Growers warned to beware of insects that may have infiltrated grain storage

A nasty surprise could be in store for growers when opening silos

Grain Storage
When stored grain insects are detected, fumigation of silos is the only control option and GRDC has some useful resources providing tips to optimise the effectiveness of treatments. PHOTO Chris Warrick

When stored grain insects are detected, fumigation of silos is the only control option and GRDC has some useful resources providing tips to optimise the effectiveness of treatments. PHOTO Chris Warrick

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Growers sowing winter crops may find some nasty surprises when opening their silos.

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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.

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."

Mr Warrick says spray-on protectants (not available for use in Western Australia) 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 says.

Control tips

When stored grain insects are detected, fumigation of silos is the only control option.

Mr Warrick says the only on-farm control options 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.

"All of these measures require gas-tight storage (AS2628) for reliable control results that avoid the development of resistance in insects," 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. - GRDC Grain Storage Extension Project manager Chris Warrick

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 and are part of a series of grain storage webinar recordings.

Grain storage tips

Meanwhile, Mr Warrick reminds growers and advisers of the top five practices for successful grain storage, as outlined below.

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.

5. Grain protectants (not available for use in WA): Used on specific parcels of grain like planting seed held on farm, or bulk grain where potential grain buyers have agreed to its use, grain protectant sprays provide another line of defence against storage pests. They are designed to deter insects, not kill them.

Further practical information and advice on best practice grain storage is available via the GRDC's comprehensive stored grain information hub at www.storedgrain.com.au.

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).

See also:

GRDC Research Code: PRB00001

More Information: Chris Warrick, Grain Storage Extension - national coordinator/southPhone 1800 933 845 (national)info@storedgrain.com.au

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