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Ontario Grain Farmer Magazine is the flagship publication of Grain Farmers of Ontario and a source of information for our province’s grain farmers. 

Safe storage


MANY YEARS THERE is carry in the market and a resulting economic advantage to storing grain. 


Since better returns are the goal, it is important to keep your wheat in top condition throughout the winter.  Insects and mould are the top threats to grain in storage and the main reasons why previously stored grain is rejected at the elevator. 

“The longer you keep grain, the harder it is to keep it safe,” says Helmut Spieser, Engineer with OMAFRA.  “It is important to prepare well in advance of harvest so equipment is mechanically sound and in good condition and bins are clean and free of any insects.”

Begin by treating the first and last loads into the bin with a product like Protect-It, which is specially treated diatomaceous earth.  This will control insects that try to move down into the grain from the top or up from the bottom. 

Once the grain is in storage, regular monitoring for insects and mould will help maintain the value of your crop.  Insects are drawn to good quality grain through their keen sense of smell and will enter bins as the grain is loaded or as the bin 
is aerated.

If insects are detected or suspected, it is important to deal with the problem immediately.  Once outside temperatures drop below freezing, fumigants cannot be used and nothing can be done to eliminate an insect problem until spring.  Elevators are likely to reject a load of grain if bugs are detected in order to protect their grain storage facility and the producer will have to pay for the truck’s round trip.

Although Indian meal moths are easy to identify through their spider web-like material at the top of the bin, most bugs do not like light and won’t be easily visible.  To test the bin it is best to use bug probe traps.  Since insects move away from the light, they tend to be at least a foot below the surface and will not be seen with the naked eye.  Leaving bug probe traps, made of 18 inch long perforated tubes with a double funnel at the bottom, close to the centre of the bin for a week, will provide a more accurate assessment of the problem.

If insects are detected, fumigation is required to control the problem before the grain is taken to an elevator, to avoid downgrading.  A trained and licensed professional must be hired to treat the grain with a fumigant that is sealed into the bin for a treatment period.  Even if treated, grain can still be sold to an elevator in the spring.

The other major threat to stored grain is moisture.  If temperatures within the bin are warmer than 5° C above the average outside temperature, moisture will be released which could start spoilage and eventually cause mould growth.  Heat and moisture can also be produced by high concentrations of insects that
will overwinter.

To avoid heat and moisture levels rising, grain must be aerated.  Aerating on a dry day will cool down the grain. In bins that are not aerated, warm air from the grain rises through the bin and cool air returns to the bottom through the centre.  Left unchecked, this air circulation will cause spoilage. OMAFRA has equilibrium moisture content charts to ensure aerating a bin will not add moisture. Farmers storing wheat must be  cognizant of outside relative humidity because small cereals are easily affected by such conditions and may take on some of that moisture. A good rule of thumb for wheat is to only aerate when the outside relative humidity is less than 70 percent.

“The best way to check for spoilage is with your nose,” says Spieser.  “Turn on the fan and stick your head into the top of the bin.”

If there is an off odour, pull out samples and investigate the problem further.  A local elevator will be able to run tests or contacting Helmut Spieser directly at OMAFRA to get an expert opinion will help narrow down   the problem. 

One solution may be to “turn” the grain by unloading the bin and putting it into another storage location.  As the grain is unloading, check for moisture and clumping.  Turning grain during the winter when the temperature has been below 10° C for over ten days can also “freeze out” any insects.  Elevators routinely turn bins to help maintain quality.

The key to maintaining grain quality through the winter is vigilance.  Check bins often for insects and temperature, aerate when the relative humidity is below 70 percent and if there is a problem, remember to act quickly.

Helmut Spieser, OMAFRA Engineer can be reached at 519-674-1618 or at For a full equilibrium moisture content charts from OMAFRA, go to their website at •


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