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Sudden Oak Death: Science, management, and regulatory challengesSue Cohen and Jonathan Jones, USDA-APHISIntroductionDeveloping a consistent and sound science-based regulatory program for Sudden Oak Death in the USA presents many challenges. Many of these challenges occurred because the fungal pathogen, Phytophthora ramorum, responsible for the Sudden Oak Death disease has only recently been identified and described. A lack of scientific data on the identity, biology, epidemiology, transmission and pathway movement of this pathogen contributed to the difficulties of developing a comprehensive regulatory program. Table 1. A successful Sudden Oak Death regulatory program is based on sound scientific research.
Science, Management, and Regulatory ChallengesInitially, the first and foremost challenge was to confirm the identity of the fungal pathogen responsible for the disease. Then the agency (*) analyzed the risk to determine if this pathogen should be considered an organism that required a regulatory responseprogram. Once it was determined to be an organism requiring quarantine, the list of hosts susceptible to the disease needed to be determined. Finally given the list of susceptible host plants, the possible geographical distribution in the USA and Europe could be determined and also the possible pathways for movement. Each of these steps required intensive review of the science and coordinated efforts of a number of people within and outside of the agency to complete. Initially there were no answers to each of these questions, thereby complicating and lengthening the regulatory effort. Determining when to regulate each potential plant host is a major challenge. Currently, the host status is dependent on completion of traditional Koch's postulates and communication of that research to regulatory officials for review and appropriate action. For foliar hosts such as rhododendron and Bay laurel, fungal cultures are easily isolated from infected leaf tissue plated on selective media. However, fungal cultures from hosts such as oaks, where the disease is expressed in the trunk, are not so easily isolated. Confirmation of host status also requires re-inoculation of plant hosts with pure fungal cultures and expression of the disease symptoms with re-isolation. This makes it difficult to complete Koch's postulates. Often, molecular tools are designed for the laboratory research environment and must be adapted and validated for regulatory use. So, another challenge was validating a molecular tool for pathogen identification, detection and survey suitable for regulatory activities. Other challenges included the national pilot survey protocols such as detection tools and risk-based sampling designs. Standards had to be set for the level of evidence required for regulatory changes. New research information that could affect regulatory policy was constantly being announced about the biology and pathways of movement of the pathogen. Lastly, the lack of available scientific information on P. ramorum increased the uncertainty surrounding the potential risks of entry, spread, and impacts posed by this pathogen. A number of Sudden Oak Death risk assessments at the state and country levels were written. They were based on the few scientific studies available, on extrapolation from studies completed on other Phytophthora species and on preliminary data/personal communications. The lack of available scientific data contributes to uncertainty concerning the risk ratings in the current pest risk assessments and when deciding on which articles (plants, plant parts, products, soil, etc.) to regulate, and what pathways to regulate. Further scientific studies on dispersal, transmission, and epidemiology of P. ramorum would increase the level of certainty and allow regulatory agencies to make their programs more focused. Better information on the volumes, types of products, and trade routes are also necessary for developing a successful regulatory program for Sudden Oak Death.
Designing A Successful Sudden Oak Death Regulatory ProgramA solid regulatory program can effectively slow the spread of P. ramorum and prevent new introductions. As stated in 7 CFR Part 371.3, Plant Protection and Quarantine (PPQ) (*agency), a part of the Animal and Plant Health Inspection Service under the United States Department of Agriculture, "protects and safeguards the Nation's plant resources through programs and activities to prevent the introduction and spread of plant pests and diseases." Further, PPQ has the authority for "Developing of regulations (including quarantines) regarding noxious weeds and plant pests and diseases." For brevity, in this paper "plant pests and diseases" will be referred to as "pests". The first quote concentrates on two concepts, "preventing the introduction and spread". PPQ's goal is to prevent certain pests from entering the country, such as Mediterranean fruit fly (insect), exotic cuscutas (weed), and orange sweet scab (plant disease). PPQ has established quarantines and regulations designed to prevent these from entering the country. When a harmful pest enters the country and becomes established, PPQ may start a program designed to prevent the spread of that pest, including eradication or a control program. Eradication programs are designed to delimit and eliminate the pest. Control programs are designed to slow the artificial spread and manage the pest. Usually the regulated areas expand year-to-year as either the pest expands in natural range or is introduced and established in new areas. Examples of current eradication programs include citrus canker (Florida) and Asian longhorned beetle (NY and IL). Examples of control programs are gypsy moth, pine shoot beetle, and Phytophthora ramorum. All of APHIS quarantines and programs are based on the best available science. For gypsy moth there is over 100 years of research to draw upon and little controversy associated with the program. In contrast, Phytophthora ramorum was only recently named, late in 2001. Scientific knowledge about this pest is relatively limited but rapidly evolving. The limited available science about this pest makes regulating this pest a challenge. In the current control programs for P. ramorum, PPQ has identified the potential pathways and taken the appropriate level of regulatory action. These regulatory actions were published in the Federal Register 14 February 2002 as 7 CFR 301.92 as an interim rule and in four policy letters signed by PPQ's Deputy Administrator. These can be read in detail via links at www.aphis.usda.gov/ppq/ispm/sod and are summarized in the chart below: Table 2. Articles and Actions listed in the APHIS Sudden Oak Death interim rule (published 14 February 2002)
Further, PPQ has notified the European Union of similar restrictions put in place for exports to the United States effective 1 November 2002 (regulations still in the process of being published as of this date). To assure the validity of APHIS regulations and maintain foreign markets, the US is conducting surveys in States of nurseries and natural areas. Results thus far are negative outside the currently regulated areas. References
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