The effect of phosphite (phosphonate) on Phytophthora cinnamommi zoospore prouction in planta

P. cinnamomi is a major pathogen in Western Australia's native vegetation. Phosphite is a cheap fungicide which is non-toxic to animals and has been shown to protect Western Australian plant species against P. cinnamomi. It is proposed to use phosphite in the Eucalyptus marginata forest and in rehabilitated minesites, to control spot infections of P. cinnamomi and to prevent the spread of the pathogen into non-infected plant communities. \n \nMovement of zoospores downslope from an infected area via swimming and transport in surface and subsurface water is thought to be one of the main modes of spread by the pathogen. It is not known whether phosphite is able to inhibit or prevent P. cinnamomi from producing zoospores in planta. If the fungus is still able to produce large numbers of zoospores it may be capable of spreading even if an area has been sprayed with phosphite. \n \nThe aim of this experiment was to determine the effect of phosphite on the production of zoospores from E. marginata and Banksia grandis seedlings which were inoculated with P. cinnamomi.