Relationships between site factors and distribution of Phytophthora cinnamomi in the Eastern Otway Ranges, Victoria

Abstract

The Eastern Otway Ranges, Victoria is an area recognised for its significant flora and fauna communities. An area of about 7000 ha, the Anglesea heathlands has been listed on the register of the National Estate. Although symptoms of the plant pathogen Phytophthora cinnamomi have been recorded in the area since the 1970s, the extent of infestation and its effects have not been documented. The aims of this study were to assess the distribution of infestation, identify the relationship of plant infection to site variables and to identify evidence of spread of the pathogen. The presence of P. cinnamomi was assessed at 50 study sites by a visual evaluation of the vegetation, using species such as Xanthorrhoea australis (Austral grass tree) and Isopogon ceratophyllus (horny cone bush) as indicator species. Soil and plant tissues were assayed for the presence of the pathogen by cotyledon baiting and immunoassay methods. Phytophthora cinnamomi was isolated at 76% of the study sites from the floristic communities identified: heathy open forest; heathy woodland I and II; Bald Hills heathland; riparian open forest. There were significantly more diseased sites at lower altitudes. The pathogen is widely spread and causing disease throughout the area, but at present often only in small patches. There is an urgent need for disease management to protect the significant communities. These findings suggest that management actions such as mapping current infestations, closing tracks and implementing vehicle wash-down points are required.

Habitat suitability of soils from a topographic gradient across the Fitzgerald River National Park for invasion by Phytophthora cinnamomi

“…Abiotic and biotic factors influence habitat suitability as constrained by the species autecology (Chabrerie et al 2007). Elements of landscape structure such as plant community composition, topographic position, aspect, slope and disturbance affect disease expression by P. cinnamomi (Podger 1972, Shearer andDillon 1996a;Wilson et al 2000;Moreira and Martins 2005). The information of soil habitat suitability from this study need to be combined with other elements of landscape structure in order to predict P. cinnamomi risk and hazard in disease-free areas of the Fitzgerald River National Park.…”

Distribution of Phytophthora cinnamomi at different spatial scales: When can a negative result be considered positively?

“…An implication is that the pathogen can be present within the landscape without causing visible signs of patch death at any particular time. Wilson et al (2000) also suggested the presence of P. cinnamomi need not coincide with patch death, because four sites in the Eastern Otway Ranges in Victoria, with positive responses for P. cinnamomi, had vegetation that appeared healthy. This should not, however, be interpreted to suggest that locations where P. cinnamomi is present without apparent effects will remain free from canopy disease.…”

Spatial model for predicting the presence of cinnamon fungus (Phytophthora cinnamomi) in sclerophyll vegetation communities in south-eastern Australia

“…The location of a site corner was determined with use of a global positioning system (GPS) receiver, and a measuring tape was used to mark out the other corners. Variables were recorded in the sample area at each site as described in Wilson et al . (2000) and included: aspect, slope, altitude, distance and elevation of sites from roads or tracks, relative elevation of site, road categories and frequency of use.…”

“…Three spatially separated samples were taken where possible from each study site and returned to the laboratory where three subsamples (50 g) from each soil sample were placed in separate plastic beakers for analysis. Two isolation techniques, cotyledon baiting on selective medium and immunodipstick assay, were used to test for the presence of P. cinnamomi in the soil samples (Wilson et al 1997(Wilson et al , 2000.…”

“…, 1994Wilson 1991;Laidlaw 1997). Analysis of independent site variables and their relationship to the presence of P. cinnamomi showed no significant influence of aspect, slope, land system, vegetation classification, soil texture or distance from soil to clay level (Wilson et al . 2000).…”