Towards Eradication of Phytophthora cinnamomi Using a Fallow Approach in a Mediterranean Climate

Abstract

While eradication from haul roads was achieved, more work is required to eradicate P. cinnamomi from stockpiles and bunds. We can now implement different management strategies to the construction of bunds and stockpiles to facilitate eradication. Infestation by Phytophthora cinnamomi results in large financial and management constraints to environmental managers. This pathogen was considered impossible to eradicate until recent success with treatments including host removal, herbicide and fungicide application, soil fumigation and physical root barriers. We investigated the most benign of these treatments; keeping the area devoid of living host material. In a Western Australian mine site within a Mediterranean climate, haul roads, stockpiles and roadside bunds had P. cinnamomi colonised Pinus stem plugs buried at multiple depths. Over time, we examined the effects of soil moisture and temperature in different soil conditions and types to compare the recovery of the pathogen. Results: Within 12 months, the pathogen could not be recovered from the haul roads. In the stockpiles, depth produced significantly different results. In 3 of the 4 sites, the pathogen was not recovered at 10 cm after 20 months. By 12 months, at 50 cm, there was an 80% reduction in recovery, but only one stockpile had no recovery from 50 cm, which occurred by 36 months. Bunds were up to 1.75 m high and had variable results for plugs buried at 30 cm, influenced by height, the types of soils and shading. One of the smallest bunds was the only bund where the pathogen was not recoverable (by 22 months). This study provides strong support for using a fallow period to reduce or eliminate P. cinnamomi inoculum.

Multivariate Bayesian analysis to predict invasiveness ofPhytophthorapathogens

“…Some examples of local control of Phytophthora species include management of sudden oak death cited further above (also see Cunniffe et al, 2016; Filipe et al, 2012) and use of microbiota biocontrol agents to control the impact of P. capsici on agricultural products (Cucu et al, 2020). Other examples include reducing the spread of the soil pathogen P. cinnamomi during mining operations (Colquhoun & Kerp, 2007), its eradication from mine sites and sensitive ecosystems (Dunstan et al, 2010, 2020), and the use of phosphite to control its impact on trees (Crane & Shearer, 2014). Further examples can be found in the literature.…”

Impact of Phytophthora dieback on a key heathland species Xanthorrhoea australis (Asphodelaceae) (austral grasstree) and floristic composition in the eastern Otways, Victoria

“…However, treatments including host removal, herbicide application, fungicide application, soil fumigation and physical root barriers have been demonstrated to eliminate the pathogen to depths of 2 m from up to 18 months to 8 years after treatment, some in forest sites and National Parks (Dunne et al 2011;Dunstan et al 2010Dunstan et al , 2020Crone et al 2014). A fallow approach together with exposure to high summer soil temperatures in a mine site has also been found to eradicate the pathogen within 12 months on haul roads and result in declines in recovery from bunds and stockpiles but not as rapidly or to the same degree (Dunstan et al 2010(Dunstan et al , 2020. Although these studies demonstrate the potential to eradicate this pathogen, in many cases the costs and risks would be considered prohibitive.…”