It has been a soft finishing season for Western Australia and while growers are busy harvesting and preparing for their summer holidays, most will also be planning and initiating their cereal rust defence for next year.

Cool and damp conditions from October to early November aided the survival of rust inoculum, increasing the potential risk of a 2006 rust infection.

The presence of late rust infection can provide opportunities for green-bridge carryover of rust, especially if summer and autumn rainfall is received.

For these reasons, growers need to think very carefully about their 2006 variety selections.

Heavy inoculum loads resulting from susceptible varieties will make disease control much harder because fungicides will be less effective against heavy infections.

High inoculum also makes control more expensive because more sprays are required and it also increases the risk of disease mutation, putting existing disease resistance genes at risk of breakdown.

To help ensure next year is a good year, Grains Research and Development Corporation (GRDC) supported Plant Pathologist at the Department of Agriculture, Dr Rob Loughman, has some advice for rowers.

He advised growers to minimise or avoid planting very susceptible varieties such as Westonia or H45.

Where very susceptible varieties remain in use in 2006, pro-active preventative strategies to manage rust risk should be implemented.

Dr Loughman recommended that growers retaining very susceptible varieties should plan now to use long acting seed dressing, or in-furrow fungicides, to reduce rust risk in 2006.

He added that a majority of the initial rust reports this year were from susceptible varieties, which hadn't undergone early fungicide protection.

However, fungicides will not prevent these varieties carrying rust over summer if green-bridge conditions develop.

Dr Loughman concluded by saying that, for this reason, paddocks where very susceptible varieties were grown in 2005 should be actively managed over summer with herbicide or grazing to remove volunteers.

Those growers who remove susceptible varieties from their program are actively reducing the risk of in-season rust epidemics and between-season disease carry-over. 

They are also contributing to the longevity of our valuable rust resistance genes, which remain the platform on which we need to build our fungicide and other disease control strategies.

Regular rust risk updates, including Western Australia risk maps, are available from the 'Plant Disease Forecast 2006' on the Department of Agriculture's website www.agric.wa.gov.au