Host range of the stem canker pathogen Luteocirrhus shearii mainly limited to Banksia

Isolations from diseased plants and controlled inoculations indicate that the host range of the canker pathogen Luteocirrhus shearii is mainly limited to Banksia. Branches exhibiting canker symptoms were sampled from the Geraldton Sandplains, Swan Coastal Plain, Jarrah Forest, Warren and Esperance Sandplains bioregions of the South-West Botanical Province of Western Australia (n = 1,351). Luteocirrhus shearii was isolated from only Proteaceae and did not infect wound inoculated Myrtaceae. The pathogen was isolated from or formed extensive lesions in 15 Banksia species. Differences in isolation frequency and rates of lesion extension of L. shearii between Banksia spp. may indicate different modes of infection by the canker pathogen. By exerting top-down control of population dynamics of Banksia communities from lower trophic levels, L. shearii would substantially alter host species diversity and in turn ecosystem processes. Predicted climate change could influence future biotic reorganisations following L. shearii invasion. What determines the limited host range of L. shearii compared to the community of organisms on Banksia needs to be determined.