The present invention provides a biologically active combination for agricultural applications, comprising A) at least one biocidal, agriculturally acceptable active compound and B) a bioactivator for the active substance according to A) and C) if appropriate, customary auxiliaries and additives, which comprises the use, as bioactivator B), at least one compound of the formula (I)
R—C(O)NH—(CH2)a—N+(R1,R2)—(CH2)b—COO— (I)
in which R is a hydrocarbon radical having 6 to 22 carbon atoms, preferably 8 to 18 and in particular 10 to 14 carbon atoms, which is optionally branched and/or contains multiple bonds and/or functional groups,
[0001]- R1, R2 independently of one another are C1-4-alkyl radicals, in particular —CH3, a is 1 to 5, preferably 2 or 3, b is 1 or 2, in an effective concentration.