Abstract
The use of phosphite at concentrations of 2 and 4g a.i.1L proved to be successful in controlling the spread of Phytophthora cinnamomi within different vegetation communities at Anglesea (Alcoa lease area) and Tidal River (Wilson's Promontory National Park). At nine sites, phosphite was sprayed to runoff with a Solo® 422 motorised backpack sprayer with 2L125m' quadrat. Using aerial and ground photography, quadrats were monitored over a two-year period to determine changes in species abundance due to the pathogen. There was a significant difference (p<0.05) between the proportions of healthy Xanthorrhoea australis in phosphite sprayed quadrats (2 and 4g a.i.1L with 0.5% surfactant) compared to those sprayed with a control (water and 0.5% surfactant, water only). Vegetation in quadrats where P. cinnamomi was present was protected by phosphite for 2 years (4g a.i.IL) and 12 months (2g a.i.IL). However, vegetation in quadrats where the pathogen was present died where phosphite was not sprayed. Phosphite provided protection for X australis, Isopogon ceratophyllus and Monotoca scoparia (3 species highly susceptible to P. cinnamoml). From the results of this research we recommend the use of phosphite in susceptible vegetation communities with 4g a.i'!L phosphite to assist with already existing management strategies for the protection of Victorian heathlands and forests from P. cinnamomi.