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12 Nov 2024. Paul McIntosh, Pulse Australia and WeedSmart.

A long time ago, our family farm inherited a conical based grain silo.

I really loved that silo as it meant much less shovelling for me on grain transporting days. Sure, it had a small leak in the roof and a few insects crawling around, which were annoying to me as the shovel person, however, I would have asked the family to buy the next-door property years before, just to get that silo.  

Roll on again over the decades and whilst conical based silos have gotten much bigger, extra safety conscious and more automated in their workings, there is one thing that has not changed and that is those damn grain insects.  

In our AMA Mungbean BMP agronomy courses, I generally ask a veteran storage expert, like my retired mate in Phil Burrill, to present a module on grain storage. Whilst Phil has now moved on, Alex or Chris certainly have plenty of passed down knowledge to offer good sensible advice on stopping insect infestation in silos.

First thing they all agree on is prevention is much better than cure. Second point is that airtight sealable storages are the only way to control weevil infested grain storages, so any fumigation of these pests can be done effectively and efficiently.

I recall Phil’s and the boys’ big point at field day presentations is maintaining hygiene in and around the silo complex. No piles, handfuls or clumps of loose grain sitting around in tins or near posts. And we are not just talking within 20 mts of this silo setup, we are talking many hundred of yards away as well, being clean and a grain free area. Our grain insects can fly very well from these even just handfuls of loose grain to your silo complex.    

My own most preferred method of grain insect control in bunkers or silos is aeration cooling.  By cooling the grain down to below 15 degrees C, our insect population cannot reproduce very well. Given that in a month many of our insect fiends can multiply 20 odd times, it is no wonder our grain storages can end up very messy and crawling with grain damaging insects when unchecked and in a warm atmosphere.

Why else do I like cooling method of stopping insects like Lesser Grain Borer, Weevils or Flour Beetles??

Well, the alternative options are fumigation with products like Spinosad, Deltamethrin, S- Methoprene or the last resort of Chlorpyrifos Methyl depending on your potential grain markets' acceptability levels of these older conventional insecticide products.

Of course, Phostoxin or Phosphine fumigation tablets were used massively in the 1960’s, 70’s and 80’s and we certainly used them very creatively in grain trucks on their way to the grain buyer.

Not any more are these dodgy practices even considered due to health and safety issues; to say nothing about the resistance levels our grain insects are developing to conventional chemistry.  One shining light from the late 1980’s is a product originally called Dryacide. This odourless non-poisonous powder is made up mostly of diatomaceous earth, which controls insects by adsorbing the natural oils and waxes from the crawling insects’ outer layers or skin, causing it to dehydrate and die. Not as easy to apply as an insecticide spray onto a conveyer belt of grain, however, on dry structural surfaces and grain below 12.5% moisture levels, it really does give grain growers and storage companies a lifeline, if all else fails in grain insect controls. Few more technical details to observe on this diatomaceous earth product, however a long-term option especially for future planting seed lots.

I believe we really are missing the mark in not having our grain storage units improved or updated, if possible, to acceptable safety standards and being airtight. Those storage insects are winning the war we have with them, so my long-time appreciation of conical based silos is now tempered with extra attachments like being airtight, a decent safety ladder and an automatic controller with the best sized aeration cooling system in the various grain types you may store.

Another dollar cost and time to be taken by growers and contractors in updating their grain handling systems, however I believe it is good long-term investment against insect pests that are winning the battle against us in trying to control them by our age-old methods.
 
Date claimer for Australian Crop Protection Forum at Highfields Cultural Centre on Wednesday 27 November with some excellent presenters.
 
That all folks.