GRAINGROWERS wanting to win the war against weevils should properly clean on-farm silos before filling with freshly harvested grain. Further, they should remove any spilled grain from last season and any grain near hay sheds and silos. And they should take necessary safety precautions as they work in the silo.
That's the word from Chris Newman, WA state coordinator of the GRDC-sponsored Phosphine Awareness Campaign. "When you've tinished seeding orfeeding and the silo is supposedly empty, it still contains enough residues to keep a small army of insects alive until the next harvest. Flat-floored silos are the worst culprits and retain plenty of residues to harbour insects."
Mr Newman, of the Western Australian Department of Agriculture, reminded growers not to forget the silo boot and to remove residues from around the silo pad, as these too could harbour weevils.
Growers should check with their state phosphine project coordinator for appropriate phosphine fumigation strategies.
"If, after fumigation, you climb into the silo to shovel out the last of the grain, you must wear a half-face respirator, fitted with a new organic/inorganic cartridge, plus proper eye protection and overalls," Mr Newman stressed. The powder remaining from the tablets of phosphine still contained dangerous levels of phosphine, which was activated only in the presence of moisture.
"As you shovel, you' re breathing in this toxic dust and the moisture in your mouth and nose will release the phosphine. Also, before entering the silo, you must ventilate it thoroughly by having all doors and lids open for at least three days," Mr Newman said. To ensure the fumigation is successful, first check all seals on the silo to determine whether they can hold phosphine gas for long enough to eliminate all stages of the insects.
And remember ...
Using phosphine in unsealed structures is ineffective, as the gas is quickly lost and surviving insects could become resistant, causing worse control problems the next year. Growers should refer to the instructions on the yellow label attached to the side of their silos for the annual pressure test, using a compressor. A tray should be used to hold the phosphine tablets and prevent residue entering the grain. Phosphine bag chains could also be used.
For more information about phosphine, contact the project coordinator in your state or the project supervisor, Dr Graham White of DPI Queensland, on 074688 1035.
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