MANY common wheat varieties have this year recorded a change in their susceptibility ratings for leaf rust following the detection of an exotic strain of the disease in South Australia and Victoria last year.
Senior plant pathologist at the Victorian Department of Economic Development, Jobs, Transport and Resources (DEDJTR) Grant Hollaway said growers across South Australia, Victoria and NSW needed to be aware that the leaf rust ratings of many of their current varieties had changed. The majority of cultivars are now one rating more susceptible than before, however, several varieties, including Axe, Beaufort, Corack, Derrimut, Mace, SQP Revenue, and Wallup, are now two or more rating levels more susceptible.
“The new ratings are marked as provisional this year as we only have one season of data. It is likely however that this new leaf rust will be dominant in Victoria during the coming years so growers need to be more vigilant with leaf rust control,” he said.
“Growers must have a plan to manage rusts in susceptible varieties, as rust can quickly build up if suitable conditions occur.”
The Australian Cereal Rust Control Program (ACRCP) Consultative Committee’s minimum disease resistance standards recommend wheat varieties have no lower than a moderately susceptible (MS) level of resistance for leaf rust.
Dr Hollaway said growers needed to consult a current annual Cereal Variety Disease Guide to assess the susceptibility ratings of their varieties, and if possible, avoid growing susceptible varieties to reduce pressure from rust and the chance of yield loss.
“Resistant varieties make rust control easier, reduce inoculum carry-over from one season to the next, and decrease the chance of resistance breakdown,” he said. “To control rust, remove volunteer cereals by late-March, avoid rust susceptible varieties, use fungicides on seed or fertiliser at sowing, and watch crops with a view to timely fungicide application if needed.”
All current Cereal Variety Disease Guides are available online through the Rust Bust website http://rustbust.com.au/
