Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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Eritrea, Tajikistan, Uzbekistan and Kyrgyzstan during previous years (Singh,
Duveiller and Huerta-Espino, 2004; Afshari, 2004). It has brought over
11 million hectare of the wheat growing area of India and Pakistan alone under
threat of yellow rust epidemics, due to cultivation of three most important
cultivars—Inqilab 91, MH 97 and PBW 343 (Attila)—possessing Yr27. In
addition to this, almost all the commercial wheat cultivars, particularly
Sarsabz, T.J.-83, Soghat 90, Anmol, Kiran 95 and Mehran 89, cultivated in
Sindh province; Kohistan, Parwaz, Bhakhar, Bahawalpur 97, Faisalabad 83,
Chakwal 97, Watan, SH 2002, Pasban 90 and Uqab 2000 cultivated in Punjab
province; Zargoon 79, Zardana and Sariab 92 under cultivation in Baluchistan
province; and Nowshera, Takbeer and Tatara cultivars of NWFP, are also
showing varying degree of susceptibility to this virulence. Singh, Duveiller
and Huerta-Espino (2004) reported that wheat cultivars, either selections or
derivatives of CIMMYT germplasm Attila, Opata, Kauz, Nacozari, Bucbuc and
Crow, grown across the CWANA region, are under threat of yellow rust
epidemic due to this new virulence.
In India, the race virulent on Yr27 has been designated as 78S84
(Anonymous, 2002a) and as 166E134A+ in Iran (Afshari, 2004). E. Duveiller,
during the Annual Wheat Meeting in Islamabad in 2003, with reference to Ravi
Singh of CIMMYT, reported that Inqilab 91 and MH 97 possess only Yr27 and
no Yr9, while PBW 343 and Bakhtawar 93 possess both Yr27 and Yr9. During
2002/03 and 2003/04, Inqilab 91, MH 97 (Attila) and PBW 343 have shown
susceptibility to yellow rust, while Bakhtawar 93 (Kauz), along with newly
released wheat variety Marvi 2000, were found free of yellow rust in rustprone
areas of NWFP. According to E. Duveiller of CIMMYT, these results
suggest the prevalence of two virulences: one attacking Yr27 alone and another
attacking Yr27+Yr9. However, the latter race attacking PBW 343 should have
attacked Bakhtawar 93. Besides, Yr27 virulence is also capable of attacking
Tandojam 83 (Nacozari), Opata, Bucbuc and Crow (Singh, Duveiller and
Huerta-Espino, 2004).
Susceptibility of Inqilab 91 to yellow rust has created a very alarming
situation for sustainability of wheat production in Pakistan. Since release,
Inqilab 91 has been very popular amongst growers due to its wide adaptability
and high yield potential under different sowing dates and different cropping
systems, like cotton-wheat, rice-wheat and sugarcane-wheat. Initially
Inqilab 91 was released for cultivation in southern parts of Pakistan due to rust
concerns, but it spread all across Pakistan and at the time of writing covered
about 60–70% of the area under wheat in Pakistan (Anonymous, 2004).
Inqilab 91 has shown yellow rust development in patches in Punjab since its
release, but no widespread epidemic has developed. This is mainly attributed
to the check on rust development provided by the slow-rusting and APR
mechanism of Inqilab 91. However, during 2002/03 and 2003/04 heavy rains
and prolonged low temperature resulted in epidemics of yellow rust on