Is It Safe?

bins and wheat

By Harry Brook

Harvest is well under way and we finally have some decent harvest weather. Now is not the time to let down your guard. Be careful of that hard-won crop in the bin. You can’t relax just because it is in the bin.

First, make sure the bins you’re putting the grain in are thoroughly cleaned. Make sure there is no spoiled grain in the corners or hanging up on the sides. These are places where grain beetles can be found. If the bin is to be used to store cereals, a malathion spray can be used on the bin insides prior to putting new crop in. However, under NO conditions should malathion or any other insecticide be used inside bins to be used for oilseed or pulse storage.

There are two factors to consider when storing grain safely for an extended period. These are the temperature of the grain and the moisture content. Even when the grain is testing dry you must be careful, especially when grain temperature is hot. Hot grain is detected by grain beetles and will draw them to your bin. There is some moisture migration as harvested grain is put in the bin, even in dry grain. In the fall, moisture will migrate down the outside of the bin and circulate up to the middle of the bin, near the top. There are many storage charts showing safe moisture levels for various stored crops. They are a guideline but not a guarantee.

This makes it imperative that you cool off the grain once it is in the bin. Aeration fans are good at cooling the grain so you don’t attract grain beetles. In the case of grain beetles, it is far better to avoid the problem rather than having to deal with having to remove or kill them in stored grain.

If you have grain beetles, usually the first indication is when your crop is rejected at the grain elevator, upon delivery. It is expensive having to haul the load twice to make the delivery. Treatment options are limited.

To treat grain beetles you can fumigate, use diatomaceous earth or use cold temperatures. Each have their strengths and weaknesses. Fumigants, like phostoxin or gastoxin, can be used but you must have a valid Farmer Pesticide certificate with the fumigant endorsement to access the product. Furthermore, grain temperatures must be above 12˚ C to activate the fumigant.

Diatomaceous earth products like Protect-It© are best used as preventative measures. Even one live beetle in your grain can cause it to be rejected. They kill insects by physical action, the particles working into joints in the insects, causing lacerations and leading to the bugs drying out and dying.

Cold temperatures are also very useful to kill off beetles. However, you need to get the grain temperature down to at least -20˚C and keep it there for two weeks. Under that level of cold, the insects will desiccate and die.

At harvest, it is always a good idea to cool the grain down once it is in the bin. Keeping it in good conditions and monitoring it over the winter will ensure no unpleasant surprises when you deliver it.

Harry Brook is Flagstaff County’s Agricultural Fieldman. He can be reached via email at: or by phone at: 780-384-4138.