It is essential to fumigate the silo every time grain is added. Once the silo has been purchased, insect control is simple provided the silo is working correctly. The hatches must be sealed properly and the pressure relief valve filled with oil to the correct level. An annual check is essential. Fumigation of a poorly maintained silo does not control insects effectively as gas will be lost, insects will survive and they may produce future populations with a degree of phosphine resistance.
Proper fumigation is impossible in unsealed silos.
There may be an illusion of success when the adult insects are killed but once the gas has dissipated the next generation of insects will emerge. Existing unsealed silos may be modified and sealed but the cost varies depending on the design. Emergency fumigation Fumigation is most convenient and effective in a solid sealed structure. However, in the absence of such a grain store, a good fumigation can be carried out under a gas-proof tarpaulin. The aim of the procedure is to create a leak-proof envelope of plastic sheeting.