Define "fumigation" in pest control practices.

Fumigation in pest control practices involves the use of gaseous pesticides, known as fumigants, that are applied in an enclosed area to eliminate pests. This method is highly effective for treating a wide range of infestations, especially in situations where other methods, such as surface sprays or traps, may not penetrate effectively into materials or spaces where pests may hide.

The key aspect of fumigation is the containment of the gas in a sealed environment, which allows the gaseous pesticide to disperse thoroughly and reach all areas, including cracks, crevices, and inside materials where pests are present. Because the fumigant is in vapor form, it can permeate these spaces and ensure that pests, which might be resistant to other treatment methods, are effectively eradicated.

The other options describe different pest control methods that do not align with the definition of fumigation. For instance, surface spraying refers to applying pesticides on surfaces rather than using gas. Physical capture methods utilize traps and other devices to catch pests and do not involve chemicals at all. Preventive treatments aim to deter pests before they infest an area and do not involve the targeted eradication that fumigation provides.