DETECTION OF NEW INSECTS AND DISEASES IN INDIGENOUS FORESTS IN NEW ZEALAND

The prime objective of forest health surveillance, as defined in this paper, is the early detection of introduced insects and pathogens in order to minimise damage, enhance the possibility of eradication, and limit the cost of control. Since the introduction of systematic surveillance in New Zealand the emphasis has been on protecting plantation forests and little has been done in indigenous forests. The Department of Conservation has not yet taken steps to address this apparent imbalance. The cost of a comprehensive surveillance programme for New Zealand's indigenous forests is estimated at $4.5 million, compared with current costs of $2.4 million for control of fire, $2.3 million for weeds, and $5.8 million for wild animals. There are differences between plantation and protected indigenous forests which might influence susceptibility to, or seriousness of, introduced insects or pathogens, and various factors will need to be considered in developing a forest health surveillance strategy