The strain of stripe rust first identified in Western Australia has proved to be even more aggressive and virulent than we feared and varieties thought to have moderate levels of resistance have succumbed to severe disease pressure.

Worse is the fact that this invasion has ruled many of our elite breeding lines out of contention for release. However, that's not the case with lines in the CSIRO's High Rainfall Zone (HRZ) program with plant breeder Dr Richard Richards describing "outstanding levels of resistance to stripe and leaf rusts".

The germplasm behind the lines in this program has come from NZ Crop and Food Research. They are derived from the northern hemisphere and New Zealand, subjected to growing conditions with much more disease pressure than we're used to experiencing here in Australia.

The New Zealand germplasm is routinely challenged with all of the principal rust pathogens through the Australian Cereal Rust Control Program, and trials in all states of Australia during the past season have thrown up a large number of lines showing almost total resistance to stripe rust.

Dr Richards isn't sure what genes are responsible for this high level of resistance but suspects that it may be a combination of several major genes and a number of minor genes. If that is the case then this level of resistance should be quite robust, as any new pathogen will need to overcome a combination of genes to break down the plant's resistance.

The HRZ wheat program is focused on producing quality milling wheat varieties for the expanding higher rainfall zone of the Australian wheat belt. Only white grain lines are under consideration, with the target of producing varieties that will make the Australian Hard (AH) segregation. Dr Richards concedes that it will require a high level of management to achieve the necessary protein content in the higher rainfall zone but insists that the varieties released in the program will have the necessary milling quality.

That's good news for the whole of our wheat industry because there should be no barrier to introducing the resistance found in the New Zealand germplasm to varieties suited to the more traditional growing areas.

The move to breed varieties especially suited for the High Rainfall Zone is particularly timely with the increasing value of livestock dictating a swing back to the traditional mixed farming approach and a renewed interest in the techniques of grazing grain crops. We're fortunate in Australia to have such a diversity of short, medium and long season wheat varieties that can be adapted to meet the changing circumstances of the industry.