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How do I prevent insect infestations in my stored organic grains?


Many organic producers use diatomaceous earth, commonly called DE, to control insect infes­tations in organic grain storage. This fossilized remains of an ancient hard shell algae is used in many food-grade products, including as a filtra­tion aid for liquids and in toothpaste. The fine powder kills a wide variety of insects or larvae by absorbing lipids from their exoskeletons’ waxy outer layer, causing them to dehydrate. Due to these characteristics, anyone handling this prod­uct should use a tight-fitting filter or respirator over their nose and mouth and goggles over their eyes to prevent health problems. Long sleeves, pants and gloves would be a good idea, too.

Typically, DE is scattered on the floor of the grain bin and periodically added to the grain as it is being loaded into the bin. Add 1 cup of DE to every couple of bush­els or so of grain for good coverage. If you have a perforated floor in your bin with a fan, you can have the fan running on low as you load the bin to incorporate the DE into the first few feet. It is also a good idea to lift up the floor and clean underneath before loading it with this year’s crop.

If you can, run the grain through a spiral screen air cleaner before storage (pictured below). This will lessen the chaff, screenings, and insect load in your stored grain. It also dries grain bet­ter for higher quality long-term storage. Running your grain through the same cleaner before load­ing to your buyer would also be appreciated, since DE can be abrasive to their cleaning equipment. Shipping clean grain also means there will be less dockage from your payment due to screen­ings and foreign matter.

Make sure you leave head space at the top of the bin to allow for moisture to escape. If you are concerned about vomitoxin or other issues, test before you put it in the bin. The grain will not improve in quality when in storage, so knowing what you have at the start will help you make decisions on where to sell your crop and how long to store it.

Another resource with recommendations on managing grain after harvest is available from Iowa State University at this link .

Posted: Aug 2014
Answer By: Harriet Behar