Australian farmers grow $8 to $10 billion dollars of grain per year and now are holding an increasing amount of grain on-farm for extended periods before sale or consumption by livestock. Deregulation of the domestic grain market and increasing production of “non-traditional” grain crops as alternatives to cereal grains such as wheat, barley, and oats are key factors driving the move to greater on-farm storage.
Fumigating with phosphine in unsealed silos does not kill pests at all stages of their life cycle. Repeat fumigations in unsealed silos increases resistance levels and select for insects with a higher phosphine tolerance. In order to kill grain pests at all stages of their cycle (eggs, larvae, pupae, adult), phosphine gas concentration levels need to reach and remain at 300 parts per million (ppm) for seven days or 200ppm for 10 days. Trials show that these levels of gas concentration are impossible to achieve in silos that are not pressure tested and sealed gas-tight, so insects will not be killed at all life stages. The fumigation may appear successful when the adults die but the surviving eggs and pupae will continue to develop and reinfest the grain.
Technically, a farm silo is only truly sealed if it passes a five-minute half-life pressure test according to the new Australian Standards AS2628. Often silos are sold as sealed but are not gas-tight, rendering them unsuitable for fumigation.
APPLICATIONS TO SMALL SILOS (2 X 1000TN)
1. 2 x 1000 tonne silos unsealed ready to be sealed
2. Pressure cleaning the entire surface removing any dirt, grime and contaminates is essential.
4. Sealing the external floor to wall joint with a trowel able Global Flexible Filler over the joint. This is applied at a 10 deg slope away from the silo wall to stop water ponding at this location and can withstand the excessive movement.
5. The roof to wall section which is called the eave is generally the hardest area to seal. The void at the eave can vary pending on design and manufacture and needs to be very flexible as the roof and wall metal thickness are different which move at different rates. This area is sealed using a combination of polyurethane mastic’s and Glo-Mastic.
10. Sealing project completed in 9 days to AS2628 . 2 x 1000 tonne silos ready to be fumigated as this process can be done full or empty.