The aggressiveness of Sphaeropsis sapinea on Austrian pine varies with isolate group and site of infection

Summary The aggressiveness of the A and B isolate groups (morphotypes) of Sphaeropsis sapinea on shoot tips and lower stems of Austrian pine ( Pinus nigra ) was compared. The distinct differences in aggressiveness between the two S. sapinea groups, previously reported for other conifers, are confirmed for Austrian pine. However, the relative aggressiveness of the B group isolate varied by site of infection. Although the B group isolate of S. sapinea was not aggressive on shoot tips of Austrian pine, it was aggressive on stems of this host.