Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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Yellow rust virulence patterns in
Pakistan during 1998–2003, and
responses of some commercial
cultivars
Javed Iqbal Mirza, Iftikhar Ahmad, Atiq-ur-Rehman Rattu, Saif Khalid, M. Afzal
Akhtar, Lal Khan Khokhar, Munawar Hussain, Syed Javed Hamid, M.A.S. Kirmani
and Ehsan-ul-Haq
Crop Diseases Research Programme, Institute of Plant and Environmental Protection,
National Agricultural Research Centre, Park Road, Islamabad, Pakistan
Introduction
Like other parts of the world, wheat cultivated in Northern Punjab, NWFP and
Baluchistan is severely affected by stripe rust disease caused by Puccinia
striiformis f.sp. tritici West. Mehta (1940) concluded that yellow rust is the main
wheat disease of Punjab. Tahir (1978) found primary infections of yellow rust
in the foothills and the adjoining parts of Punjab during early January. Early
development of stripe or yellow rust is usually noted on susceptible cultivars
by mid-March, which develops to greater intensities by the end of April.
Cultivation of susceptible varieties can result in rust epidemics, with heavy
losses. It is thus very important to monitor the pathogen in the different wheat
growing areas of Pakistan. Particular virulence is found in the place where the
corresponding gene for resistance is in wide use (Kirmani et al., 1989). That is
why in a country like Pakistan, where the genetic basis of resistance against
yellow rust of wheat had always been narrow due to monoculture practices,
periodic epidemics have occurred as a result of the breaking down of
resistance in cultivars. Leading cultivars of the past, such as Mexipak, Pak 81,
Blue Silver and Pirsabak 91, succumbed to yellow rust disease of wheat, with
heavy losses.
Information on the changing virulence pattern of Puccinia striiformis is
critical to being able to manage yellow rust disease in the area. Trap nurseries
comprising near-isogenic lines are grown in different areas of Pakistan for this
purpose. The present study was conducted to achieve this goal so that efficient
deployment of resistant genes can be achieved to get maximum and prolonged
benefit from the effective yellow rust resistance genes.