Organisms such as insects, fungi and bacteria exist in stored grain and become active under warm moist conditions.

Insects in grain

Insects are present in the environment and will enter the new grain as it is being loaded into the silo. Fumigation at harvest in a tested sealed silo is essential to prevent a population explosion later in the year. Aeration in unsealed silos will keep grain cool and insect populations low.

Options to protect grain

Options to control stored grain insects are limited in WA, chemicals other than malathion are banned. Fumigation is the main alternative and Dryacide® for unsealed storage and organic storage. Aeration cools grain providing advantages in harvest management, long term high moisture storage and retains grain quality and germinability.

Fumigation procedure

Phosphine is the main insect control on farms and in the export grain pathway. Resistance to phosphine is widespread and increasing. Correct fumigation means no survivors.

Only a sealed structure will hold the gas long enough to achieve complete elimination of insects in a grain bulk.

Preparation for harvest

Clean out and spray out all grain handling equipment and grain stores at least three weeks before harvest. Check sealable silos by pressure testing and repair as necessary. Remove weeds rocks and rubbish from the grain storage area.

Storage management at harvest

Store only grain below 12% moisture content in sealed silos or up to 15% in aerated silos. Do not put phosphine tablets up the auger, place them on a tray in the headspace when the top lid is closed.

Run aeration fans for 48 hours after loading the grain to lower the temperature to 20°C or below

Storage management after harvest

Remove spilt grain and keep the site free of rubbish that can harbour grain insects. Check grain in the headspace monthly. Pitfall traps give an early warning of insects in the grain. Leave silo sealed until outloading. Run aeration fans manually for a few hours a week to maintain a low temperature.