Answer in the bag
By Gio Braidotti
Graingrowers and handlers battling pesticide resistance in their storage silos may have a new option - large hermetically sealed plastic bags, called silo bags, that have become popular with overseas growers, particularly in South America.
Silo bags, which can store up to 300 tonnes, have been around for more than 10 years in Argentina, although their widespread adoption is a recent development. The largest manufacturer of silo bags in Argentina, IPESA, will manufacture more than 70,000 bags this year.
The bags are seamless, airtight when sealed and capable of stretching to form a smooth surface that makes it difficult for pests to burrow into the bag - or so the theory goes in countries that do not have kangaroos, mice plagues and cockatoos.
Because of growing interest in Australia, and the different conditions here, the GRDC is funding a two-year study by CSIRO"s Stored Grain Research Laboratory (SGRL) to assess the suitability of silo bags on Australian farms.
The bags, for example, have to be packed tight enough to force out air. This requires specialised packing equipment. The grain itself then turns residual oxygen into carbon dioxide, which asphyxiates insects and inhibits fungi growth.
Achieving a low-oxygen atmosphere is critical to successful insect and mould control, so poor sealing or punctures will cause the system to fail.
Despite this, some Australian growers are already exploring the use of silo bags, attracted by a number of perceived advantages, principally their potential cost-effectiveness compared to storage in fixed silos. They may also provide an effective way to control grain insects without the use of chemicals.
The SGRL study is being led by Len Caddick, who is keen to hear from growers who have used silo bags. Grower experience in Australia will be used to design a field trial in collaboration with the distributor of silo bags in Australia, Ian Metherall.
GRDC Research Code CSE00035
Region National, North, South, West