WHEAT growers still using varieties rated as susceptible or very susceptible must put a rust management plan in place.
Australian Cereal Rust Control Program Consultative Committee chairman Grant Hollaway said S and VS varieties should be avoided when growers worked out their cropping intentions for the new season. But if that was not possible, a fungicide program was essential to manage disease threats.
"Using fungicides applied to seed or fertiliser at sowing combined with subsequent foliar fungicides if required can provide effective rust management," he said.
"Using fungicides to keep rust levels low will also reduce the chances of the rust changing and overcoming effective resistance genes."
There is a big threat of rust outbreaks in wheat crops this coming season due to a high spore load in last year's stubbles. The disease level will depend on rainfall over summer.
Dr Hollaway said other factors affecting rust damage included the strain of rust present in a region and timing of the disease outbreak.
He said growing S and VS varieties increased inoculum levels, placing pressure on other less susceptible varieties being used in the region.
"It only takes one S and VS crop with no control in a district for a rust outbreak to occur," Dr Hollaway said.
"Growers are encouraged to pick up the phone and ring their neighbours to let them know of any rust outbreaks so they can put their management plan in place - it's that simple."
Dr Hollaway encouraged growers to use cereal disease guides to select wheat varieties with the highest level of rust resistance, but also taking into account other agronomic traits.
He said that, by selecting varieties with appropriate levels of resistance, it was possible to:
REDUCE the build-up of rust populations which caused regional epidemics.
DECREASE pressure from existing rust strains.
LOWER the chance of current strains mutating into more virulent ones.
REDUCE production costs associated with chemical use.
REDUCE the risk of significant yield and quality loss from rust outbreaks.
Dr Hollaway said that, even if growers selected partially resistant varieties for sowing in autumn, they might need to also use fungicides.
Growers should be aware that all chemicals had maximum residue limits which restricted the amount of active ingredient that could be applied to a single crop.
