Effective grain storage is critical for farm businesses, both for optimum flexibility in terms of going to market and to ensure quality seed and feed grain for farm use.
According to a Kondinin Group study silos are by the most popular choice for grain storage, with this option representing around 81% of grain storage. Of this total, gas tight sealable silos sit at 53% and non-sealed silos at 28%.
Hygiene is of course essential in eliminating food sources and shelter that enable insects to breed on farm. This includes timely and thorough cleaning of grain handling equipment, grain storage equipment and surrounding areas.
Fenitrothion is commonly used to protect grain that will be stored longer term in unsealed silos or field bins, with the chemical commonly sprayed inside silos before adding grain. This product can also be applied using flat fan nozzles that spray into the auger, coating the grain as it is fed into storage. Dryacide can also be applied to grain as it is fed into the auger in the same way, with this chemical free product eliminating insects via dehydration. Dryacide can also be dusted on the inside of silos or other grain storage facilities, and as the product is chemical free, no withholding period applies to its use.
Fenitrothion has a withholding period of 90 days associated with its use if the product has been applied at the full rate for 9 months of protection.
If chemical resistance in insects is an issue, pre-mixed chemical combinations as well as other chemical options are also available for unsealed silos, with further useful information available at GRDC’s Stored Grain.
If you find evidence of insects in sealed silos containing cereals, pulses or oilseeds, aluminium phosphide tablets, bag-chains or blankets can provide knock down or fumigant protection. Aluminium phosphide products such as Quick Phos are only suitable for treating sealed storage structures that are gas tight, as the phosphine gas the chemical gives off to protect the grain simply escapes from unsealed storage. Full PPE must be worn when handling this chemical and a useful fumigation guide is available for it at GRDC’s Stored Grain.
For smaller sealed storage silos, the silo must be gas tight for an exposure period of 7-10 days (under cooler conditions work on at least 10 days). However, if the storage capacity is 300 tonne or more without recirculation, it must be gas tight for 20 days. Without the above periods of fumigation, the gas won’t achieve an effective kill to insects at all life stages. Lava and eggs will continue to develop, both damaging the grain and facilitating the development of resistance within insects.
Following the 7 – 10 day exposure period above, when using aluminium phosphide it is best to allow an aeration period of at least 5 days followed by a withholding period of 2 days. This results in a minimum safe total “lock up” timeframe associated with the product of 17 days.
If you do find suspicious insects in your grain, GRDC have provided the below useful visual tool to help you identify insects found, with further information on specific insects at Stored Grain. GRDC have also produced a useful Grain Storage Grow Note which includes the diagram below to help you with insect identification and a diversity of other information on grain storage.
For any grain storage questions, contact FarmCo’s Senior Agronomist Helen Lethlean on 1300 327 626.
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