Storing Your Corn-Part 2

Weather has been good for getting corn out of the field and some of you may be planning to store your grain.  Last week, I put together part one “Be Ready to Store Your Corn-Part 1”. This is the second part of a chapter on storing and protecting corn by Dr. Michael Toews, former UGA entomologist, Tifton on the proper management of stored grains .  I encourage you to read part 1 if you haven’t before reading this blog entry. It is a great primer to storing any corn.  We have a very good crop and with prices down, we don’t need to lose any quality if possible. Now for part 2.

Part 2:  Once your bins are cleaned and treated (see part 1) and the areas around all your bins are clean and treated then you should be ready to begin proper storage of your new crop. It is most important to store only clean and dry grain.

  • Store the grain at the appropriate moisture content. Insects and molds require moisture to survive. A general guide to proper moisture content is shown in Table 2.

Table 2.  Recommended maximum moisture content for grain in aerated storage bins

Expected Storage Time
Commodity 6 Months 6-12 months >12 months
Corn and grain sorghum 14% 13% 12%
Soybeans 13% 12% 11%
Small grains 12% 11% 10%
Edible beans 14% 12% 10%
  • Store clean grain. Removing or equally dispersing fine particles and other foreign material will increase aeration efficiency and the effectiveness of grain protectants and fumigants. The following steps contribute to clean grain: effective in-season weed control, properly adjusted combines, use of a grain pre-cleaner, coring the bin after it has been loaded, and use of a mechanical spreader at the top of the
  • Once the grain is in the bin, make sure the surface is level and the bin is not over filled. Leave a few feet of the straight side of the bin as air space to facilitate aeration and monitoring. If your bin does not have a spreader, unloading one or more loads of grain will help level the central peak as well as uniformly distribute fine particles that otherwise accumulate in the center of the bin.

Application of Grain Protectants

  • Growers who will be storing for more than 6 months should strongly consider application of a grain protectant (Table 3). Apply an approved grain protectant directly to the moving grain stream at the bottom of the bucket elevator or auger so the material has an opportunity to contact as many kernels as possible as the grain is moved.
  • UGA Extension recommends that grain be conditioned with a cooling cycle or similar procedure before applying the However, recent data suggests that deltamethrin (Centynal EC or Defense SC) and spinosad (Sensat) are heat stable up to 200° F, while s-methoprene (Diacon IGR) and pirimiphos-methyl (Actellic 5E) were degraded by high heat.
  • Position the insecticide nozzle as close to the auger flighting as possible to minimize insecticide drift.

Table 3.  Insecticides labelled for direct application to grain as a grain protectant






Actellic 5E

8.6-11.5 fl oz (corn)

8.6-11.5 fl oz (grain sorghum)

1B Labeled for use on shelled corn, popcorn and grain sorghum only. DO NOT use if grain has been previously treated with Actellic or if Actellic will be used as a topdress treatment.

Centynal EC

8.5 fl oz (corn)

9.1 fl oz (wheat)

4.9 fl oz (oats)

8.5 fl oz (grain sorghum)

8.5 fl oz (rye)

3A Labeled for use on barley, corn, oats, popcorn, rice rye, grain sorghum, and wheat.

D-Fense SC

8.5 fl oz (corn)

9.1 fl oz (wheat)

8.5 fl oz (oats)

8.5 fl oz (grain sorghum)

8.5 fl oz (rye)

3A Labeled for use on barley, corn, oats, popcorn, rice, rye, grain sorghum, and wheat.

Diacon IGR

1.8-7 fl oz (corn)

1.8-7 fl oz (wheat)

1-4 fl oz (peanuts)

1-4 fl oz (oats)

1.8-7 fl oz (grain sorghum)

7A Labeled for use on wheat, corn, grain sorghum, barley, rice, oats, peanuts, and sunflower. Will not control weevils. Diacon IGR is an insect-growth regulator that interferes with the development of insects; it will not kill adult insects. Treat existing insect populations with an adulticide before or at the same time as applying Diacon IGR. Apply only once to grain of known treatment history. Use highest rates for maximum residual. Lowest rate provides shorter residual.

Diacon-D IGR

8-10 lb 7A Labeled for use on cereal grains, corn, sunflower, canola, legumes, popcorn, wheat, spices, grain sorghum, rice, cocoa, peanuts, oats and millet. Will not control weevils. Diacon-D IGR is an insect-growth regulator that interferes with the development of insects. It will not kill adult insects. Treat existing insect populations with adulticide before or at the same time as applying Diacon-D IGR. Apply only once to grain of known treatment history.
Deltamethrin +

s-methoprene Diacon IGR PLUS

9-18 fl oz (corn)

9.6-19.2 fl oz (wheat)

5.2-10.3 fl oz (oats)

8-16 fl oz (grain sorghum)

9-18 fl oz (rye)

3A+7A Labeled for use on barley, corn, oats, popcorn, rice, rye, sorghum and wheat.
diatomaceous earth

Dryacide 100

1-2 lb/ton Thoroughly mix with grain. For use on grains, soybeans, peanuts, popcorn, and others (see label). Diatomaceous earth products are less effective when used on grain with increased moisture content and under humid conditions; diatomaceous earth is known to decrease test weight and grain flowability.
diatomaceous earth


1 lb/ton

1-2 lb/ton (if infested)

Apply uniformly as a dust on grains, soybeans, peanuts, popcorn, and others (see label). See note above.
diatomaceous earth


18 lb (wheat, beans, peas)

9.6 lb (oats)

16.8 lb (rye)

Uniformly treat grain as it is loaded into bin. For use on grains, soybeans, peanuts, popcorn, and others (see label). See note above.


