What agricultural practice involves using specially refined oils for smothering pests on plants?

The practice that involves using specially refined oils to smother pests on plants is the use of horticultural oils. Horticultural oils are lightweight, refined mineral oils or plant-based oils that are applied to plants primarily to control pests such as aphids, spider mites, and whiteflies. These oils work by coating the pests and obstructing their breathing pores, leading to suffocation.

Horticultural oils are favored in integrated pest management programs because they can be less toxic to beneficial insects when applied correctly and they break down rapidly in the environment. The oils also conform to organic farming practices when they meet certain standards, making them a preferred choice for growers aiming for sustainability.

Hydraulic spraying refers to a method of applying pesticides but does not specify the type of material being sprayed. Insect growth regulators disrupt the development of insects but do not rely on oils for pest control. The use of insecticides encompasses a broad range of chemicals designed to kill insects but does not specifically target the oil-based approach used in horticultural oils. Therefore, the correct choice highlights the unique role of horticultural oils in gently and effectively managing pest populations on plants.