First Record of Thyronectria pinicola on Pinus radiata in Australia

Abstract

Neonectria fuckeliana (C. Booth) Castl. & Rossman is the cause of nectria flute canker of exotic Pinus radiata plantations in New Zealand and Chile, where sunken cankers are associated with pruned branch stubs (Dick and Crane 2009; Morales 2009). The bright colored (red), superficial, aggregated perithecia are typical of the Nectriaceae (Hirooka et al. 2012). Nectria flute canker is a key biosecurity threat to Australia’s 1 million ha of exotic Pinus plantations, where annual surveys are conducted over the majority of the estate (Carnegie et al. 2008). During the course of forest health surveys in southeastern New South Wales, Australia, in October 2012, fruiting bodies typical of the Nectriaceae were detected on a dead P. radiata tree near Bombala. Teleomorphic structures were not observed, only anamorphic. Morphological features of the stromata (erumpent, orange to red), pycnidia (aggregated in groups of 3 to 10, superficial, subglobose, cerebriform to slightly cupulate, red to bay), and conidia (hyaline, ellipsoidal to oblong, nonseptate, 2.5 to 3.5 × 1 to 1.5 μm) corresponded to the description of Thyronectria pinicola (Kirschst.) Jaklitsch & Voglmayr (syn. Pleonectria pinicola) (Hirooka et al. 2012; Jaklitsch and Voglmayr 2014). Ascomata were selectively removed from bark with sterile forceps and DNA was extracted using the UltraClean Plant DNA Isolation Kit (MoBio Laboratories, Solana Beach, CA, USA). The internal transcribed spacer (ITS) and large subunit (LSU) regions of nuclear ribosomal DNA were amplified with ITS1F/ITS4 and LROR/LR7 as done by Hirooka et al. (2012). The ITS and LSU sequences were 100% identical to isolates of T. pinicola included in the studies by Hirooka et al. (2012). Specimens DAR 80239 (GenBank Accession Nos. ITS: KP751376, LSU: KP751378) and DAR 80240 (GenBank Accession Nos. ITS: KP751375, LSU: KP751377) were 100% identical to T. pinicola HM484540 (596/596 identities) and JF832615 (460/460 identities) in the ITS region, and 100% identical to HM484567 (801/801 identities) and JF832747 (795/795 identities) in the LSU region. Collections previously assigned to Nectria balsamea are now recognized as three distinct species that correlate to host plants: Thyronectria balsamea (Cooke & Peck) Jaklitsch & Voglmayr on Abies spp.; T. boothii (Hirooka, Rossman & P. Chaverri) Jaklitsch & Voglmayr on Picea spp.; and T. pinicola on Pinus spp. (Hirooka et al. 2012; Jaklitsch and Voglmayr 2014). T. pinicola is known from several Pinus spp. in the Northern Hemisphere, including Germany, Japan, and the USA, while T. balsamea is only known from Abies in North America and T. boothii from Picea in Slovakia (Hirooka et al. 2012). A search of Australian (http://www.planthealthaustralia.com.au) and New Zealand (http://nzfungi2.landcareresearch.co.nz) fungal herbaria indicates no previous records of T. pinicola in either of these countries, nor any nectriacous species on Pinus in Australia. This appears to be the first record of T. pinicola from Oceania, and also from P. radiata, the most important softwood plantation species in temperate regions of the Southern Hemisphere. Further surveys have revealed T. pinicola on fire-damaged and wind-blown P. radiata in several major pine-growing regions in New South Wales. Although T. pinicola is not considered a primary pathogen, this finding illustrates the benefit of forest health surveys in supplementing biosecurity surveys to detect biosecurity threats.