9.8 fl oz (corn)

10.5 fl oz (wheat)

5.9 fl oz (oats)

9.8 fl oz (grain sorghum)

5 Labeled for use on barley, bird seed, corn, foxtail millet, pearl millet, proso millet, oats, sorghum, triticale and wheat.
deltamethrin + chlorpyrifos-methyl

Storcide II

12.4 fl oz (wheat)

11.6 fl oz (grain sorghum)

6.6 fl oz (oats)

1B+3A Dilute with water or an FDA-approved food grade mineral oil or soybean oil. For use on wheat, barley, oats, rice, and grain sorghum.

Insect Management

  • Stored grain insects thrive in warm grain. The hotter it is, the faster insects feed, grow and reproduce. Conversely, stored grain insects quit developing when temperatures are below 60°F. Grain temperatures are optimally managed using thermostatically controlled aeration that enables the fans to operate only when the outside air temperature is cooler than the set point. Once the grain reaches the set point temperature, set the thermostat to the next cooler set point. Growers in the deep south should use temperature set points of 75°F, 65°F and 45°F, whereas growers north of a line between Columbus and Savannah should use 70°F, 60°F and 40°F. It is important not to let the grain freeze as this will result in “sweating” when the grain warms in the spring. Temperature cables, moisture sensor cables, and automated aeration controllers make aeration more efficient.
  • Initiate a systematic and thorough insect-monitoring system. Check the grain every 21 days from spring to fall and monthly in winter for the presence of insects. Five trier samples or probe traps should be sufficient on each sampling
  • If you begin to find insects such as weevils or lesser grain borers, sell the grain, move the grain to another bin and apply a grain protectant as you move it, or fumigate the grain (Table 4). Read the fumigant label and applicator guide carefully. Follow the instructions provided because the label is the Aluminum phosphide is the most frequently used on-farm fumigant. It requires the preparation of a fumigation management plan before any fumigant is applied. If there are leaks in the bin, the fumigant cannot be held long enough to kill the insects. Seal all openings before loading the bin, including the aeration fan, top vents, eaves, roof entry door and side entry door. Many fumigation attempts fail because the gas is not held long enough. Read the fumigant label to determine how long it will take the fumigant to reach a lethal level. It may take a day or two to reach the desired concentration; therefore, leave the bin sealed for the recommended length of time. A closed-loop fumigation can make fumigation more efficient and safe. In this method, fumigant is circulated in a pipe outside the bin from the top to the bottom and then drawn up through the grain to the surface:

Table 4. Grain Fumigants

Product Rate Remarks
aluminum phosphide pellets Weevil-Cide 60% pellets, Phosfume2 60% pellets, or Phostoxin 60% pellets Farm bins:

350-725 pellets/1000 cu ft

All formulations of aluminum phosphide now require you to prepare a written fumigation management plan.


PHOSPHIDE. Many on-farm fumigations fail because the bin is not sealed adequately. Seal bin as tightly as possible. Use higher doses for older, less well-sealed grain bins.


Dosage must be based on the capacity of the grain bin, not on the amount of grain in storage, unless the surface of the grain is tarped after aluminum phosphide application. If grain is tarped, dose can be based on the volume of the grain in storage. All formulations of aluminum phosphide are RESTRICTED USE pesticides. Dosage rate varies with the site. See the Applicators Manual that is part of the label.

aluminum phosphide tablets* Weevil-Cide 60% tablets, Phosfume2 60% tablets, or Phostoxin 60% tablets Farm bins:

70-145 tablets/1000 cu ft

Phostoxin Tablet Prepac (33 tablets)** See label Phostoxin tablet prepack is a RESTRICTED USE pesticide.
cylinderized phosphine + carbon dioxide gas

Eco2fume Fumigant Gas

See label Eco2Fume is a mixture of phosphine and carbon dioxide gases that are packaged in compressed gas cylinders; it is labeled for use by certified applicators only. It is a restricted use insecticide and requires specialized training and equipment. Eco2Fume is a RESTRICTED USE pesticide.
pure phosphine gas


See label Vaporph3os is a RESTRICTED USE pesticide and requires specialized training and equipment for application. It is pure phosphine gas that is blended with carbon dioxide on site.
cylinderized sulfuryl fluoride


See Label To be blended with carbon dioxide or forced air on site. Contact Cytec Industries for more details (905-374-5899). Profume is a RESTRICTED USE insecticide. See label and applicators manual.


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