Brown-spot disease is a needle blight of conifers caused by the fungal pathogen Lecanosticta acicola (LA).

Screening of available literature revealed numerous gaps in knowledge, which impede both curative and preventive strategies. Effects of climate change on disease occurrence, the possibility of emergence of more aggressive strains, its biology and dissemination (also including anthropogenic activities) are some of the main questions that need to be addressed. In order to collect data on outbreaks of LA, a global database was established containing information on 3012 observations (879 records of these are officially confirmed by the National Plant Protection Organizations) from 44 countries. This database provides useful information for the (ongoing) modelling of the spread of LA. A global population genetic study conducted within the project showed that the pathogen was likely imported from North America in two major ingressions.

Nothing is known on the impact of eight species of Lecanosticta that are morphologically similar to LA, that were recently described from Central America but not yet recorded in Europe. LA European outbreaks indicate that climate change favours the spread and establishment of the fungus into new areas, in particular where temperatures and summer precipitation increased. On the contrary, dry and hot summers probably limit the spread of LA. As shown by a study conducted by project partners on pines in bogs, infection foci are predominantly located in vicinity of places of human activities indicating a spread caused by humans. Human activities in touristic hot-spots are observed also as a hot-spot for the brown-spot disease and its spread, as is reported by project partners.

Hygienic measures combined with increasing efforts to track outbreaks in early stages and removal of infected trees are the options to protect European forests as well as for urban sites. Inspection of nursery stocks by trained personnel followed by laboratory analyses and the destruction of infested plants are of foremost importance.

Preventing further unintended spread using a system implemented in Slovenia, where pines are preferably removed from sites that experience high touristic pressure is an option also for other countries. For infested bogs, preventing public access may limit the spread of the fungus by visitors and the need to close these sites is in discussion in Austria.

Artificial regeneration of trees should be done by using disease-free stocks only, sourcing high quality seedlings, planting trees at low density, and preferring planting sites where conditions are less favourable to LA such as good drained and aeriated sites.