Caliciopsis canker: an emerging disease in pine stands
Nicola Luchi: Institute for Sustainable Plant Protection - CNR
<div>Caliciopsis canker, caused by <em>Caliciopsis pinea</em>, have been increasingly observed in plantations of <em>Pinus radiata</em> in Italy, and occasionally on <em>P. pinaster</em>. In Europe the disease has been described since 1896 on <em>P. mugo</em>, and has also been reported on <em>P. radiata </em>and native species, such as <em>P. pinea</em>, <em>P. pinaster</em> and <em>P. halepensis</em>. In North America the fungus was described since 1920, and recently has been reported as an emerging problem in <em>P. strobus</em> plantations in Eastern North America. In 2010 in Spain <em>C. pinea</em> was found on the same stem of a P. radiata tree that was also infected by <em>Fusarium circinatum</em>, an invasive alien pine pathogen introduced in Europe in the early 2000s. Aim of this work was to increase knowledge on this emerging disease, by analyzing the phylogeny of European (E) and North American (NA) pathogen populations, challenging the pathogenicity on different native and non-native hosts, and assessing whether a possible association with <em>F. circinatum</em> exists. European isolates showed no genetic variability and clustered with a single NA provenance. In contrast NA strains are much more variable. <em>C. pinea</em> was able to cause significant lesions on seedlings of different pine species. Contrasting results were obtained as regards of association with <em>F. circinatum</em>: different <em>C. pinea</em> isolates react differently to its presence. The uniformity of the European population suggests an introduction event, probably from North America. It is possible that Caliciopsis canker could become a dangerous pathogen of pine stands in Europe, especially if they suffer for environmental stresses due to climate change. Finally, <em>F. circinatum</em> seems to induce the production of ligninases by some <em>C. pinea</em> strains, suggesting a fungus-fungus interaction.</div>
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