Application of sealing technology to permanent grain storage in Australia.

Expanding grain production in Australia in the mid 20 century combined with a low population density provided millions of tonnes of surplus grain that could be sold on the world market but insect infestation was a problem. Investment in large-scale grain handling systems was needed and millions of tonnes capacity of grain storage was constructed, much of it as horizontal structures. The advent of chemical protectants in the 1960’s provided a solution for controlling grain insect pests and enabled the export of insect-free grain. However, escalating insecticide resistance proved a challenge and a more effective control using fumigants in sealed structures was investigated. Identification of appropriate acrylic sealant systems allowed existing structures (formerly considered un-sealable) to be retro sealed. Information provided by research organisations on sealing techniques and the commercialisation of the sealing process provided the impetus for the central grain handling authorities to commit to extensive retro sealing of existing storages. At the farm level, innovation by manufacturers of silos provided sealable structures to ensure an effective fumigation could be performed on farm grain stocks. This reduced the background level of insects on grain growing properties that had the potential to enter the central storage system. This paper discusses the techniques employed on-farm, and in the central grain storage system over the last 20 years to create storage structures capable of containing fumigant gases at lethal levels to ensure effective control of insect populations.