Be Ready to Store Your Corn-Part I

Corn harvest has been underway for several days in south Georgia and some of it will be stored for later marketing or delivery.  It is wise to make sure you take precautions to avoid stored grain insects later if you are storing it on farm.  If you have been in your fields just prior to harvesting, you may have noticed some maize weevils.  This is a very destructive insect in stored corn. It is certainly possible that they have emerged from the very ear you found them on or from a nearby ear.  Often, the first fields planted with an early maturing hybrid, silk first and, when ears reach the proper conditions for hosting maize weevils, attract male maize weevils (possibly through volatile compounds released by the ear).  The male releases pheromones to attract females for mating and subsequent egg laying by the females. The life cycle is roughly 30 to 35 days under good conditions.  We have had good conditions for large maize weevil infestations to take place.

The following information was developed by Dr. Michael Toews, former UGA entomologist, Tifton on the proper management of stored grains .  This is the first part of a chapter on storing and protecting corn.



Dr. Michael Toews, UGA Entomologist and  Assistant Dean, CPES, Tifton, GA

The key to storing grains and other commodities on the farm is to make storage conditions unfavorable for the survival of stored grain insects and molds. Procedures described below are designed to reduce the initial number of insects in the bin, slow the development of any remaining insects, and apply corrective measures to reduce insect populations if necessary. Following these steps will also greatly reduce stored grain molds and associated mycotoxins.

Empty Bin Preparation

  • Clean storage bins thoroughly inside and out to eliminate starter colonies of insects. Remove any weeds, crop debris, or clutter around the facility to reduce insect and rodent activity. All grain residues from the previous year should be removed from inside the facility as soon as the old crop is
  • Seal any gaps or holes in the sides and roof of the bin using caulk or polyurethane foam. Check to make sure the bottom seal with the concrete is intact. Prevent water from flowing underneath the bin by applying plastic roof
  • · Apply an EPA-approved insecticide on the floors and sides of empty storage bins to eliminate insects hiding in cracks and crevices and to create a first line of defense against any insects that do find their way into the bin. Spray the outside of the bin to a height of 3 ft, and the surrounding concrete, gravel, or sod to a distance of 6-10 ft surrounding the bin. Insecticides shown in Table 1 are labeled for empty bin treatments.

Table 1.  Insecticides labelled for empty bin treatments






Tempo SC Ultra

0.25-0.5 fl oz/gal/1000 sq ft


Apply to all interior surfaces of storage bin and allow to dry before filling bins.


Centynal EC

0.25-1.5 fl oz/gal/1000 sq ft


Apply to wall and floor surfaces of grain bins and warehouses prior to storing or handling grain.


D-Fense SC

0.25-1.5 fl oz/gal/1000 sq ft


Use for exterior perimeter treatment only.


Suspend SC

0.25-1.5 floz/gal/1000 sq ft


Apply finished spray to equipment, wall and floor surfaces of grain bins and warehouses prior to storing or handling grain.

diatomaceous earth


Dust: 1 lb/1000 sq ft

Apply at least 2-3 days before filling bin. Use aeration fan or other air supply to apply dust.

diatomaceous earth

Dryacide 100

Dust: 1-3 lb/1000 sq ft Slurry: 1.5 lb/1.5 gal/100 sq ft

Apply as a dust with a hand or power duster or as a slurry spray.

diatomaceous earth


Dust: 0.6 lb/1000 sq ft Slurry: 1.5 lb/1.5 gal/100 sq ft

Apply 2 weeks before filling bins. Use a dust blower or bin fan to reach all surfaces, cracks and crevices. Apply slurry as a fine mist.

deltamethrin + chlorpyrifos methyl

Storcide II

1.8 fl oz/gal/1000 sq ft


Application can only be made from outside the bin using automated spray equipment.

pyriproxyfen Nyguard IGR Concentrate

0.8-2.4 tsp/gal/1500 sq ft 4-12 ml/gal/1500 sq ft


This product will not kill adults but will control immatures. May be mixed with an adulticide.


Diacon-D IGR

1.5 oz/1000 sq ft


This product will not kill adults, but will control immatures; applicators must wear a dust mask and protective gloves.


Diacon IGR

Fogging Treatment: 1 ml/1000 sq ft (0.2 tsp/1000 sq ft)

Pressure Spray: 2 ml/1000 sq ft (0.4 tsp/1000 sq ft)


Apply fogging treatment in water or oil in a cold aerosol generator. Diacon IGR is an insect- growth regulator that interferes with the development of insects. It will not kill adult insects. Apply as a pressure spray in low-pressure sprayer to all areas that may harbor insect pests.

  • Eventually, insects will build up on fines and broken kernels that accumulate under the perforated bin Bins with false floors should be fumigated if the grain debris cannot be removed. Cover with a plastic tarp (6 ml or thicker) to contain and hold the gas. Place the fumigant over the empty floor under the tarp. Fumigation should only be conducted by trained and licensed applicators. Read the label and the applicator’s manual. You will need to prepare a fumigation management plan before you fumigate.
  • Don’t forget to clean out harvesting and loading equipment such as combines, trucks and augers the end of each harvest If not clean, insects will reproduce in the small amounts of grain left in the equipment and then be conveyed into the new crop grain.

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