Race Summary of Puccinia striiformis f sp tritici (the Wheat Stripe Rust Pathogen) and P. striiformis f sp hordei (the Barley Stripe Rust Pathogen) in the United States in 2013

Race Summary of Puccinia striiformis f. sp. tritici (the Wheat Stripe Rust Pathogen) and P. striiformis f. sp. hordei (the Barley Stripe Rust Pathogen) in the United States in 2013

1. 
   Samples. A total of 481 stripe rust samples were collected from wheat (446), barley (28), grasses (5), and triticale (2) from 28 states of the US and Ontario province of Canada. From the samples, 417 P. striiformis f. sp. tritici (Pst) and 26 P. striiformis f. sp. hordei (Psh) isolates were obtained.
   

2. 
   Differential sets: All of the Pst isolates were tested on a new set of 18 differential lines each with a single Yr gene and the barley isolates were tested on the set of 12 barley lines.
   

3. 
   Number of Pst races: From the 417 Pst isolates, 34 races were identified. The virulence spectra of the races ranged from 0 to 13 of the 18 Yr genes.
   

4. 
   The top five Pst races:
   

PSTv-52 (Code: 373242) (virulent to Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44, YrExp2; and avirulent to Yr1, Yr5, Yr10, Yr15, Yr24, Yr32, YrSP, YrTr1, YrTye), increasing from No. 4 (9.4%) in 2012 to No. 1 (39.2%) in 2013.

PSTv-37 (Code: 373244) virulent to Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44, YrTr1, YrExp2, and avirulent to Yr1, Yr5, Yr10, Yr15, Yr24, Yr32, YrSP, YrTye); decreasing from No. 1 (47.5%) in 2012 to No. 2 (13.2%) in 2013.

PSTv-73 (Code: 373246) (virulent to Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44, YrExp2, YrTye; and avirulent to Yr1, Yr5, Yr10, Yr15, Yr24, Yr32, YrSP, YrTr1), increasing from (0%) in 2012 to No. 3 (8.4%) in 2013.

PSTv-11 (Code: 573246) (virulent to Yr1, Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44, YrExp2, YrTye; and avirulent to Yr5, Yr10, Yr15, Yr24, Yr32, YrSP, YrTr1), decreasing from No. 2 (11.7%) in 2012 to No. 4 (7.7%) in 2013.

PSTv-14 (Code: 573247) virulent to Yr1, Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44, YrTr1, YrExp2, YrTye; and avirulent to Yr5, Yr10, Yr15, Yr24, Yr32, YrSP), decreasing from No. 3 (10.0%) in 2012 to No. 5 (4.8%) in 2013.
The top three races (PSTv-52, PSTv-37, and PSTv-73) were detected in both the western and eastern U.S., while PSTv-11 and PSTv-14, which were predominant in the western U.S. in 2010, 2011 and 2012, but in the eastern U.S. only detected in 2012, were not detected again in the eastern U.S. in 2013.

5. 
   New races. The following eight “new” races, which were not detected in 2010 - 2012, were detected in 2013:
   

PSTv-72 (Code 375742; virulent to Yr6, Yr7, Yr8, Yr9, Yr10, Yr17, Yr24, Yr27, Yr32, Yr43, Yr44, and YrExp2) is similar to a previously predominant race (PSTv-41) in the western U.S., but avirulent to YrTr1.

PSTv-73 (Code 373246; virulent to Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44, YrExp2, and YrTye) is similar to PSTv-52, but virulent to YrTye.
PSTv-74 (Code 533223; virulent to Yr1, Yr6, Yr9, Yr17, Yr27, Yr44, and YrTye) is similar to PSTv-44, but virulent to Yr44.
PSTv-75 (Code 343042; virulent to Yr6, Yr7, Yr8, Yr17, Yr43, Yr44, and YrExp2) is similar to PSTv-35, but avirulent to Yr9 and YrTr1.
PSTv-76 (Code 573242; virulent to Yr1, Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44, and YrExp2) is similar to PSTv-11, but avirulent to YrTye.
PSTv-77 (Code 533065; virulent to Yr1, Yr6, Yr9, Yr17, Yr44, YrSP, YrTr1, and YrTye) is close to PSTv-4, but virulent to Yr44 and YrTr1 and avirulent to Yr27.
PSTv-78 (Code 340242; virulent to Yr6, Yr7, Yr8, Yr27, Yr43, Yr44, and YrExp2) is similar to PSTv-36, but avirulent to Yr9 and YrTr1.
PSTv-79 (Code 150020; virulent Yr1, Yr7, Yr9, and Yr44) is close to PSTv-43, but avirulent to Yr8, Yr27, and YrTye.

6. 
   Resistance of Yr5 and Yr15. No races were found virulence to Yr5 and Yr15, and therefore, these two genes are still effective against all races identified so far in the U.S.
   

7. 
   Races of the barley stripe rust pathogen. Six races (PSH-33, PSH-46, PSH-48, PSH-58, PSH-71, and PSH-74) were identified with PSH-48 (42.3%) and PSH-33 (34.6%) as the most predominant races in 2013, which were also the top two races in 2012. The two predominant races are virulent only on 1 (PSH-48) and 2 (PSH-33) of the differentials. No new races were detected.
   

Excel data and summary tables:

1. 
   PSTsum13 including the following worksheets:
   
   1. 
      Summary data of Pst isolates
      
   2. 
      Summary data of Pst isolates by states
      
   3. 
      Summary data of Pst isolates by epidemiological regions
      
   4. 
      All PSTv races, frequencies, and distributions
      
   5. 
      PSTv races and frequencies in various states
      
   6. 
      PSTv races and frequencies in various epidemiological regions
      
   7. 
      Frequencies of virulence to Yr genes used as differentials
      
   8. 
      “New” PSTv races, codes, virulence formulae, type isolates, and detected states, regions and varieties.
      
2. 
   PSHsum13 including the following worksheets:
   
   1. 
      Summary data of Psh isolates
      
   2. 
      Summary data sorted by races
      
   3. 
      All PSH races, frequencies, and distributions