Summary

Identification of the causal agent of the red leaf disease
This will be conducted by employing serological (ELISA) and molecular (reverse transcription PCR) techniques with the advantages of sensitivity, reliability, rapid turn around and economic efficiency relative to standard biological protocols. Diseased plant specimens will be established in the greenhouse as positive control material.

Epidemiology
Studies will be undertaken to test for mechanical and/or vector transmission of the disease. Information on virus-vector relationship such as persistence of the virus, acquisition threshold, availability threshold, latent period threshold and transmission of the disease via seed will be obtained. Establishing the host range of the causal virus and vector is vital, as this will provide necessary information for prediction of disease outbreaks.

Screening of the subterranean clover cultivars for resistance to the disease
Cultivars representing all three sub species of T. subterraneum namely subterraneum, brachycalycinum and yanninicum will be tested for their reaction to this disease. This will be conducted by sowing the cultivars in replicated plots and then inoculating them mechanically or with infected vectors. The effect of the disease on seed production of the cultivars will be determined.

Program

Pasture Seeds

Research Organisation

Minister for Primary Industries and Regional Development acting through the South Australian Research and Development Institute

Objective Summary

To improve seed production technologies for maximizing yield, quality and processing efficiency by:
1) Developing molecular diagnostic tools for identification of subterranean clover red leaf virus (SCRLV) and other viruses known to infect subterranean clover. (Thereby providing a service to growers and industry and hence supporting both production and domestic and export sales of quality, certified sub clover seeds).
2) Establishing whether SCRLV is associated with the sub clover red leaf disease currently prevalent in seed production stands.
3) Assessing the incidence and severity of SCRLV in seed production regions.
4) Determining the level of resistance to SCRLV in varieties of sub clover and selected genebank accessions.
5) Determine the disease cycle leading to infection of the stands and develop integrated disease management (IDM) protocols.
6) Compile the results from the project in a report for RIRDC to publish.