Farmers preparing to plant this season's winter crop could be in a for a nasty surprise when they open their silos for the first time in months.
If stored grain has not been monitored since harvest, it is possible that insects have infested storages, necessitating treatment.
Grains Research and Development Corporation grain storage extension project manager Chris Warrick said his team often receives calls from growers in autumn after they have discovered insects while cleaning seed or at sowing.
"Sometimes this can be due to the fact that their silos don't have ladders, so they have been unable to monitor grain at the top of the silo where insects often begin multiplying," Mr Warrick said.
"The warmer and sometimes more humid air in the headspace of a silo is more conducive to insects reproducing so they are often found there first."
Mr Warrick said spray-on protectants applied at harvest time to grain set aside for planting seed is designed to prevent insects for six to nine months.
"Protectants are not registered for use on grain that is already infested with insects because they are designed to deter insects - not kill them. Each protectant chemistry can also only be applied to a parcel of grain once," he said.
When stored grain insects are detected, fumigation of silos is the only control option.
"The only on-farm control options we have to kill insects are phosphine, which can be applied by growers, ProFume, which can only be applied by a commercial fumigator, or establishing a controlled atmosphere with nitrogen or carbon dioxide," Mr Warrick said.
"All of these measures require gas-tight storage (AS2628) for reliable control results that avoid the development of resistance in insects."
To assist growers with treating stored grain, Mr Warrick has recorded two webinars on fumigating with phosphine and pressure testing silos.