Farm-stored corn insect mamagement

Robert G. Bellinger

The quality of farm-stored grains is at its peak when it is loaded into the bin for storage. After loading the best you can do is to try to maintain this level of quality. Thus, it is important to maximize the quality of your corn prior to storage. At harvest make sure that your harvesting equipment is adjusted to minimize breaking or cracking the beans.

Only load corn into a thoroughly cleaned, empty bin. Don’t load grains on top of older grains! When loading corn into the storage bin make sure your loading auger and mechanical spreaders in the bin are in good condition and will not damage the corn when loading. Run the auger at full capacity (run at a slow speed) to minimize breaking the kernels. And the cleaner and drier the corn is going into the bin the better.

Do not overfill the bin. Level the corn in the bin as soon as it is filled and immediately begin aeration to cool the corn. Poorly controlled temperatures are the most important cause of stored all stored grains, including corn, going out of condition. Get the corn cooled down to the outside air temperature as soon as possible. Keep the bin temperature no more than 10 – 15oF of the outside temperature during storage. Ideally the temperature should be maintained at 35 - 40oF.

Proper harvest, loading and storage of corn is critical for managing potential insect infestations. Proper storage management provides the best control for the cost. It is important in any insect management system to not rely solely on insecticides. This is particularly true for stored grains, as there are few insecticides registered in this use area, and fewer still for the individual stored commodities. Also, insecticide resistance has already made at least malathion essentially useless in many stored grains environments. Malathion is not recommended on stored corn (see notes below.)

Insects will stop feeding and reproduction at temperatures below about 50oF. Because corn is harvested when temperatures can still be fairly warm, immediate aeration to get harvested corn to ambient temperature is critical to help prevent insect infestations. Even corn held at the moisture levels that will not allow mold growth, properly cooled and dried corn can still be infested by at least Indian meal moth. This moth infests the grain from the top of the bin. This moth can be controlled using DDVP resin strips in the head space of the bin, using 1 strip per 1,000 cubic feet (controls adults only). Change strips monthly in warm weather. You may alternatively, or also, use a Bacillus thuringiensis (Bt) product (for example, Dipel) as a top dressing (gain surface treatment) applied immediately after bin loading (controls larvae only.)

Diatomaceous earth products may also be use here but monthly treatments will be needed.
Properly loaded corn should be stored in thoroughly cleaned and surfaced treated bins (bin surface treatment). A grain protectant (Atellic only) can also be used when loading the corn. However, even if both of these procedures are followed, do not fail to regularly check the beans – check storage temperature and moisture levels and flying moths, and for surface crusting.

Farm-Stored Corn Insect Management – 2008

These recommendations are based on active ingredients. These recommendations are not a substitute for carefully reading the pesticide label. Other registered products not mentioned here may be as effective.

Pest or Application Type

Active Ingredient(s)
(Products)

Rates
READ and FOLLOW the LABEL INSTRUCTIONS

Site(s)

Re-entry Interval
(REI)

Comments
(And see Notes after this table)

Bin Repair & Sanitation

Interior and exterior of grain storage bins prior to loading.

Sanitation is critical. Repair (fix and fill holes, cracks) and thoroughly clean bins before loading with grain. Most pesticide product labels note sanitation as a pre-treatment procedure!

Empty Bin Residual Sprays

(Bin interior surface treatment)

beta-Cyfluthrin
(Tempo 20WP, Tempo 2.0, Tempo SC Ultra)

Chlorpyrifos-methyl + deltamethrin
(Storcide II)

Diatomaceous earth (DE)
(Insecto)

Spray empty, cleaned bin to run-off with low pressure sprayer (“garden sprayer”) (less than 50 psi) with flat fan nozzle tip. One gal. spray covers 750–1,000 sq. ft.

Bin surfaces – 1.8 fl. ozs. for 1.0 gal. of spray solution applied

1 lb./1,000 sq.ft. of surface

Empty bin only

Empty bins

When sprays have dried

Do not treat any grain with Tempo. Do not store soybeans in bins treated with Tempo.

Must be applied from the outside only with downward spray with automated equipment.

Applied through aeration fan. May meet organic requirements.

Empty Bin Fumigation

Aluminum phosphide -
phostoxin gas
(Phostoxin; Phosfume; Weevil-cide; pellets /tablets)

Follow label, applicator manual instructions exactly

Insects which infest stored crops

Follow label, applicatormanual proceduresexactly

Fumigate empty bin after thorough bin clean-out and interior residual treatment if necessary. Extremely toxic RUP with strict application procedures. No residual control.

Pest or Application Type

Active Ingredient(s)
(Products)

Rates
READ and FOLLOW the LABEL INSTRUCTIONS

Site(s)

Re-entry Interval
(REI)

Comments
(And see Notes after this table)

Grain Protectants

(Direct grain / Admixture treatment)

Pirimiphos-methyl
(Actellic 5E)

s-methoprene
(Diacon II)

Diatomaceous earth (DE) (e.g. Insecto)

9.2 – 12.3 fl.ozs. (6 – 8 ppm) in 5 gal. water for 1,071 bu. ( 30 tons)

8 to 14 fl. ozs./5gal. water/1,000 bu. grain – rate varies with kind of grain.

1- 2 lbs./ton of grain to top 2-3 ft. of grain.

Corn, grain sorghum only

Wheat, corn, sorghum, (milo), oats, barley, peanuts

When sprays have dried

One (1) treatment per load of grain only. Use calibrated applicator

Controls larvae only

May meet organic requirements.
Treatment varies with time of harvest, anticipated storage time.

