Guest author: Colin Wellings, the international Stripe Rust Race

John Bakum
Wednesday, January 11, 2012

Colin Wellings, left, receiving the 2011 Farrer Award
Colin Wellings, left, receiving the 2011 Farrer Award
Stripe rust epidemics are a recurring threat to wheat yield in the majority of wheat growing regions of the world, with potential to inflict regular regional crop losses ranging from 0.1 to 5%, with rare events giving losses of 5 to 25%. Regions with current vulnerability include North America (particularly Pacific North West USA, Mexico), East Asia (China, north‐west and south‐west), South Asia (India, Pakistan, Nepal), Oceania (Australia, New Zealand), East Africa (Ethiopia, Kenya), the Arabian Peninsula (Yemen), Middle East (Syria, Turkey), Central Asia (Uzbekistan) and Western Europe. A basis for these epidemics has been the progressive emergence of pathogen races in similar patterns to that experienced in Australia. Collaborative work funded by ACIAR in association with international agencies CIMMYT and ICARDA allowed the development and deployment of genetic stocks to monitor race changes in the field across wheat regions in the developing world.

The Way Forward for the 'Stripe Rust Race'

The state, national and international importance of stripe rust demands the same focus on observation, collaboration and genetic resources that Farrer required more than a century ago in his seminal battle with the cereal rusts. Modern advances, such as in molecular technologies, are assisting in addressing important questions of pathogen variation and host resistance, but care must be taken not to be distracted from the primary objective. Farrer was distracted, for a time, by the less important but recurring leaf rust while the devastating stem rust was lost from focus; this was a deep regret for him. Likewise the study of contemporary stripe rust pathogen dynamics needs to be continually set in the context of breeding for resistance and disease management that together deliver practical farming outcomes.

Fungicides are being used increasingly in the management of foliar cereal diseases across large cultivated areas. The availability of offpatent generic products has brought an economic advantage to this management strategy, although a concern with the increasing usage of fungicides is the potential appearance of insensitive pathogen isolates. This concern becomes more focused with the awareness that the same mode of action applies to the entire suite of curative fungicides currently in the market place.

Breeding for resistance remains the most practical and cost effective means for containing stripe rust on farm, across states and within broader international regions. The approach to achieving resistance that is commercially successful is clear. However, the means of securing the necessary genetic diversity of resistance are becoming increasingly tenuous with the demands of protecting private investments in plant breeding and the increasing barriers that impede international exchange of germplasm. Investments in public‐good research and development have been a mainstay for advances in sustainable agricultural production in NSW and Australia. A long term, relevant and focussed research program has delivered services to the cereal breeding and farming communities that have addressed practical disease control strategies for stripe rust and shown global leadership in the pursuit of genetic solutions to the cereals.Commitment to build on this base will allow the cereal industries to maintain rust control while maximising seasonal opportunities.

Dr. Colin Wellings, Associate Professor at The University of Sydney and Principal Research Scientist with New South Wales Department of Primary Industries, was awarded the 2011 Farrer Medal. William Farrer is the famous ‘father’ of the Australian wheat industry and is best remembered as the breeder of the variety Federation and for significant improvements in Australia's wheat harvest. The medal is awarded annually to a person who has provided distinguished service in agricultural science in the areas of research, education, extension or administration. The preceding is excerpted from Dr. Welling’s acceptance speech.