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Photo by Forest & Kim Starr
By Kimberly Burnett and Christopher Wada
Since its first documented introduction to Hawai‘i in 2005, the rust fungus Puccinia psidii has already severely damaged Syzygium jambos (Indian rose apple) trees and the federally endangered Eugenia koolauensis (nioi). Fortunately, the particular strain has yet to cause serious damage to Metrosideros polymorpha (‘ōhi‘a), which comprises roughly 80% of the state’s native forests and covers 400,000 ha. Although the rust has affected less than 5% of Hawaii’s ‘ōhi‘a trees thus far, the introduction of other diseases, more virulent strains, and the genetic evolution of the current strain are still possible (in particular, Ceratocystis fimbriata Rapid ‘Ōhi‘a Death) now threatens the species since its detection in 2014). Since the primary pathway of introduction is Myrtaceae plant material imported from outside the state, potential further damage to ‘ōhi‘a can be minimized by regulating those high-risk imports. Starting in August 2007, a one-year interim rule prohibited the importation of Myrtaceae plants or parts from infected areas (South America, California, and Florida) with the exception of treated seeds and tissue cultures certified to be free of P. psidii. After the rule expired in August 2008, Myrtaceae import restrictions were relaxed. By 2011, however, HDOA judged that there was adequate scientific justification to support a permanent Myrtaceae import rule to deter the arrival and establishment of new genetic strains of P. psidii.
In an article published in Environmental Science and Policy (Burnett et al., 2012), UHERO researchers in collaboration with Lloyd Loope from USGS examined the potential economic impact on the state’s florist, nursery, and forest plantation industries of a proposed rule that would ban the import of non-seed Myrtaceae plant material and require a 1-year quarantine of seeds. A phone survey of florists (205 respondents) and nurseries (168 respondents) across the state was conducted between August and December 2010. Survey results suggested that less than 35% of florists on each island regularly stock Myrtaceae (Eucalyptus, Myrtle, or Waxflower), and nearly all agreed that beyond a potential transition period during which buying practices would need to be adjusted to ensure the availability of Myrtaceae alternatives for filler material, there would likely be no significant lasting economic impacts of an import ban. Nurseries similarly did not expect large impacts; 20% or fewer nurseries on each island sold Myrtaceae, and an import ban would prevent both damages to the current stock of local Myrtaceae and mitigative costs that nurseries would face if a successful P. psidii invasion were to occur. Discussions with two property managers also suggested that the perceived costs of the import ban to industrial plantations were fairly low and that plantations, like nurseries, would benefit from prevention of a successful invasion.
Taking into account costs to florists (time spent finding Myrtaceae alternatives and lost sales during the transition period) and benefits to plantation owners (avoided loss in Eucalyptus yield and profits assuming the end product is biofuel) of a potential P. psidii invasion, our analysis suggested that the net benefit of an import ban is positive for a wide range of assumptions, even without accounting for the benefits of ‘ōhi‘a protection and avoided mitigation costs to nurseries. The benefit-cost ratio is likely even larger today, given the increasing scarcity of ‘ōhi‘a due to Rapid ‘Ōhi‘a Death. With both scientific and economic justification, Gov. David Ige and the Hawaii Board of Agriculture recently approved an amendment to HAR Chapter 4-70 to include Subchapter 15, imposing restrictions on the importation of Myrtaceae. Effective May 15, 2020, introduction of any Myrtaceae plant, plant part, or seed into Hawai‘i is prohibited, with the exception of dried, non-living plant materials; seeds, with no other plant fragments, that have been surface sterilized using an approved treatment; tissue cultured plants grown in sterile media and in a completely enclosed sterile glass flask or other similar container; or by approved permit.
Burnett, K.M., S. D’Evelyn, L. Loope, and C.A. Wada. 2012. An Economic Approach to Assessing Import Policies Designed to Prevent the Arrival of Invasive Species: The Case of Puccinia psidii in Hawai‘i. Environmental Science & Policy 19-20: 158-168, https://doi.org/10.1016/j.envsci.2012.03.006