CURBING INTRODUCTIONS OF FOREST INSECTS AND DISEASES ON NURSERY STOCK

Faith T. Campbell

The Nature Conservancy 4245 North Fairfax Dr., Arlington, VA 22203

ABSTRACT

Since the early 1800s, at least 18 highly damaging forest the USDA Animal and Health Inspection Service, insects and diseases have been introduced to the United the North American Plant Protection Organization, The States and its territories via the pathway of trade in International Union of Forest Research Organizations, living . and The Nature Conservancy.Sources for obtaining these Half of these pests (those listed on the right side of Table documents are referenced at the end of the paper.) 1) entered the country in the past 35 years. Worse, 6 of There is also agreement on the reasons for the rising threat: those 10 introductions have been detected since 2000: in recent decades, plant imports have increased greatly, lobate lac scale, Asian scale, Erythrina gall wasp, the geographic range of suppliers has expanded, and more `o`hia rust, cycad blue butterfly, and Pisonia scale. rapid transport allows more pests to survive transit. At the There is widespread agreement that the current same time, phytosanitary safeguards have been relaxed phytosanitary system is not effective in preventing rather than tightened. introductions via the live plant trade. (See statements by

Table 1. Forest pests introduced via the trade in living plants since 1800

- cinnamomi Dogwood anthracnose - Discula destructive blight - Cryphonectria arasitica Sudden Death - White pine blister rust - Cronartium ribicola Bromeliad weevil - Metamasius callizona Balsam woolly adelgid - Adelges piceae longhorned beetle - Anoplophora chinensis Port-Orford-cedar root disease - Lobate lac scale - Paratachardina lobata lobata scale - Cryptococcus fagisuga Pisonia scale - Pulvinaria urbicola European Viburnum leaf beetle - Pyrrhalta viburni Asian cycad scale - Aulacaspsis yasumatsui Hemlock woolly adelgid - Adelges tsugae Erythrina gall wasp - Quadrastichus erythrinae Butternut canker - Sirococcus clavigignenti - `o`hia rust - Puccinia psidii juglandacearum Cycad blue butterfly -Chilades pandava

2007 USDA Interagency Research Forum - GTR-NRS-P-28 9 The U.S. phytosanitary system currently relies largely The NAPPO and IUFRO papers both noted the importance on inspection. When USDA APHIS becomes aware of a of preventing introductions of organisms that have not sufficient risk, it conducts a pest risk assessment of one been thoroughly studied. The history of introductions or a few genera from a particular country. supports the concern: at least six of the most damaging forest pathogens that entered the country on imported plants Both approaches have significant weaknesses. Regarding were unknown to science when they were introduced. inspection, APHIS, NAPPO, and IUFRO agree that These were Cryphonectria parasitica, Phytophthora current trade volumes overwhelm inspection capacity. lateralis, Discula destructive, , The NAPPO Concept Paper notes that inspectors Phytophthora ramorum, and Sirococcus clavigignenti- experience great difficulty in detecting pathogens, small juglandacearum. pests, pests at low densities, pests living inside the plant, or if symptoms are masked by pesticides. International trade rules adopted under the auspices of the World Trade Organization (WTO) and the International Pest risk analysis has several problems. First, it is Plant Protection Convention (IPPC) require that resource intensive. APHIS has admitted that the agency phytosanitary regulations be applied only to pests that have has insufficient funds to complete risk assessments been evaluated by pest risk assessments. The only exception and amend regulations in a timely response to newly is provisional regulations. These risk assessments must perceived threats. evaluate risks with great specificity. Even “pathway” risk Second, and more troubling, risk assessments are assessments must evaluate each pest using the pathway as severely limited in identifying threats. As the NAPPO to its specific likelihood of entry, establishment, or spread. and IUFRO papers have pointed out, risk assessments These rules appear to impede effective exclusion policies based on lists of known quarantine pests do not address by tying regulatory action to the time-consuming and uncertainties arising from scientifically limited risk assessment process. • Organisms not known to science There is widespread agreement on the structure of a long- • An organism’s behavior in its native environment is a term solution to the challenge of preventing introductions poor predictor of its behavior when introduced to a new of organisms that are too poorly known to be evaluated in environment a risk assessment. That solution is to institutionalize clean • Increased risk when the pest or pathogen hybridizes stock or best management practices programs that will An effective exclusion program must prevent minimize the presence not just of quarantine pests (those introductions of pests that are unknown or insufficiently identified through risk assessment) but also most insects, understood, and it must be implemented quickly to curb pathogens, and other potential pests that have not been the current, unacceptable rate of introductions. evaluated. The IUFRO panel suggests that adoption by

