Grain farmers invest too much time, energy and money into producing their crops to allow insect pests to reduce volume and quality in on-farm storage facilities.
Farmers have good reasons to pay close attention to protecting stored grain, says Texas AgriLife Extension entomologist Roy Parker.
Managing grain in storage facilities allows a producer to “develop a reputation as the individual from which to purchase grain,” Parker said during the recent Texas Plant Protection Association annual conference in College Station.
“Insect management is one way to achieve that reputation, but it requires attention to all aspects of the stored grain operation,” he said.
Insect damage causes multiple problems including loss of yield through destroyed kernels, reduced quality from insect parts, increased heat (10 to 15 degrees higher), more moisture and mold, odor, additional dust and as much as 5 percent weight loss per year. All those issues may mean a 16 percent loss in market value in just one year.
Parker recommends an integrated pest management approach to controlling insects in stored grain. IPM tactics include:
- Set harvest equipment to reduce trash, fines and broken kernels.
- Harvest at a safe, low moisture level but not so low that grain cracks.
- A storage moisture level of 13 percent to 14 percent is the highest level to allow (lower for certain grain types).
- Practice sanitation and treatment of harvest equipment, grain carts, augers, transport trucks, rail cars, barges and ships. Sanitation should include: clean harvest equipment; clean hauling equipment; and clean pits, augers and conveyors
- Immediate sanitation inside and outside storage.
- Design construction for ease of cleaning and tight seal for effective fumigation. Note: construct storage bins so that a pressure can be held for an extended period when sealed for fumigation or have at least one bin for such use.
- Treat empty bins with insecticide about two weeks before loading (Tempo, Storcide II, Silicon dioxide, malathion).
- Apply insecticide to grain as it is loaded into storage after drying. Note: consider protectant use where grain will be stored under warm conditions for more than five months (Actellic + Diacon, Storcide II, and others).
- Remove grain peak and “core” round bins.
- Apply top-dress insecticide if not used on the rest of the grain.
- Aerate to remove harvest heat followed by cooling to 60°F or less (40°F is best).
- Monitor grain temperature to find “hot spots” (thermocouples).
- Inspect grain for insects once a month when it is cool (less than 60°F) or twice a month (at more than 60°F).
- Keep records of insect numbers by species (per unit volume), location in bin, grain moisture, grain temperature, and bushel weight.
- As a general rule apply fumigant when one primary pest or five secondary pests per quart sample of grain are detected. Note: Higher numbers of some insects such as psocids and rusty grain beetle can be tolerated. Note: Wheat may need to be fumigated at one insect per quart sample.
- Do not store “new” grain on top of “old” grain. If it must be done apply fumigant to “old” grain first.
He said producers should know the flow rate of the grain to assure proper insecticide application in-stream.
Parker said producers may choose from several products for grain stream treatment. Options include: Actellic for corn and grain sorghum; Storcide II for barley, oats, rice, sorghum and wheat; Diacon II, which is generally not used alone; and Contain. He said a label for spinosad may be on the horizon.
Fumigants include Phosphene gas and Profume.
Parker said tests on protectant insecticides show:
- Actellic was effective on all insects except lesser gain borer.
- Diacon II was effective on larval stage of all insects except for weevils.
- Combination of Actellic + Diacon II was very effective.
- Silicon dioxide was effective but reduced bushel weight and made grain handling more difficult.
- Liquid spinosad provided effective control (still waiting on approval by Japan).
- Rates based on a chemical cost of 4 cents per bushel were effective for 10 to 12 months in storage.
Parker said when producers clean out bins they should move any old grain or other debris away from the facilities. “Get it all offsite,” he said.
Parker also commented on storage bags and potential for insect damage. “Moisture is used up in the bags by respiration, and carbon dioxide levels increase so we’ve had no insect problems,” he said.
Maximum storage time in these bags has been about six months. “We’ve had no insect problems so far. In fact, weevil numbers dropped slightly each month corn was stored in the bags.”
He said it’s critical that producers do not place the bags where water will stand.
“We also expected some problems with animals, especially feral hogs. We’ve seen some problems with rats and raccoons, but no hogs. Also, we can seal up damaged areas.”
Parker advised farmers storing grain in bags to check frequently for animal damage, moisture and temperature.