Needle fungi and tree health of Pinus radiata in Tasmania

Pinus radiata is one of the most important species of forestry plantation worldwide and many pests and diseases have followed the expansion of this species around the globe. Tasmanian P. radiata plantations suffer from a needle cast disease referred to as spring needle cast (SNC) which has similar symptoms to Cyclaneusma needle cast, a serious disease in New Zealand. Stands with moderate or severe SNC can be expected to suffer potential losses in clear-fall volume. The aetiology of SNC is poorly understood and has long been a point of debate between Tasmania and New Zealand foresters with the New Zealanders attributing SNC to Cyclaneusma minus. Tasmanian research in the 90s proposed that SNC is caused by one or a suite of fungi that are triggered by an unknown environmental stress. Three species of fungi have been putatively associated with SNC, i.e. Lophodermium pinastri, Strasseria geniculata and C. minus. Understanding endophyte diversity is crucial for determining their role in forest health. Endophytes are increasingly recognized for having a role in plant-pathogen interactions leading to disease. In particular, they may play an important role in determining the presence of a disease such as SNC, which does not appear to have a single pathogenic causal agent and which may be associated with environmental stress. The main objective of this study was therefore to identify needle fungal communities which are associated with both healthy and SNC-affected trees in P. radiata plantations in Tasmania. Needle fungi have been extensively studied in conifers but rarely in P. radiata.