Non-destructive measurement of Scots pine heartwood stilbene content and decay resistance by means of UV-excited fluorescence spectroscopy

•A custom-built device was used to measure fluorescence from Scots pine heartwood.•Heartwood fluorescence intensity and stilbene content had a quantitative association.•Fluorescence measurements could be performed on green and dried heartwood.•Stilbene content is a promising variable for predicting heartwood decay resistance.•The method has potential to be utilized in timber grading and tree breeding programs.