Assimilation of Phosphite by Agrostis stolonifera L. and its In Vitro Effect on Microdochium nivale

Abstract

Introduction Microdochium nivale (Fr.) Samuels and Hallett, (teleomorph Monographella nivalis (Schafnitt) is a major pathogen of cool-season turfgrasses (Vargas, 2005).The search for new or improved means to reduce susceptibility to M. nivale is an ongoing target for turfgrass research. One possible means is the use of phosphite (PO3 3, Phi) which is derived from phosphorous acid (H3PO3) and commonly modified with potassium hydroxide (KOH), forming KH2PO3 or K2HPO3 (potassium phosphite)(Ouimette and Coffey, 1988). In turfgrass management these form the active substances in numerous products currently marketed as either fungicides or fertilisers and used as a component of an integrated approach to disease management (Landschoot and Cook, 2005). Phi has proven efficacy in reducing susceptibility to oomycete pathogens in numerous plant species. While there are data showing similar success in controlling ascomycete pathogens (Hofgaard et al., 2010) and reports of Phi mediated reduction of M. nivale in turfgrass (Dempsey and Owen, 2010), studies into Phi uptake in turfgrass and its possible direct inhibition of M. nivale are lacking. The objectives of this study therefore, were to determine the mode of assimilation of Phi in A. stolonifera L. and to assess the inhibitory effects Phi may have on the in vitro mycelial growth of M.nivale.