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A nasty surprise could be in store when opening silos

Fumigation. Chris Warrick

Grain growers sowing this year’s winter crops may find some nasty surprises when opening their silos for the first time in a while.

If stored grain has not been monitored since harvest, it is possible that insects have infested storages, necessitating treatment.

Grains Research and Development Corporation (GRDC) Grain Storage Extension Project manager, Chris Warrick, says 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 says.

“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.”

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 says.

“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.

The webinar recordings can be found on the GRDC YouTube channel at and They are part of a series of grain storage webinar recordings,

Meanwhile, Mr Warrick reminds growers and advisers of the top four practices for successful grain storage:

1. Aeration cooling: Correctly designed and managed, it provides cool grain temperatures and uniform grain moisture conditions. Aeration reduces storage problems with moulds and insect pests, plus maintains a range of grain quality attributes relating to germination, pulse seed colour, oil quality and flour quality.

2. Hygiene: A high standard of storage facility hygiene is crucial in keeping background pest numbers to a minimum and reducing the risk of grain infestation.

3. Monitoring: To prevent nasty surprises, undertake monthly checking of grain in storage for insect pests (sieving/trapping) as well as checking grain quality and temperature. Keep monthly storage records, including any grain treatments applied.

4. Fumigation: In Australia, only fumigant gases (e.g. phosphine) are registered to deal with insect pest infestations in stored grain. To achieve effective fumigations, the storage/silo must be sealable – gas-tight (AS2628) to hold the gas concentration for the required time.

Further practical information and advice on best practice grain storage is available via the GRDC’s comprehensive stored grain information hub at

Mr Warrick also encourages growers and their advisers to contact their regional grain storage expert with any concerns or questions by calling the national hotline 1800 WEEVIL (1800 933 845).

Source: GRDC

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