ASSOCIATION OF SPHAEROPSIS-SAPINEA WITH INSECT INFESTATION FOLLOWING HAIL DAMAGE OF PINUS-RADIATA

Following a hail storm in the southern Cape province of South Africa, about 2000 ha of Pinus radiata plantations suffered die-back associate d with Sphaeropsis sapinea. A series of sample plots in these plantati ons yielded information on the association of trees infected by S. sap inea with colonisation of tissue by two species of cambiophagous insec t pests. The infestation of diseased trees, first by Pissodes nemorens is and then by Orthotomicus erosus, mostly coincided with the zone of tissue discolouration associated with S. sapinea. Pissodes nemorensis proved to be more common than O. erosus and demonstrated the ability t o infest healthy tissue adjacent to discoloured areas colonised by S. sapinea. It therefore displayed the potential to facilitate the furthe r colonisation of healthy cambial tissue by S. sapinea and thus exacer bate die-back of trees.