Abstract:
European forests are threatened by increasing numbers of invasive pests and pathogens. Over the past century,
Lecanosticta acicola, a foliar pathogen predominantly of Pinus spp., has expanded its range globally, and is
increasing in impact. Lecanosticta acicola causes brown spot needle blight, resulting in premature defoliation,
reduced growth, and mortality in some hosts. Originating from southern regions of North American, it devastated
forests in the USA’s southern states in the early twentieth century, and in 1942 was discovered in Spain.
Derived from Euphresco project ‘Brownspotrisk,’ this study aimed to establish the current distribution of
Lecanosticta species, and assess the risks of L. acicola to European forests. Pathogen reports from the literature,
and new/ unpublished survey data were combined into an open-access geo-database (http://www.portaloff
orestpathology.com), and used to visualise the pathogen’s range, infer its climatic tolerance, and update its
host range. Lecanosticta species have now been recorded in 44 countries, mostly in the northern hemisphere. The
type species, L. acicola, has increased its range in recent years, and is present in 24 out of the 26 European
countries where data were available. Other species of Lecanosticta are largely restricted to Mexico and Central
America, and recently Colombia.
The geo-database records demonstrate that L. acicola tolerates a wide range of climates across the northern
hemisphere, and indicate its potential to colonise Pinus spp. forests across large swathes of the Europe. Preliminary
analyses suggest L. acicola could affect 62% of global Pinus species area by the end of this century, under
climate change predictions.
Although its host range appears slightly narrower than the similar Dothistroma species, Lecanosticta species
were recorded on 70 host taxa, mostly Pinus spp., but including, Cedrus and Picea spp. Twenty-three, including
species of critical ecological, environmental and economic significance in Europe, are highly susceptible to
L. acicola, suffering heavy defoliation and sometimes mortality. Variation in apparent susceptibility between
reports could reflect variation between regions in the hosts’ genetic make-up, but could also reflect the significant
variation in L. acicola populations and lineages found across Europe. This study served to highlight significant
gaps in our understanding of the pathogen’s behaviour.
Lecanosticta acicola has recently been downgraded from an A1 quarantine pest to a regulated non quarantine
pathogen, and is now widely distributed across Europe. With a need to consider disease management, this study
also explored global BSNB strategies, and used Case Studies to summarise the tactics employed to date in Europe.
