Stored Grain Pest Control

Category Definition Category 1C Stored Grain Pest Control

This category is for applicators using or supervising the use of restricted use pesticides to treat stored grain, e.g., grain fumigation.

Learning Objectives Category 1C Stored Grain Pest Control


Unit 1 Stored Grain Pests
  • Describe and name different types of pest insects, pest pathogens and rodents and list their damage, description and biology.
  • Describe the difference between simple and complex metamorphosis.
  • Explain the difference between primary and secondary pests, based on the type of damage they inflict.
  • List differences between the house mouse and the Norway rat.
Unit 2 Preventing Pest Problems
  • List nonchemical methods of preventing or controlling storage grain pests.
  • Explain why new grain should never be stored with old grain.
  • Describe how sanitation, traps, and rodenticide baits may be used to manage rodent control.
Unit 3 Applying the Fumigant
  • Explain how fumigants are used for grain pest control.
  • List what safety precautions should be taken when using methyl bromide, aluminum phosphide, and magnesium phosphide.
  • Describe how to determine if a bin has been properly sealed before grain tank fumigation.
  • Describe what safety precautions should be taken before, during, and after rail car fumigation.
Unit 4 Health Hazards and Safety Precautions
  • Describe what requirements must be met before a pesticide is registered by EPA.
  • Explain who is affected by the new Worker Protection Standard.
  • Explain what is meant by pest resistance to pesticides.
Unit 5 Environmental Safety
  • Explain the potential for groundwater contamination and what precautions must be taken to prevent it.
  • Describe steps to prevent pesticide contamination of wells.
  • List steps to prevent backflow during chemigation.
  • Explain the difference between threatened species and endangered species.
  • Explain the importance of protecting endangered species.
  • Explain how drift can be reduced in agricultural pesticide applications.

Test Your Knowledge Category 1C Stored Grain Pest Control


Unit 1 Stored Grain Pests

Q. Of insects, pathogens and rodents, what is the major cause of stored grain deterioration?
A. Insects are the major cause of stored grain deterioration.

Q. How is temperature a critical factor in insect development?
A. Very cool conditions retard development, and warmer temperatures enhance development.

Q. How might knowing the biology of Indian meal moths help in identifying their presence?
A. The larva leaves a silken thread behind it wherever it crawls. The presence of this webbing identifies the Indian meal moth.

Q. When introducing traps or bait stations into an area for Norway rats, why might you not see immediate acceptance of these foreign objects?
A. The Norway rat is a shy animal and will not normally explore new areas or objects in its environment until it gets used to their presence. The rodent must first become familiar with the objects before it will come into contact with them.

Q. Why are palatable baits recomended to achieve effective control with the house mouse?
A. As with the Norway rat, the senses of the house mouse are excellent. Its eyesight is poor and the rodent is color blind, but the sense of hearing, touch, taste, and smell are acute. This rodent also can detect minute traces of toxicants. Offer it palatable baits to achieve effective control.

Unit 2 Preventing Pest Problems

Q. What storage methods lead to properly stored grain?
A. To minimize the risk of loss, place grain in storage at the proper moisture content. Control the temperature of the grain mass through aeration. Regularly inspect and sample the grain using an accurate method to maintain the stored grain quality.

Q. Why is it important to repair all cracks or holes in grain bins and what is the most permanent way to do so?
A. Grain bins and other grain storage facilities have numerous cracks, crevices, and other harborage where insect pests can hide and develop. Thorough bin sanitation is necessary to clean up these areas, but the most permanent solution is to fill them with caulking material. Roof leaks or large holes in the walls or floor of the bin provide entry points for moisture as well as for rodent and insect pests. Repair this damage promptly to maintain a high-quality grain storage environment.

Q. Why is it important to never store new grain with old grain?
A. Thorough pre-binning sanitation includes removal of grain and grain parts that may be infested with insects.

Q. How often should grain be inspected or monitored for effective management of grain in long-term storage?
A. Make regular inspections of stored grain to evaluate storage conditions and to detect pest infestations before they become severe. Inspect stored grain once a month.

Q. What three basic rodent environmental needs should be manipulated during sanitation as a method of rodent control?

  • Habitat - Change or reduce access to harborage. Eliminate secluded areas where rodents might nest or hide. Favorite hiding places include trash, bushes, pallets, bags, and junk piles.
  • Water - Eliminate available water sources. Rats must have access to free water for survival.
  • Food - Restrict rodent access to food stuffs, such as stored grain, spilled grain, and garbage. This step may entail constant monitoring of structures and site, repairing structures, and cleaning up wastes.
Unit 3 Applying the Fumigant

Q. Explain the process by which grain fumigants ensure healthy crops.
A. Fumigants are chemicals that are in the gas phase at ambient temperatures and pressures. They replace air between kernels with poisonous gas that kills any rodent or insect present. The limiting factor is the amount of time needed to expose pests to the killing concentration of gas. After treatment, the residual gases slowly dissipate by natural air movement, and no residue remains on the grain.

Q. What are the advantages and disadvantages of fumigant use in grain pest control?
A. Advantages include toxicity to insects, rodents, birds, and mammals; they can be applied by several methods and without disturbing the commodity; they are usually available and economical to use. Disadvantages of fumigants include toxicity to humans, requiring trained applicators; they may impair seed germination and may leave excessive residues that exceed tolerance; they may alter taste or odor of the fumigated product; they will not prevent reinfestation after the fumigation.

Q. What steps should an applicator take to ensure an adequate concentration of fumigants to eradicate pests in storage target areas?
A. Effective grain fumigation depends on a number of factors. The primary concern is proper bin seal. Before introducing the fumigants, inspect all bin surfaces for holes or loose seams. You may release a smoke canister within the bin before filling it and mark points where smoke escapes; seal only with sealants approved by the FDA.

