Dothistroma needle blight : an emerging epidemic caused by Dothistroma septosporum in Colombia

Abstract

Plantation forestry in Colombia is based mainly on non-native species of Pinus and Eucalyptus. Since 2008, a disease with symptoms similar to those of Dothistroma needle blight (DNB) have been found affecting large areas planted to Pinus spp. The aim of this study was to identify the causal pathogen as well as to document the levels of disease incidence and severity. Isolates from each of three forestry zones, collected from different host species, were compared based on rDNA sequence of the ITS regions. These were conclusively identified as Dothistroma septosporum, one of two Dothistroma spp. known to cause DNB. Susceptibility was greatest on low elevation P. tecunumanii followed by P. kesiya and P. oocarpa. Pinus maximinoi and high elevation P. tecunumanii showed tolerance to D. septosporum. The disease incidence in the different zones varied significantly with the Northern zone being the most severely affected. This constitutes the first report of disease distribution and susceptibility of hosts, as well as the first consideration of the relative importance of D. septosporum in Colombia.