Minimizing the spread of a soil-borne plant pathogen during a large-scale mining operation

The challenge for Alcoa's mining operation is simply stated but not so simple to implement; to be able to extract bauxite in large open-cut mine pits without spreading the soil-borne pathogen Phytophthora cinnamomi. The mining operation clears about 550 ha of Jarrah forest a year and moves about 6 million m 3 of soil. Phytophthora cinnamomi has a scattered distribution in the Jarrah forest that results in most mine pits having infested and uninfested portions. Also, there are generally large areas of uninfested forest adjacent to mine pits. Consequently, the potential to spread the pathogen into uninfested forest is very high. This paper describes the development of protocols to prevent spread of P. cinnamomi during mining and restoration, and tools used to assess the success of the program. Monitoring 169 km of the perimeter of mine pits for the introduction of the pathogen to uninfested forest showed very low levels of spread; 0.0006 ha for every hectare mined. The potential for further spread from the new infestation was also estimated by calculating the area of uninfested forest directly downslope from the infestation; this level of spread was 0.002 ha for every hectare mined. We believe that the findings of this study go beyond the issue of disease management during mining. We believe that it is an example of the mining industry recognizing a large threat to the environment and, through a systematic and committed approach, dramatically decreasing the size of the threat to achieve a successful outcome.