Q. What is the suitable grain temperature for fumigation?
A. Do not fumigate when the grain temperature is below 60° F. However, the label on most commercial fumigants will state the minimum temperature at which the product will be effective. Do not guess; use a thermometer to determine grain temperatures. Take several locations and depths because grain temperature will normally vary from one area to another.

Q. Which factors are important in rail car fumigation?
A. Use only solid fumigants in rail cars in transit. Before fumigating any rail car, conduct a preloading inspection and cleaning. Determine what insects are present. Locate and seal small holes and cracks from where fumigants can escape. Check the volume of the boxcar to determine the dosage. As required by law, place a warning sign or placard on each door.

Unit 4 Health Hazards and Safety Precautions

Q. What is meant by phytotoxicity? How is it caused?
A. Some pesticides can burn or otherwise damage the plants to which they are applied. Phytotoxicity may occur because of drift onto nontarget plants, excessive rates, or using low volume (highly concentrated) applications. Sometimes tank mixes of multiple chemicals (that may not be phytotoxic alone) can result in crop damage. Certain weather patterns, such as exceptionally bright, hot, and dry conditions, may increase phytotoxicity. Emulsifiable concentrates may cause some phytotoxicity.

Q. What are the most common causes of delayed toxicity?
A. Delayed toxicity is most often the result of contaminated clothing, leaky spray equipment, inadequate protective clothing and equipment, not properly cleaning spray equipment after each use and, most importantly, not cleaning yourself.

Q. What are sources of oral exposure?
A. Oral exposure sources can be caused by accidental swallowing and is usually from carelessness. Eating, drinking, and smoking while applying pesticides or before properly cleaning hands can also contribute to oral ingestion of pesticides.

Q. What is the minimum requirement of protective clothing?
A. When working with pesticides, wear, at the least, a long-sleeved shirt, long pants, shoes, and socks. When handling pesticide concentrates or mixing and loading the sprayer, a liquid-proof apron and rubber gloves are suggested. Read the pesticide label carefully. The new protective clothing requirements may differ for workers and pesticide handlers.

Q. What kind of gloves should be worn when handling concentrates?
A. Gloves should be unlined and made of a waterproof material that does not contain any cotton, leather or other fabric that will absorb chemicals. Sleeves should be worn on the outside of the gloves.

Q. What types of hats and boots should be avoided when applying pesticides?
A. Hats should be easy to clean or they should be disposable. Avoid hat fabrics that absorb liquids. Unlined rubber boots are a good investment for pesticide applicators because they are waterproof and easy to clean. Work shoes made of canvas or leather should be avoided, because they absorb pesticides and cannot be decontaminated.

Unit 5 Environmental Safety

Q. What are three kinds of non-point source pesticide pollution?
A. The three kinds of non-point source pesticide pollution are runoff, run-in and leaching. Runoff occurs when rainfall or irrigation rates exceed the rate at which water can be absorbed into the soil. When runoff occurs, pesticide residues can be carried off the field and into surface waters. Run-in is the transport of pollutants to groundwater by a direct route, such as through a sinkhole or an abandoned well. Leaching occurs when contaminants are carried through the soil with excess water that percolates below the crop root zone and into the groundwater. Leaching is most common in sandy, permeable soils.

Q. What is the difference between threatened species and endangered species?
A. Plants or animals in danger of becoming extinct are classified as 'endangered'. Plants or animals of intermediate rarity are classified as 'threatened'. Threatened means that the possibility of becoming endangered exists if the population declines.

Q. What type of pesticide containers are accepted for recycling?
A. Only empty, dry plastic containers that have been triple- or pressure-rinsed will be accepted for recycling.

Q. What are the two kinds of drift?
A.Two types of drift are associated with pesticides. The most common, drift of spray droplets or dust particles, is directly affected by spray pressure, nozzle opening size, wind velocity, and pesticide formulations. Drift of a chemical with high vapor pressure is termed "vapor drift". Vapors or gases can drift in harmful concentrations, even without wind. Fumigants such as methyl bromide must be confined so they will not drift from the treated area.

Q. What are the four equipment requirements of a chemigation system?
A. The chemigation act requires growers to install four main safeguards on their chemigation equipment to prevent contamination of groundwater:

  • An interlock, mechanical or electrical, must connect the chemical injection equipment with the irrigation pump. Thus, if the irrigation pump stops so will the chemical pump, preventing too much chemical from being pumped into the lines. In addition to stopping groundwater contamination, this interlock also prevents too much fertilizer or herbicide from injuring the chemigated crops or plants.
  • A check valve must be installed between. the irrigation pump and the point of injection of the chemical. This prevents water that has chemical mixed with it from flowing back into the well or other water source. Any system that does not have this provision is risking contamination of everyone's water. A vacuum breaker must be installed behind the check valve. This prevents back siphonage of the chemicals by releasing the siphon on the water line when the pump is cut off.
  • A low-pressure drain must be installed behind the check valve and preferably behind the vacuum breaker. This prevents backflow into the well or water source when the system is not under pressure or when the check valve leaks slightly during pumping.

Selected Web Sites The following are web links containing information pertaining to Category 1C Stored Grain Pest Control


Resources found at Clemson University
  1. Regulatory Services Department of Pesticide Regulation
  2. Extension Pesticide Information Program
  3. Extension Pesticide Information Program links to pesticide labels, MSDSheets, and chemical fact sheets
  4. Extension Pesticide Information Program links to listings and information about restricted use pesticides (RUPs)
  5. Research & Education Centers (RECs) (Edisto, Pee Dee, Sandhill and Coastal)