To investigate whether there is a relation between the availability of nitrogen and the incidence of damage caused by the parasitic fungus Sphaeropsis sapinea (Fr.) Dyko & Sutton in Corsican pine (Pinus nigra ssp. laricio (Poir.) Maire) stands, needle and soil samples were taken in 29 stands in spring and early summer of 1986. The infected stands proved to contain higher nitrogen levels in the needle tissue and concomitant higher ammonium levels in the soil. Phosphorus was also present in larger amounts in needle tissue and soil. Most of the additional nitrogen in the needles of the affected stands was stored in free amino acids. Particularly the levels of the nitrogen-rich amino acids asparagine, glutamine, histidine, lysine, and arginine strongly increased. Arginine was by far the most abundant free amino acid in both healthy and infected stands. Also proline showed a remarkable rise in concentration. These results are discussed with regard to other recent Dutch field and greenhouse studies concerning S. sapinea.
