Sphaeropsis sapinea found as symptomless endophyte in Finland

Abstract

The aim of this study was to determine if the ascomycete fungus Sphaeropsis sapinea (Fr.) Dyko & B. Sutton (syn. Diplodia sapinea (Fr.) Fuckel) could be cultured from surface sterilized Scots pine twigs presenting the endophytic stage of this fungus. This fungus causes the disease called Diplodia tip blight in conifers. Symptoms become visible when trees have been weakened by abiotic stressors related to temperature, drought and hailstorms. The disease is rapidly increasing and is observed regularly in Scots pine (Pinus sylvestris L.) forests in Europe. Changes in climatic conditions will gradually increase the damage of this pathogen, because it is favored by elevated temperatures and additionally the host trees will be more susceptible due to related environmental stress. Diplodia tip blight is emerging towards Northern latitudes, thus, actions to monitor the spread of S. sapinea in pine-dominated forests should be undertaken in Finland. Our aim was to search for S. sapinea in Scots pine along a transect in Finland. Branch samples were collected from healthy Scots pine, fungal endophytes were isolated and morphologically identified. Sixteen S. sapinea strains were found from four Scots pine trees from two locations. This finding confirms that S. sapinea is found as an endophyte in healthy Scots pine in Finland.