[R] Method of control in which the means for eradication of pests (mainly chemicals) are used only when actually needed, i.e. when the economic injury threshold is about to be reached or exceeded.
Rational control can be opposed to "preventive medicine" or "insurance" and is undertaken on a regular, calendar basis. Integrated control is derived from it.
HYPPZ on line: Species (scientific names), Pests (common names), Glossary, Crops.