New host and country records of the Dothistroma needle blight pathogens from Europe and Asia

Abstract

Dothistroma needle blight (DNB) is a serious disease of pines (Pinus spp.), with a worldwide distribution. It is caused by the ascomycete fungi Dothistroma septosporum (teleomorph: Mycosphaerella pini) and Dothistroma pini (teleomorph unknown). Recently, DNB was found on Pinus peuce in Austria, Pinus pallasiana in Ukraine and the European part of south-western Russia, as well as on Pinus radiata and Pinus wallichiana in Bhutan. Based on DNA sequence comparisons of the internal transcribed spacer and b-tubulin gene regions, isolates from Austria and Bhutan were identified as D. septosporum, while isolates from Ukraine and south-western Russia were identified as D. pini. Additional isolates studied from Pinus mugo in Hungary confirmed the presence of D. septosporum in this country. The record of D. septosporum on exotic P. peuce in Austria represents a new host report of this needle blight pathogen in Europe. Likewise, DNB and the associated pathogen, D. septosporum are reported from Bhutan, eastern Himalayas, for the first time. In addition, D. pini was found in two European countries and on a new host, P. pallasiana. These European records represent the only reports of D. pini from outside the north-central USA. Morphological examination of selected specimens from different hosts and countries showed that D. septosporum and D. pini overlap in the length of their conidia, while the width is slightly wider in D. pini than in D. septosporum. The differences in conidial width are so small, however, that identification of the two Dothistroma species solely based on morphology is virtually impossible. The new host and country records provided here are consistent with the continuing trend of reports of the DNB pathogens from new hosts and new geographical areas during the last two decades, particularly in the northern hemisphere.

The role of weather and topography in the development of Dothistroma septosporum.

“…It is also consistent with observations from a growing Dothistroma needle blight outbreak on Pinus pallasiana D. Don in southern Ukraine, where the disease is rarely observed on trees growing at low densities on wind-exposed slopes at higher elevations (Barnes et al 2008). This finding supports the suggestion by that 'hot spots' for D. septosporum infection are in areas where cool air can pool, such as in low-lying areas.…”

“…Barnes et al (2004) proposed two species of Dothistroma: Dothistroma septosporum (found worldwide) and Dothistroma pini (found in north central USA, Ukraine, and southwestern Russia). So far DNA sequence comparisons are the most reliable way to conclusively distinguish between the two Dothistroma species (Barnes et al 2008). Until recently D. pini had only been found in north central USA (Barnes et al 2004), but its presence on native pine in Ukraine and southwestern Russia has raised questions as to whether D. pini could have originated from…”

“…It is responsible for extensive damage in exotic plantations in the southern hemisphere in countries such as Chile, Kenya, Australia, and New Zealand (Ivory 1967;Gibson 1972). Reports from the USA, UK, Czech Republic, Austria, Serbia, Ukraine, and the European part of south-western Russia suggest that Dothistroma needle blight is on the rise in the northern hemisphere Taylor and Walla 1999;Bednarova et al 2007;Barnes et al 2008). In the northern hemisphere it is thought to be native to pines (Harrington and Wingfield 1998), and until recently was not considered an important pest.…”

Introduced pathogens found on ornamentals, strawberry and trees in Finland over the past 20 years

“…Furthermore, sequence analysis of the ITS region for a selection of these samples detected only minor differences and revealed that M. hiratsukanum in East Asia and Europe belong to a single palearctic population ). Thus, as proposed earlier by , it seems likely that the natural spread of a new rust species through (Barnes et al 2004), whereas that of D. pini is unknown (Barnes et al 2008). Red band needle blight is caused in Europe mainly by D. septosporum while D. pini has so far been reported here only occasionally (Barnes et al 2007).…”

Managing Florida's Plantation Forests in a Changing Climate

“…worldwide (Bulman et al 2013). In many areas, there have been significant increases in outbreak frequency and the disease has recently expanded into new areas (Barnes et al 2008). Research has implicated strong El Niño Southern Oscillation (ENSO) events coincident with intercontinental disease outbreaks (Woods et al 2016) and suggests that future climate predictions for the Northern Hemisphere will favor Dothistroma needle blight outbreaks in many areas.…”