Direct comparisons between phloem reaction development after low density inoculations (three inoculations per fungal species in each tree) and fungus pathogenicity after mass inoculations (400 inoculations per m² of a given fungus per tree), in Norway spruce (Picea abies) inoculated with various blue stain fungal species (adapted from Krokene and Solheim, 1999). Values with the same letter did not differ significantly.