Managing stored grain to minimize storage losses

In addition to cleaning the bin, always keep the surrounding areas clean. This includes the outside area around the bin, beneath the floor and inside the ducts.

Debris and grain spills outside the bin encourage rodents and insects, which can then move in through openings. Prevent weeds from growing around bin areas, as these are ideal sites for pests to hide.

Inside the bin, sweep or vacuum grain dust and old grain from floors, walls and ceilings, which provide hiding places for stored grain insects. Here’s a common rule-of-thumb: If you can tell what has previously been in the bin, it’s not clean.

If you cannot easily remove the bin’s perforated floor and had insect infestations last season, consider hiring a professional pest control operator to fumigate the empty bin before filling it with new grain.  

Roof leaks commonly lead to columns of spoiled grain. Check for these leaks by looking for light coming into the bin. Moisture coming into the bin through the seal between the bin and concrete will cause spoilage around the perimeter of the bin at the base.

Check the seal because sealants do deteriorate. Water will run away from the seal at the base of the bin wall if the concrete is sloped away from the bin. Also check the seals around the doors and hatches.

After cleaning and repairing, use a residual bin spray to treat the insect surfaces of the bins at least two weeks prior to filling (see Table 1).

It’s better to treat during the warmer months when insects are active. If you applied treatments more than three months earlier, apply an additional treatment two to three weeks before placing new grain in the bin.

When using residual bin sprays, clean, sweep and spray all bins before harvest. Do not add grain to a treated bin for at least 24 hours or until the walls have thoroughly dried.

Insecticides are registered for use in Minnesota to protect stored grain from insects, and were updated in April 2018. Active ingredient(s) are noted in parentheses

Sources: Minnesota Department of Agriculture Product Registration list, CDMS label search, Greenbook. Information subject to change. Read insecticide label for final authority.

Run grain harvested with a clean and properly adjusted combine through a grain cleaner to further remove the fine materials which insects can feed on. You can also run grain with many broken kernels through a cleaner, but this will lead to additional weight loss.

Clean, whole grain helps manage insects, but it’s also important for properly aerating the grain mass during drying and storage. If fine materials aren’t present, air drawn into the grain from outside the bin will move more uniformly through the mass.

A grain distributor uniformly spreads fine material across the grain mass, and is extremely helpful in preventing fine material aggregations.

If you don’t use a distributor, the fine material will concentrate in a column at the center of the grain mass. Because this column is more dense, air will move around it through the less-dense grain mass, allowing moisture to build up in the center of the bin. Moisture buildup is the first step in grain quality deterioration.

Loading refers to creating a grain mass with several basic properties that ease handling and lead to long life.

The grain mass should be clean and dry, uniform without foreign material and stored in an aerated weatherproof structure. In addition, if you’ll be holding grain in storage for a year or more, use a grain protectant (see Table 2, in the “Protecting the grain” section below) to protect against stored grain insects.

Specific practices that help approach the ideal grain mass include:

• Use slow drying methods to limit kernel damage.

• Limit the number of times grain must be handled.

• Operate augers and elevators at capacity and at the slowest possible speeds.

• Store grain in aerated structures.

If you’re going to apply insecticide protectants to the grain, treat the grain stream just before it reaches final storage (Tables 2 and 3). Grain that’s treated and then transferred long distances through numerous grain handling systems – such as pneumatic systems, belt augers, conveyors, spouts, legs, etc. – before storage will have less insecticide residue when the grain is finally loaded into the bin.

It’s very important to note that, when grain drying is necessary, apply an insecticide protectant after the grain goes through the drier and has cooled. Commercial grain dryers generate enough heat to rapidly degrade insecticides applied to grain prior to the drying process.

Use grain protectants as you auger grain into the bin. Insecticides are registered for use in Minnesota to protect stored grain from insects, and were updated in April 2018.

Sources: Minnesota Department of Agriculture Product Registration list, CDMS label search, Greenbook. Information subject to change. Read insecticide label for final authority.

This is an alternative to treating the entire grain mass. Insecticides are registered for use in Minnesota to protect stored grain from insects, and were updated in April 2018.

Sources: Minnesota Department of Agriculture Product Registration list, CDMS label search, Greenbook. Information subject to change. Read insecticide label for final authority.

Immediately after filling the bin and leveling the grain, apply a surface treatment (“top dressing”) of an approved grain protectant (Table 4). The surface treatment helps control insects that enter the grain through roof openings.

Surface treatments alone generally will not keep the grain insect-free, but they can reduce insect populations during the storage period. Surface treatments are effective if the following limitations are understood:

• Surface treatment will not control an established insect infestation already in stored grain.

• The surface treatment should not be disturbed, since it provides the protective barrier against insect infestations.

Apply insecticide to surface after grain is binned. Note: To ensure maximum control, remove all surface crusting and webbing prior to treatment. Insecticides are registered for use in Minnesota to protect stored grain from insects, and were updated in April 2018.

Sources: Minnesota Department of Agriculture Product Registration list, CDMS label search, Greenbook. Information subject to change. Read insecticide label for final authority.

Keep grain temperature less than 50 degrees at all times of the year. In the upper Midwest, aerate to cool grain to 20 to 30 degrees for winter storage.

You should be able to cool grain to temperatures below 50 degrees Fahrenheit by gradually cooling the grain throughout the fall. Insect activity reduces at this temperature.

Minnesota temperatures allow you to achieve a target stored grain temperature of 25 degrees in the winter. At this temperature, insect activity ceases and some mortality will occur for a number of stored insect pests.

Make sure to cool and uniformly dry the grain mass. Move the cooling front completely through and out of the grain mass and maintain low grain temperatures as long as possible during storage.

It’s not necessary to rewarm dry grain with fans during the spring and summer.

Table 5 summarizes the recommended moisture levels for various grains for short- and long-term storage.

More guidelines: Managing stored grain with aeration

Inspect stored grain every seven to 14 days when either outdoor or grain temperatures are greater than about 50 degrees Fahrenheit. For grain in good condition that’s been cooled to less than 30 degrees, you can increase the inspection interval to once every three to four weeks during cold weather.

Check for insects by screening them from the grain, examining kernels for damage, looking for webbing, detecting off-odors or monitoring grain temperatures. Insect infestations can raise grain temperatures to as high as 110 degrees Fahrenheit.

During the summer and fall, insect infestations are usually near the grain’s surface. During cold weather, stored grain insects congregate at the center and lower portions of the grain mass and may escape detection until extensive heating has developed.

The following tables show the relationship between grain moisture, storage temperature and storage time:

• Approximate allowable storage time for cereal grains

• Approximate allowable storage time for soybeans