Active agent formulation, for protecting plant, comprises at least one plant protection active substance, a solvent or a propylene carbonate/gamma butyrolactone. Independent claims are included for: (1) the preparation of the active agent formulation; (2) a method for increasing the efficiency of the plant protection active substance or its combination, comprising formulating the plant protection active substance in the active agent formulation; and (3) a method for protecting plants before parasitic attack, comprising treating the plants or their habitat with the active agent formulation. ACTIVITY : Plant Protectant. MECHANISM OF ACTION : None given.