Notes section

Abstract

The distribution of Phytophthora cinnamomi and the disease with which it is associated have been shown to originate in Victoria from the use of infected soil or gravel, or infected drainage water, and to have extended along roads and down gullies or table drains. The presence of the pathogen in soil frequently leads to disease in dry sclerophyll and coastal forests where most species, including dominants of the tree and shrub strata are highly susceptible. In shallow, poorly drained soil, disease may cause a complete change of plant community from shrubby sclerophyll forest to grassy woodland, with the extinction of a number of native species.Inoculation experiments with combinations of tolerant and sensitive eucalypt species in a controlled environment showed that susceptible species were rapidly eliminated from infected soil. Field inoculations using washed mycelium or infected topsoil have produced typical dieback disease in both strata of the forest.The disjunct distribution of the fungus and the susceptibility of the forest flora are evidence of the recent introduction of a pathogen that disturbs the equilibrium of the Victorian dry sclerophyll forest. Observations are not compatible with the view that P. cinnamomi is a common component of the soil microflora.