by only
one isolate, one by two isolates, three by four isolates, one by five isolates,
and one by 14 isolates. Although PSH-71
was new, it was the most predominant race.
Nearly 85% of the isolates were collected from disease monitoring and
germplasm screening nurseries. Only 15%
of the isolates were obtained from commercial fields, indicating that the
severity levels of stripe rust in commercial field were generally low.
stripe rust incidence was relatively low compared to wheat stripe rust in
2004. The barley yield losses due to
stripe rust were estimated as 63,000 bushels in the four states (http://www.cdl.umn.edu/loss/loss.html). In contrast, wheat stripe rust had a much
wider spread and severer epidemic, which caused yield losses of about 6.6 million
plus millions of dollars spent on fungicide application in the four states. The relatively light stripe rust epidemic on
barley compared to wheat stripe rust epidemic in the Pacific Northwest were
attributed to 1) the smaller barley acreage, 2) the lack of winter barley,
which reduces rust inoculum from previous crops, and 3) the use of
high-temperature, adult-plant resistant cultivars such as Baronesse (Chen,
2004). In California, the reduced
barley acreage compared to that in early 1990s and growing resistant cultivars
have contributed the low level of stripe rust in the recent years.
stripe rust was generally light in commercial fields, susceptible cultivars in
various nurseries had up to 100% of severity in California and western
Washington. The disease monitoring data
suggest that stripe rust is still a threat to barley production in the western
United States. For this region, stripe
rust resistance should remain as one of the top priorities for barley breeding
Table 2. Races of Puccinia striiformis f. sp. hordei
(PSH) and their frequencies and distributions in 2004
CA(3), ID(1), WA(1)
CA(6), ID(2), WA(5)
CA(1), ID(1), OR(2)
Table 1 for the barley genotypes used to differentiate races of P. striiformis f. sp. hordei.
Table 3. New races
of Puccinia striiformis f. sp. hordei (PSH) detected in 2004, type
isolates, and dates, locations, and cultivars collected
We would like to thank Drs. Lee Jackson, Patrick Hayes, and
Don Obert for sending samples of barley stripe rust. We also like to thank David Long and Mark Hughes for compiling
yield loss data from various states. The financial support from USDA-ARS and Washington Barley
Commission is highly appreciated.
Brown, W. M. Jr,
Hill J. P., Velasco V. R. 2001. Barley yellow rust in North America. Annual Review of Phytopathol. 39:367-384.
Chen, X. M.
2004. Epidemiology of barley stripe
rust and races of Puccinia striiformis
f. sp. hordei: the first decade in
the United States. Cereal Rusts and
Powdery Mildews Bulletin 32: [www.crpmb.org/]2004/1029chen.
Chen, X. M., and Line, R. F. 2001. Races of barley stripe rust in the United States. Barley Newsletter 44. On-line at:
Chen, X. M., Line,
R. F., 2003. Identification of genes
for resistance to Puccinia striiformis
f. sp. hordei in 18 barley genotypes.
Chen, X. M., Line, R. F., Leung, H., 1995. Virulence and polymorphic DNA
relationships of Puccinia striiformis
f. sp. hordei to other rusts.
Dubin, H. J., and Stubbs, R. W., 1986. Epidemic
spread of barley stripe rust in South America. Plant Dis. 70:141-144.
Line, R. F., and Qayoum,
A., 1991. Virulence, aggressiveness, evolution, and distribution of races of Puccinia striiformis (the cause of
stripe rust of wheat) in North America, 1968-87. USDA-ARS, Technical Bulletin
1788, 44 pp.
Sutton, R. L., 1995. Epidemiology of
stripe rust, virulence of Puccinia
striiformis f. sp. hordei, and
yield loss in barley. Plant Dis. 79:732-737.
Roelfs, A. P.,
Huerta-Espino, J., and Marshall, D., 1992. Barley stripe rust in Texas.
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