Table 2. USDA APHIS chart showing changes in plant import conditions since the “Q-37” regulations were first adoptedd

Trading Partners Europe Worldwide

# of Items Allowed Import Limited (< 100 items) germplasm of clonal Unlimited material only

Fumigation Mandatory on all imported stock Only when quarantine pest found

Likely Purpose of Importation Nursery propagation program “starter” Direct field/homeowner planting material Immediate distribution Slow distribution

10 2007 USDA Interagency Research Forum - GTR-NRS-P-28 the IPPC parties of an international standard (modeled (1) Publicly adopt a goal of providing a much higher level after the international standard on wood packaging) of protection. APHIS should state its intention of cutting would allow clean stock programs to apply to the full the rate of introduction via this pathway to one-tenth of its range of pests, not just quarantine pests. As its rationale, apparent current level—from 10 over 30 years to the IUFRO panel notes that the living plant pathway only 1. has been the means by which many pests have been introduced—just as wood packaging has been. This (2) By the end of 2007, establish a strong NAPPRA parallel situation justifies a similar response: reliance on category and put into that category nearly all whole plants a pathway approach that departs from the usual blacklist and cuttings. APHIS could allow imports of these plant approach. taxa under any of the following conditions: • plants imported in the form of tissue culture or seed This proposal has great promise—particularly because • plants imported into a secure containment facility and an IPPC expert group is already exploring whether to held for a sufficiently long period to ensure they are recommend an international standard for living plant pest- and disease-free movement. However, it is not certain that the IPPC • plants imported from a third-party certified clean stock parties will accept such a broad standard. program. In any case, negotiating and implementing effective (3) Apply a transparent process to determine which taxa/ clean stock programs will require several years. We type/origin combinations are sufficiently unlikely to need stringent measures to curtail introductions now to transport pests that they can be removed safely from protect our forests until IPPC parties can negotiate and NAPPRA. implement a comprehensive program. (4) Focus its risk assessments on the most likely USDA APHIS has proposed the solution: placing plants introductory pathways, which would be defined, such as suspected of carrying pests temporarily into a limbo bare-rooted plants from East Asia. category pending further evaluation and development (5) APHIS and its stakeholders should work together to of effective phytosanitary barriers. APHIS could do this secure substantially more staff and funding to enable the quickly. Because plants are placed in limbo on an interim agency to undertake risk analyses and amendments to its or “provisional” basis, APHIS would not be required regulations in a timely manner. to complete a pest risk analysis on each plant/origin combination before acting. Sources of further information: APHIS Whitepaper (December 2005) http://www. Unfortunately, APHIS intends to phase in the limbo aphis.usda.gov/import_export/plants/plant_imports/ category. Initially, only the few plant host/origin downloads/q37_whitepaper.pdf combinations that transport known quarantine pests (If the link doesn’t work, try using your favorite search would be included and even then only when the plants in engine to search for “Addressing the Risks Associated question have not previously been imported into the U.S. with the Importation of Plants for Planting”) Only after several years might APHIS expand the category NAPPO Plants for Planting Concept Paper--attached to address pests whose existence is unknown or whose to RSPM 24 at http:/www.nappo.org/Standards/NEW/ ecological role in their native and introduced ranges has RSPMNo24-e.pdf not been adequately assessed. IUFRO Working Party on Alien Pest Movement in International Trade The Nature Conservancy believes that APHIS should apply its conception of a limbo category more Accessible on www.forestresearch.gov.uk/iufroinvasives aggressively, given the recent rush of introductions. The The Nature Conservancy. An Ounce of Prevention: How Conservancy proposes that APHIS take the following to Stop Invasive Insects and Diseases from Destroying steps: U.S. Forests, [email protected]

2007 USDA Interagency Research Forum - GTR-NRS-P-28 11