Spring needle cast (SNC) in Tasmania is defined by the early casting of pine needles and appears in 6-to 7-year-old pine plantations after canopy closure. The severity of SNC can vary significantly among trees growing within the same plantation. Fungal communities were surveyed in a Pinus radiata family trial, using DNA extraction from needles, PCR with fungal-specific primers and sequencing to detect the presence of fungal species. Samples were taken at the same time as the trees were scored for disease severity. Trees with contrasting levels of SNC disease severity have significantly different needle fungal communities, but family pedigree and different ages of needle are not clearly distinguished by their fungal communities. All common fungal pathogens previously implicated in causing SNC were identified from the study, but of these, only Lophodermium pinastri was correlated with high levels of disease. Several species of Teratosphaeriaceae were detected, and one of these was also strongly associated with needle cast.

Summary Cyclaneusma Needle Cast is associated with the fungal pathogen Cyclaneusma minus. The disease has led to significant losses of Pinus radiata production in New Zealand, but the disease appears less serious in Australia. Two cultural morphotypes of C. minus have been discriminated in New Zealand, and isolates from Australia also correspond to these two morphotypes. To examine if the two morphotypes of Cyclaneusma are different species, phylogenetic analysis using sequences from five gene regions (rDNA ITS, mt‐LSU, n‐LSU, tef–1 and βT‐1) was conducted. This study revealed that C. minus consists of two distinct clades which correspond to the two morphotypes. One morphotype (‘verum’) was more closely related to Cyclaneusma niveum than to the other morphotype (‘simile’). A morphological description is required to formalise the new species represented by the ‘simile’ clade; an investigation of the individual pathogenic behaviours of both morphotypes is also required.

Background: Needle fungi in conifers have been extensively studied to explore their diversity, but environmental factors influencing the composition of fungal communities in Pinus radiata D.Don needles have received little attention. This study was conducted to examine the influence of the environment as defined by rainfall, elevation and temperature on the composition of fungal communities in pine needles at an age prior to that at which spring needle cast (SNC) is generally observed. Elucidating the entire fungal community in the needles is a first step towards understanding the cause of the disease. Methods: Needle samples were collected from 5-year-old P. radiata trees, their age predating the onset of SNC, from 12 plantations in Tasmania. Interpolated data for the climate variables, including seasonal components for rainfall and temperature, were obtained from an enhanced climate data bank. Pooled needle samples were examined for the fungi they contained using DNA sequencing of cloned polymerase chain reaction (PCR) products. Clones were grouped into operational taxonomic units (OTUs) and identified to their lowest possible taxonomic level by comparison with reference isolates and public DNA databases. Results: DNA sequencing revealed that needle fungal communities differed greatly, depending upon the total annual rainfall and needle age. Needle fungi that have been previously associated with pathogenic behaviour, such as Cyclaneusma minus, Dothistroma septosporum, Lophodermium pinastri, Strasseria geniculata and Sydowia polyspora, were all found in the needles in this study. Also, of 70 ascomycetous OTUs that were discriminated by their DNA sequences, 21 were identified as belonging to the Teratosphaeriaceae. Conclusions: An overview of the endophytic fungi present in the needles of P. radiata has been obtained from trees whose age precedes the onset of SNC. All of the previously known pathogenic species for needle cast diseases were present, in addition to a range of unidentified OTUs belonging to the Teratosphaeriaceae.

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