Improving understanding and management of rice pathogens in Cambodia

• Cambodia Agricultural Research and Development Institute, Cambodia
• Charles Sturt University, Australia

Rice is the main staple crop in Cambodia. Average consumption is about 160 kg per person each year. As a result rice is planted on 90 per cent of the total agricultural area. Rice is also the major agricultural income earner. Diversification of agriculture beyond rice is an important priority for Cambodia's government, but to achieve this several factors must be addressed, including raising rice yields so some land can be freed up to other agricultural pursuits.

Average yields for rice in Cambodia vary from wet to dry season. In the wet season yields are around 0.95 tonnes per hectare, almost doubling to 1.8 t/ha in the dry season. One factor constraining wet season yields is disease, with this also limiting potential in dry seasons too. Current efforts to boost yields include double cropping of rice, a situation that also doubles the opportunities of diseases to spread.

Little is known about the spread or prevalence of important rice diseases in Cambodia. In part this is due to the lack of knowledge and expertise of plant pathology amongst Cambodian researchers. With more than 50 known diseases of rice capable of limiting yields, such knowledge is vital. What is known is the presence of brown spot, rice blast, false smut, kernel smut and bakanae. Building Cambodian capacity in plant pathology, focusing on rice is needed to support both increased production and the options for agricultural diversification.

The primary goal of the project is to initiate and develop Cambodian training in general plant pathology and more specifically rice plant pathology to build Cambodia's long term agricultural research capacity. The secondary aim is for Australian plant pathologists to gain a better understanding of the exotic diseases that have been identified as a threat to the Australian rice industry. It is intended that the knowledge gained form this project will help the Australian industry to maintain its comparative low-disease status and to prepare incursion management strategies.

Upgrade expertise and CARDI facilities for plant pathology to increase diagnostic capacity and capacity in plant pathology research and development with an emphasis on rice.
Develop and implement an effective training program in Australia and Cambodia to address Cambodian researcher needs.
Upgrade the CARDI plant pathology laboratory to support disease identification and plant pathology research and development and support on-the-job training in plant pathology through involvement in various research programs.

Collect, identify and curate herbarium specimens and isolates of pathogens of rice and other principal crops present in Cambodia.
Establish a culture collection at CARDI, with Australian plant pathologists assisting the local team to survey disease incidence and to collect, identify and lodge specimens into CARDI's new culture collection and herbarium.

Examine the pathogenicity of rice blast isolates already in northern and eastern Australia to current rice cultivars.
Collect isolates of P. grisea from northern and eastern Australia.
Undertake glasshouse and laboratory work to determine the genetic structure and the pathogenicity of the Australian isolates of P. grisea collected during the survey.

Evaluate the distribution, prevalence, severity and priority for future work of rice diseases occurring in Cambodia.
Aggregate all data generated by the disease surveys and prepare maps showing the distribution and prevalence of rice diseases in Cambodia and identify the most damaging diseases of rice occurring under Cambodian conditions

Develop, test and, if appropriate, promote some best-bet Integrated Disease Managements strategies for several major diseases including through trial of strategies such as crop rotation, using disease-free clean rice seeds, crop residue removal and variety mixing.