Ground Cover North : Ground Cover 095 November-December 2011 - North
By Catherine Norwood n A new wheat disease identified in Brazil in 1985 was initially considered "something of an oddity" but is now seen as a potential time bomb, with sporadic outbreaks affecting successively larger areas in South America. The wheat blast pathogen, Magnaporthe grisea, can cause total crop losses. No existing wheat varieties have shown good resistance and chemical treatments to date have failed or had only limited success. Symptoms include Our future world relies on wheat Australian link Amid all the new activity and growth, Dr Lumpkin says CIMMYT is grateful for the sustained investment provided by Australia from the GRDC, which has supported projects to import and evaluate CIMMYT wheat germplasm for use in Australia since 1994, and through the Australian Centre for International Agricultural Research (ACIAR). "Australia -- which has been renowned for wheat breeding for more than a century -- is uniquely aware of the value of crop genetic resources," Dr Lumpkin says. "Australia's support is especially well received for many reasons -- for the budget, the consistency of support and for the mentality. We share similar attitudes to many things with Australia, especially in wheat breeding and development." Between the GRDC and ACIAR, Australia in 2010 provided US$6.7 million towards CIMMYT's US$65.5 million budget. And because of shared interests there is close collaboration with Australia on a range of projects including: n breeding for drought tolerance -- this includes crossing Australian lines noted for their drought tolerance with elite CIMMYT lines known for their yield stability, disease resistance and high yield potential; n provision and evaluation of rust-resistant wheat germplasm through the Australian Cereal Rust Control Program at the Plant Breeding Institute in Cobbitty, NSW; n breeding for resistance to soil-borne diseases, especially to cereal cyst, root lesion nematodes and crown rot; n transferring karnal bunt resistance genes into adapted Australian wheat lines in preparation for an incursion; and n the transfer of new dwarfing genes identified in Australia by CSIRO's David Bonnett to CIMMYT elite lines. Past investment has been beneficial to Australian farmers. More than 90 per cent of the wheat grown in Australia has ancestry that traces back to CIMMYT's genebank. The value of those genetic resources has been estimated at nearly $150 million a year. But looking to the future, Dr Lumpkin believes wheat production systems are coming under intensifying pressure from a combination of stresses. Prime concerns are heat stress, rising transportation costs, dwindling groundwater resources and disease pressure. He says impacts are already discernible, with subsistence farmers shifting from wheat to the more heat-tolerant maize, even in regions like the Indo--Gangetic Plains where there is no tradition of eating maize. South America is dealing with the outbreak of a new disease -- wheat blast -- that is devastating wheat crops (see article below). To date CIMMYT has detected little genetic resistance in wheat to blast and no effective fungicides. International collaboration NOVEMBER -- DECEMBER 2011 GROUND COVER 16 KEY POINTS n Wheat and maize farmers benefit from a near doubling in the budget of CIMMYT n Programs are underway to lift agricultural productivity, sustainability and resilience n Innovations are being sought through alliances with public and private sector breeders, through conservation agriculture, and socioeconomic services such as risk insurance n Past benefits to Australian wheat growers from links with CIMMYT estimated at $150 million a year from improved varieties alone The way the world is expected to look in 2050 is much on the mind of Dr Thomas Lumpkin, as the CIMMYT Director-General oversees efforts to build capacity within farming systems CIMMYT's head wheat pathologist Dr Etienne Duveiller has been tracking the spread of the deadly new wheat blast pathogen across South America for the past decade. (Left) A wheat-blast-affected crop in Parana during the 2009 Brazil epidemic. PHOTO: CATHERINE NORWOOD PHOTO: ETIENNE DUVEILLER. The Director-General of the International Maize and Wheat Improvement Center, Dr Thomas Lumpkin. NEW DISEASE HIGHLIGHTS UNCEASING CHALLENGE bleaching of ears and shrivelled kernels, with average losses of 40 to 50 per cent. The head wheat pathologist at the International Maize and Wheat Improvement Center (CIMMYT), Dr Etienne Duveiller, first saw wheat blast infection in Bolivia in 1993, and has since followed its intermittent outbreaks across Brazil, Bolivia and Paraguay. In 2009 a widespread outbreak in Brazil reduced the national wheat crop by an estimated 30 per cent. Visiting affected areas, Dr Duveiller said he had never seen anything like it in almost three decades as a plant pathologist. "Looking into the distance across the lowlands you could see whole crops wiped out." The disease appeared to come from nowhere, with widespread infection occurring in just three weeks. The wheat blast has been identified as a new fungal pathogen, related to rice blast, but not a mutation of rice blast as originally thought. Brazilian research indicates it is likely to have originated with tropical grasses in the region. Dr Duveiller says the sporadic nature of infections has made it difficult to study. "We still don't know much about it, in terms of epidemiology. We don't know if a sexual stage is occurring, where the inoculum comes from, or why there are outbreaks of such magnitude. So we could have five years with bits here and there, without much impact, and then suddenly there is an epidemic." All wheat varieties grown in Brazil have shown susceptibility, with some differences in response attributed to limited tolerance or avoidance. "We can see between different crops, or different paddocks, that just a few days' difference in planting can determine whether or not a crop escapes infection." The spread of the infection appears to be airborne. Dr Duveiller says there is an urgent need for epidemiological studies in the field, while CIMMYT's role is to identify sources of resistance for use in breeding programs. Genetic resistance will play a crucial role if chemical controls cannot be developed. "We don't have the right chemicals, or the right mode of action, partly because we don't understand the epidemiology, and the disease is not yet on the radar of chemical manufacturers to create an effective compound." CIMMYT has made identifying resistance to wheat blast a priority and is scanning its gene bank of 140,000 lines to identify potential germplasm candidates to be tested in affected areas. There are concerns the pathogen will spread beyond South America, despite the fact that there are limited countries with similar climatic conditions. However, Dr Duveiller says climate change may increase areas favourable to the pathogen. □ GRDC Research Code CIM00014 More information: International Maize and Wheat Improvement Center (CIMMYT), www.cimmyt.org PHOTO: BRAD COLLIS By Gio Braidotti n After decades of stagnating investment in its agricultural R&D program, the International Maize and Wheat Improvement Center (CIMMYT) has seen its budget nearly double in the past three years as food security concerns escalate worldwide. With the renewed financial support has come a bold new agenda that includes productivity goals that move well beyond previous strategic thinking. CIMMYT is responding to the unprecedented intensity of the stresses bearing down on farmers from the combined effects of population growth, climate change and diminishing natural resources, especially water. CIMMYT's Director-General Dr Thomas Lumpkin says that generous funding is now coming from non-traditional sources. Mexico, for example, is now CIMMYT's biggest donor nation and India has provided 500 hectares and funds to create the Borlaug Institute for South Asia, a new focal point for agricultural research and development in the region. The centre is also engaging in strategic alliances with several large agribusinesses -- including Syngenta, Pioneer HiBred and Monsanto -- which will donate their advanced technology to benefit smallholder farmers in Africa and Asia.
Ground Cover 096 January-February 2012 - North
Ground Cover 094 September-October 2011 - North