Polymeric diallyl quaternary ammonium salts for inhibiting banana Fusarium wilt

Banana Fusarium wilt is a typical soil-borne pathogen disease caused by Fusarium oxysporum f. sp. cubense (Foc) and is difficult to control because Foc conidia can survive for many years in soil. Thus, the inhibition of Foc conidia in soil would be an effective and possible way to control banana Fusarium wilt. In this work, three kinds of poly(N,N-diene propyl quaternary ammonium salts) (PDPQASs), namely, poly(methyl butyl diallyl ammonium chloride) (PM), poly(methyl benzyl diallyl ammonium chloride) (PB) and poly(dimethyl diallyl ammonium chloride) (PD), were synthesized, and the antifungal activities on Foc4, the adsorption and leaching properties in soil, and the biotoxicities on silkworms, zebrafish and mice were evaluated. It was found that the three kinds of PDPQAS showed obvious and stronger inhibiting effects on Foc4 conidia, and they were essentially nontoxic to silkworms and mice. Their toxicities were much lower than that of benzalkonium chloride (BC, a typical commercial small molecular QAS) to zebrafish, in which PB showed the best comprehensive properties in antifungal activities and biotoxicities. Benefitting from the stronger polymer-soil interaction, PB could absorb in soil more easily and hardly be leached from the soil, which helped PB stay in the soil more stably and effectively inhibited Foc4 conidia in the long term, giving PB a potential application in the control of banana Fusarium wilt.