Patterns of Dothistroma septosporum conidial dispersal in Colombian Pinus tecunumanii plantations

Dothistroma needle blight (DNB) caused by Dothistroma septosporum is one of the most important needle diseases of Pinus spp., especially in Southern Hemisphere plantations. In Colombia, the pathogen has caused severe outbreaks in plantations of Pinus tecunumanii of the low elevation population (LE). Currently, management strategies suffer from a lack of knowledge regarding the epidemiology of D. septosporum under tropical climatic conditions. In this study we determined the patterns of conidial dispersal and considered how climatic conditions in Colombia influence them. The study was conducted over 15 consecutive months between October 2010 and December 2011 using glass slide-based spore traps. Conidia were found on the traps throughout the year, with the peak abundance during November to January (2010) and November to December (2011). During peak conidial production, relative humidity and temperature had the greatest influence on conidial dispersal. Favourable weather conditions in Colombia, particularly rainfall, have contributed to continuous conidial production throughout the year, leading to D. septosporum infections all year round. This high reproductive rate as a consequence of high precipitation is in contrast to other Southern Hemisphere and Northern Hemisphere countries with more specific periods of rainfall and infection.