Grain Top-Dressing

(Stored grain surface treatment, especially for Indian-meal moth larvae- Applications are to leveled grain)

Pirimiphos-methyl
(Actellic 5E)

(s)-methoprene
(Diacon II)

Bacillus thuringiensis (Bt) (Biobit HP, Dipel DF, Javelin WG)

Diatomaceous earth (DE) (Insecto)

3 fl. ozs./2 gal. water/1,000 sq.ft. (3.0 ppm)

0.2 teaspoons or 0.1ml./1,000 sq.ft.

1 lb./10-20 gal. water/1,000 sq.ft.; see label

4 lbs./1,000 sq.ft.

Corn, grain sorghum only

When sprays have dried

Clear webbing, break-up crusting. Apply 1 gal. and rake into top 4 inches of grain; apply second gal. to raked surface.

Use only enough water to give coverage – Do not flood grain surface. Controls only larvae.

Apply to surface and rake into top 4 inches of grain; see label instructions. Controls only larvae. May meet organic requirements.

Especially for Indian-meal moth. Apply at monthly intervals. May meet organic requirements.

Filled Bin Fumigation

Aluminum phosphide -
phostoxin gas
(Phostoxin; Phosfume; Weevil-cide; pellets or tablets)

Sulfuryl fluoride gas (Profume)

Follow label, product applicator manual exactly

Insects which infest stored crops

Fumigant detection, post-treat ventilation.
Follow label, product applicatormanual procedures for all products.

Extremely toxic RUP. Strict application procedures including placarding, fumigant detection, other required measures.

Extremely toxic RUP. Strict application procedures fumigant detection, other measures.

Note: Product use sites - Read the label carefully! Use sites vary widely from product to product. Some products may only be used to treat grain storage bin surfaces and not grain; few products may be used for both applications. Grains that may be treated vary with product.

Note: Product rates - Read product labels carefully! Rates vary with formulation of product used, use site/crop being stored, anticipated storage time, and pest species, and pest development stage. Some products may only have one (1) application made to a load. Period of control can vary with pest insect species and is shortest at the lowest rates.

Note: Pests controlled – Read the label. Not all products control all pests, especially at the lowest rates. Bacillus thuringiensis (Bt) products control only caterpillars (moth larvae), and not beetle grubs. Control will be slow.

Note: Formulations – Read the label. Choose the correct formulation. Be sure you have the necessary application and safety equipment and PPE to make an application with the product formulation you consider. Some formulations may not be applied directly to grain. Some products may be applied with water or food-grade oil or soybean oil, usually except for peanuts.

Note: Insecto (a diatomaceous earth product) – “Insecto Control Plan” calls for dusting the empty bin, treating the bottom 2 feet of grain, treating the top 2 feet of grain, top-dressing leveled grain with this product at labeled rates. Inspect grain bi-weekly. Organic Materials Review Institute (OMRI) Listed.

Note: Actellic 5E – only one (1) application method is allowed per load. Only one (1) application allowed per load.

Note: Diacon II (s-methoprene) – Insect growth regulator controlling larvae only. Lowest rates give control for less than 6 months. May be applied with water or food-grade oil or soybean oil, except for peanuts. Product may be applied with an insecticide controlling adults. Read the label(s).

Note: Fumigants are the most effective way of controlling insect infestations in stored grain; however, fumigants provide no residual control. Fumigants are Restricted Use Pesticides (RUPs) and may be purchased and used only by licensed applicators. These pesticides are Danger, Danger/Poison labeled because of acute toxicity. Fumigants have strict application requirements via the label and applicator manual. Product-specific training and/or product company supervision may be required, especially for liquid and gas formulations.

Note: Malathion is registered for empty bin treatments (labeled EC formulations only) and for grain protectant treatments (labeled dust formulations only) for some grains. However, malathion is not being recommended here as it is not seen as effective by many because of wide-spread insect resistance to it, especially in the Indian-meal moth. Malathion also degrades rapidly at high temperatures. Further, international tolerances for malathion on grain have been lowered and are now much lower than U.S. tolerances, effectively making malathion treated grain unmarketable outside of the U.S. Grain buyers are telling growers that they will not accept grain treated with malathion.

Grain Bin Surface Areas and Capacities - R.G. Bellinger 01/08

Bin Diameter (Feet)	Grain Surface Area or Bin Floor Area (Square Feet)	Approximate Surface Area of Empty Bin (Square Feet)	Bushels per Foot of Bin Height	Approximate Bin Head-space (Volume of a cone - Cubic Feet)
15	177	(Height x 47) + 354	141	59 x cone height
18	254	(Height x 57) + 508	204	85 x cone height
21	346	(Height x 66 ) + 692	277	115 x cone height
24	452	(Height x 75) + 900	362	151 x cone height
27	573	(Height x 85) + 1146	458	191 x cone height
30	707	(Height x 92) + 1400	566	236 x cone height
33	855	(Height x 104 ) + 1710	685	285 x cone height
36	1,018	(Height x 113) + 2000	815	339 x cone height
42	1,385	(Height x 132) + 2770	1109	462 x cone height
48	1,810	(Height x 151) + 3,620	1448	603 x cone height
54	2,290	(Height x 170) + 4580	1833	763 x cone height
60	2,827	(Height x 188) + 5654	2263	942 x cone height