The future of exotic plantation forestry in the tropics and southern hemisphere : lessons from pitch canker : evidence for sustainable plantation forestry

Abstract

Exotic plantation forestry, particularly with Pinus and Eucalyptus species in the tropics and southern Hemisphere, has expanded dramatically during the course of the last Century. Success of these intensively managed plantations is largely attributed to the fact that trees have been separated from their natural enemies. Due to increasing rates of introduction of pests and pathogens, this is a situation that is changing relatively rapidly. There is also growing evidence that unexpected native pests and pathogens are developing the capacity to infect exotic plantation trees. Clearly, highly productive, and intensively managed fibre farms are threatened and their future is likely to be more complicated than it has been in the past. The appearance of the pitch canker pathogen, Fusarium circinatum in South Africa, provides a contemporary example of new problems relating to a pathogen, previously absent from a country. This pathogen was first found in a single nursery and it has rapidly spread to all South African pine nurseries. It has significantly complicated pine propagation and is resulting in substantial losses in plantation establishment. Whether the fungus will manifest itself as a pathogen of adult trees as is the case elsewhere, is unknown. But this prospect is a matter of serious concern. Research aimed at a better understanding of the biology of F. circinatum in South Africa is essential. Furthermore, development of disease tolerant planting stock, in advance of a potentially deteriorating situation, would appear to be crucially important.


Southern African Forestry Journal No.195 2002: 79-82