Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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virulent pathotypes. Since detection, Yr9+27 pathotypes steadily increased due
to increase in area under PBW 343. For the last two seasons (2006/07 and
2007/08), this pathotypes was the most prevalent and the only one to
predominate in the entire NWPZ region. Last year, its build up caused damage
to wheat yields of this region. Adult plant evaluation of cultivated wheat
revealed that few of these cultivars had a vertical resistance gene. For example,
HD 2329, HD 2733, HP 1633, Sonalika, VL 61 and HS 240 expressed resistance
against Yr9+27 pathotypes, indicating that these wheats carry a vertical
resistance gene(s) (Table 1). Multi-pathotyping tests of these cultivars have
indicated the presence of a cv. Avocet gene that is responsible for adult plant
resistance. Both PBW 343 and PBW 373 exhibited seedling resistance against
Yr9+27 pathotypes, which is due to Yr27 postulated in these cultivars.
WH 1021 carried an unknown gene that is imparting seedling resistance.
Further studies are needed to identify this resistance. Five wheats, namely
HS 277, DL 803-3, DWR 162, Macs 2496 and VL 738, were susceptible at
seedling and adult plant stage, indicating lack of a resistance gene in these
cultivars. The remaining wheats were found susceptible at the seedling stage
and showed resistance at the adult plant stage. It is evident that these carry
adult plant resistance gene(s). We suggest that the resistance of these lines be
used to minimize wheat yield losses in this region. Both DBW 17 and PBW 550
have been registered and suggested as replacements for PBW 343. The gradual
replacement of PBW 343 with these resistant varieties will certainly reduce
severity and incidence of yellow rust in the region.
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