Fumigation techniques

Fumigation

The most effective way to reach pests in their most remote hiding places is through fumigation, the use of poisonous gases to kill pests in an enclosed area. To be effective, fumigants must reach target pests as gases. Fumigants are "wide-spectrum" pesticides, killing all species of arthropods and rodents that are likely to be found in a building. They are also volatile pesticides whose vapors enter the insect's body through the body wall or breathing system. Fumigants penetrate to many areas of a building not reached by sprays or dusts, even penetrating to the burrows of wood-infesting insects, as well as to the center of tightly packed commodities, such as tobacco in hogsheads, bales, cases or grain in large silos or bulking bins. A fumigant gas generally does not leave unsightly, odorous, or hazardous residues.

Types & Nature of Fumigants

A number of fumigant active ingredients formerly used have either been canceled entirely or have had their uses strictly limited in the U.S. All space fumigant products, and several soil fumigant products, especially those containing chloropicrin and/or methyl bromide, are now labeled Restricted-Use. Fumigants are broad spectrum pesticides that can act as respiratory poisons, anesthetics or narcotics, or enzyme poisons. They are chemically simple molecules, but they can exert potent and wide-ranging effects on the target organisms. Because of their gaseous nature and acute inhalation toxicity, fumigant products are labeled as Toxicity Category I with the signal word Danger, or Danger-Poison with the skull and crossbones symbol. The following section lists and describes the active ingredients that are still available and legal to use.

Methyl bromide

            Is formulated as a liquid and vapor under pressure. It is odorless, non-flammable, and

generally not corrosive nor irritating to eyes as a vapor. Because it is highly toxic by inhalation and also odorless, many formulations contain chloropicm as a warning agent on non-food products. Methyl bromide products are used both for space and soil fumigation. If trapped inside tight clothing next to skin, methyl bromide can cause severe skin burns. Do not use it to fumigate materials that contain sulfur (e.g., hair, fur, leather, and rubber goods) because of an undesirable chemical reaction with sulfur. It is a good idea to test a small piece of the material to be fumigated to determine if it might react; that is, to actually conduct a small-scale fumigation on the suspect material.

Aluminum phosphide

They are space, commodity, and rodent burrow fumigants. The formulations include pellets, tablets, prepacs, prepac ropes, bags, and plates. They are solids that react with moisture to liberate hydrogen phosphide (phosphine), which is a gas highly toxic to insects, humans, rodents, and other animals. It is thus absolutely necessary to keep aluminum phosphide and magnesium phosphide products DRY in storage. Since magnesium phosphide is more reactive than aluminum phosphide, it is generally recommended for fumigation under cooler and/or drier conditions. Phosphine ignites spontaneously in air at concentrations above 1.8% by volume. Some formulations include ammonium carbarnate, which liberates ammonia gas and carbon dioxide to reduce the fire hazard posed by phosphine. Ammonia also serves as a warning agent. Sullfuryll fluoride is a space fumigant used primarily to control wood-destroying insects. It is a colorless, odorless, non-flammable gas formulated in cylinders under pressure. Special monitoring equipment is needed to use Vikane, the product containing sulfuryl fluoride as its active ingredient. Registration is expected soon to permit sulfuryl fluoride under the name Profume to be used to fumigate flour mills and similar areas. DDVP, also known as dichlorvos, is a contact and stomach insecticide with some fumigant action and is used to protect stored products. Since it is an orgaophosphate it should be handled with the precautions used with other organophosphate products. It is somewhat corrosive and should be kept dry in storage. DDVP is under Special Review by the Environmental Protection Agency.

Ethylene oxide is a colorless, toxic, flammable liquefied gas that can be used as a fumigant on spices, black walnuts, and copra. It is formulated with carbon dioxide or dichlorodifluoromethane to reduce flammability.