Evaluation location: Washington, United States
Seedling Reaction to Stripe Rust. Greenhouse experiment. Recorded 20-22 days after inoculation of seedlings at the 2-leaf stage. Infection type (IT) of the basic scale (2, 5, 8) in the 0-9 scale was used. IT 2 (resistant) included IT 0 (no visible symptom or signs), IT 1 (necrotic and/or chlorotic flecks; no sporulation), IT 2 (necrotic and/or chlorotic blotches; no sporulation) and IT 3 (Necrotic and/or chlorotic blotches; trace sporulation); IT 5 (intermediate) included IT 4 (necrotic and/or chlorotic blotches; light sporulation), IT 5 (necrotic and/or chlorotic blotches intermediate sporulation) and IT 6 (necrotic and/or chlorotic blotches; moderate sporulation); and IT 8 (susceptible) included IT 7 (necrotic and/or chlorotic blotches; abundant sporulation), IT 8 (chlorosis behind sporulating area; abundant sporulation) and IT 9 (no necrosis or chlorosis; abundant sporulation) of the expanded 0-9 scale. The combination of races PST-17 (virulent on differentials 1,2,3,9,11), PST-37 (virulent on 1,3,6,8,9,10,11,12), PST-43 (virulence on 1,3,4,5,12,14), PST-45 (virulent on 1,3,12,13,15), and PST-100 (virulent on 1,3,8,9,10,11,12,16,17,18,19,20) covers all virulences detected in the US. The current 20 wheat genotypes used to differentiate races of Puccinia striiformis f. sp. tritici are: 1 = Lemhi (Yr21), 2 = Chinese 166 (Yr1), 3 = Heines VII (Yr2, YrHVII), 4 = Moro (Yr10, YrMor), 5 = Paha (YrPa1, YrPa2, YrPa3), 6 = Druchamp (Yr3a, YrDru, YrDru2), 7 = Yr5 (Yr5 in AVS; previously Riebesel 47/51), 8 = Produra (YrPr1, YrPr2), 9 = Yamhill (Yr2, Yr4a, YrYam), 10 = Stephens (Yr3a, YrSte, YrSte2), 11 = Lee (Yr7, Yr22, Yr23), 12 = Fielder (Yr6, Yr20), 13 = Tyee (YrTye), 14 = Tres (YrTr1, YrTr2), 15 = Hyak (Yr17, YrTye), 16 = Express (Yr?), 17 = Yr8 (Yr8 in AVS), 18 = Yr9 (Yr9 in AVS), 19 = Compair (Yr8, Yr19), and 20 = Clement (Yr9, YrCle). PST-100 was the most predominant race throughout the US in 2004 and 2005. (Order #170880)