Georgia Corn: Protecting Stored Grain

Grain bin storage. Photo: @Debra L Ferguson

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. The following steps 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 shipped.
  • 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 roofcement.
  • 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 labelled for empty bin treatments.

Table 1. Insecticides labelled for empty bin treatments

Insecticide Rate MOA Remarks
beta-cyfluthrinTempo SC Ultra 0.25-0.5 floz/gal/1000 sq ft 3A Apply to all interior surfaces of storage bin and allow to dry before filling bins.
deltamethrinCentynal EC 0.25-1.5 floz/gal/1000 sq ft 3A Apply to wall and floor surfaces of grain bins and warehouses prior to storing or handling grain.
deltamethrinD-Fense SC 0.25-1.5 floz/gal/1000 sq ft 3A Use for exterior perimeter treatment only.
deltamethrinSuspend SC 0.25-1.5floz/gal/1000 sq

ft

3A Apply finished spray to equipment, wall and floor surfaces of grain bins and warehouses prior to storing or handlinggrain.
diatomaceousearthInsecto 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 earthDryacide 100 Dust: 1-3 lb/1000 sq ft Slurry: 1.5 lb/1.5 gal/100 sqft Apply as a dust with a hand or power duster or as a slurry spray.
diatomaceous earthProtect-It Dust: 0.6 lb/1000 sq ft Slurry: 1.5 lb/1.5 gal/100 sqft Apply 2 weeks before filling bins. Use a dust blower or bin fan to reach all surfaces, cracks and crevices. Apply slurry as a finemist.

 

deltamethrin + chlorpyrifos methylStorcide II 1.8 fl oz/gal/1000 sq ft 1B+3A Application can only be made from outside the bin using automated spray equipment.
pyriproxyfenNyguard IGR Concentrate 0.8-2.4tsp/gal/1500 sq ft 4-12 ml/gal/1500

sq ft

7C This product will not kill adults but will control immatures. May be mixed with an adulticide.
s-methopreneDiacon-D IGR 1.5 oz/1000 sq ft 7A This product will not kill adults, but will controlimmatures; applicators must wear a dust mask and protective gloves.
s-methopreneDiacon 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) 7A Apply fogging treatment in water or oil in acold 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 mayharbor insect pests.
  • Eventually, insects will build up on fines and broken kernels that accumulate under the perforated bin floor. Bins with false floors should be fumigated if the grain debris cannot be removed. Cover with 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 season. 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.

It is important to remember to store corn at 12% moisture for long term storage (12 months)

Update on Stored Grain Protectants:

Empty Bin Treatments

Centynal EC. This is a good product for treating empty bins and elevator boots. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical.

Defense SC (labeled for empty bin use only). This is a good product for treating empty bins and elevator boots, but is not labeled for application directly to grain. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical.

Suspend SC. This is a good product for treating empty bins and elevator boots. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical.

Tempo SC (labeled for empty bin use only). Tempo is a good product for treating empty bins and elevator boots, but is not labeled for application directly to grain.

Direct Application to Shelled Corn and Grain Sorghum:

Actellic 5E. This product has long been the standard for use on corn and grain sorghum. A full rate will provide protection from weevils for 9-12 months. Reducing the rate will decrease the longevity of the protection. UGA data suggest that Actellic is susceptible to heat degradation in the drier when grain temperatures exceed 120 F.

Centynal EC. Centynal EC is a new formulation that will provide 3 to 6 months of protection from weevils. This material is heat stable in the drier (tested up to 150 F).

Diacon IGR. Diacon IGR is an insect growth regulator that is effective for killing nearly all immature grain moths and beetles, except weevils. The 4 oz per 1000 bu rate is sufficient for tank mixing.

Diacon IGR PLUS. This product is a premix of Centynal EC and Diacon IGR.

Malathion. Although widely used in the past, this product is no longer recommended due to well documented resistance in many stored grain insect populations. Expect malathion to break down in the drier.

Sensat. This product is new to the market, but has been in our evaluation program for several years. Test results show excellent weevil control for up to 12 months. No dryer stability data at this time.

Storcide II. Storcide II is labeled for use on wheat and grain sorghum, but not corn. Protection will degrade with heat and time.

Suspend SC. This product is an older formulation that must be completely suspended before measuring and requires frequent agitation. It provides 3 to 6 months of protection from weevils.

Three-way tankmix (only tested on corn). UGA tests from 2014-2018 showed that a threeway tank mix of Centynal (8.5 oz) plus Diacon IGR (4 oz) plus PBO-8 Synergist (13.5 oz) per 1000 bu will provide 6-9 months of protection from weevils. This is a moderately priced option for growers in markets where other products are unavailable or cost is a limiting factor.

Regardless of the product used, be mindful that grain protectants are not a silver bullet. Shelled corn should be dried to a maximum of 15.5% moisture content before dropping into the storage bin and must be immediately aerated to further reduce moisture content. Chemical applications should only be made to clean grain that will be stored for more than 3 months.

Apply protectants at the bottom of the auger in a course spray to maximize coverage as the kernels are moving up to the top of the bin. Long-term grain storage requires moisture content below 14%, proper housekeeping, use of a spreader when filling bins, and managed aeration.


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