Ridley, G.S., Bain, J., Bulman, L.S., Dick, M.A., & Kay, M.K. 2000 Threats to New Zealand's indigenous forests from exotic pathogens and pests.. Science for Conservation No. 142: 67 pp.
Notes: The principal pathways by which forest pathogens and pests enter New Zealand are in debris inadvertently trapped in cargo (both sea and air) as well as in imported used vehicles. The regions which dominate trade and passenger travel are Australasia and the Northern Hemisphere, and they are also the major sources of contaminants arriving in New Zealand. Details are given of new records of pathogens and pests affecting trees and woody shrubs for the periods 1950-97 (insects) and 1956-97 (fungi). There are no records of invasion of temperate forest pathogens and pests between the Northern and Southern Hemispheres. This is due to the divergent floristic history and biogeography of the continents of the Northern and Southern Hemispheres. New Zealand is biogeographically linked with Australia, South America and Africa, and these are the most likely source of devastating pathogens. Similarly, pest threats will also come from these areas, although widely polyphagous insects from the Northern Hemisphere are also a potential problem. Impact scenarios are developed for various species, including Eriococcus orariensis (manuka (Leptospermum) blight) which failed to become a major pest due to a fungal parasite. The risk to New Zealand's forests was deemed to be medium to high from E. orariensis.