Background/Question/Methods Sudden Oak Death (SOD), caused by
Phytophthora ramorum, is an invasive forest disease that was recently discovered in
Oregon (2001), where it has infected at least 170 acres and caused mortality in tanoak as well as leaf and shoot blight in many other hosts. We performed tradeoff analyses of policies being implemented to control the spread of SOD in order to provide a context to policy makers and to improve the allocation of resources invested in control. Results/Conclusions
P. ramorum is currently distributed within a 162 square mile quarantine area in SW Oregon, where 1400 acres have been treated to limit SOD spread through eradication of host plants, at a total direct cost of $2 million. The disease has also been discovered at 55 nurseries in Oregon (as of 2005), likely causing an additional $727,100 in direst losses to the nurseries. Impacts to Oregon forests through tree mortality are thought to be limited to the tanoak forests in SW Oregon, where tanoaks are easily replaced ecologically by other hardwoods. Commercial forest landowners actively replace tanoak with conifers due to the low economic value of tanoak. Therefore, the major economic impacts of SOD to Oregon will come not from ecological losses, but instead from state, national, and international quarantines that control the treatment, movement, and export of P. ramorum hosts and their products, such as trees and lumber, floral greens, nursery plants, and Christmas trees. These policies would increase production costs and limit market access for affected commercial producers. The best size for a quarantine zone involves trading off between the benefits of a larger zone—for example, a lower chance of spread beyond the zone—with the costs of a larger zone—such as, increased numbers of businesses within the zone, higher enforcement/monitoring costs, lower effectiveness of enforcement, and spread within the quarantine zone. Similarly, a preliminary tradeoff analysis of a California host reduction zone to stop the northward spread of SOD indicates the level of avoided costs necessary to make the current zone size and investment worthwhile.
