November 2018 – Center for Invasive Species Prevention

Comments on EAB deregulation show costs would be too high

Kelly Church (Grand Traverse Band Ottawa Chippewa) with baskets she wove from black ash

As you know, in September APHIS published a proposal to alter management of the emerald ash borer (EAB). Under the proposal, APHIS would no longer regulate movement of firewood, nursery stock, or other items that can transport EAB to new areas. Instead, APHIS proposed to rely on biological control to reduce impacts and – possibly – slow EAB’s spread. I have posted two blogs about the weaknesses of the underlying analysis and the decision by the Center for Invasive Species Prevention to oppose the proposal. The proposal, accompanying “regulatory flexibility analysis,” and 150 comments by the public are posted here.

The Don’t Move Firewood program has provided links to the individual organizations’ comments here.

Here I summarize major points made by those commenting on the proposal.

Most state agriculture departments accepted the proposal. Few commented at all, leaving that to the National Plant Board. The NPB letter consisted of only four paragraphs. In contrast, several state forestry agencies commented.

Several organizations, including the National Plant Board and AmericanHort, agreed with APHIS that the quarantine has not worked primarily because detection tools are so poor. As a result, EAB is able to firmly establish for several years and spread in a new area before authorities detect it and take action.

It is clear from the comments that deregulating EAB might save APHIS money and effort, but the action will exacerbate the already substantial burden on many other U.S. entities – ranging from federal agencies such as USDA Forest Service and National Park Service to homeowners; woodlot owners to (potentially) exporters of all sorts of products; to Native Americans. The economic components of this potential burden surely deserve more serious evaluation as required under several Executive orders.

Comments Categorized

1) The quarantine has slowed the spread of EAB and it remains valuable in granting communities time to prepare

Several of the commenters wished to counter the proposal’s inference that quarantines had failed; rather, they insisted that quarantine has slowed spread of the EAB and that this strategy is still valuable because it gives un-infested areas more time to prepare. Those voicing this view included the National Association of State Foresters; Maine Department of Agriculture, Conservation and Forestry; Montana Department of Natural Resources and Conservation; Fond du Lac Band of Lake Superior Chippewa in Wisconsin; several bands of Native Americans in Maine (Houlton Band, Penobscot, an individual member of the Penobscot); The Nature Conservancy; a man who is both park superintendent for the City of Kalispell, Montana and Chair of the Montana Urban and Community Forestry Association; three local conservancies in Oregon (West Multnomah Soil and Water Conservation District; Four-County Cooperative Weed Management Area from Clackamas, Clark, Multnomah and Washington counties in the greater Portland Metro area; Tualatin Soil and Water Conservation District); Jefferson County Colorado Invasive Species Management team; Maine Mountain Collaborative; Blue Hill Heritage Trust of Maine; a small woodland owner in Maine; and a Professor in the School of Forest Resources at the University of Maine.

Oregon’s Department of Environmental Quality Water Quality Division opposed the APHIS proposal. The Division noted that EAB spread in the east was facilitated greatly by the continuity of ash habitats whereas ash habitats are much more patchy in the West. Given this situation, human transport is the most likely means by which EAB will reach the West – either from infested portions of the U.S. or via trans-Pacific trade.

A few entities that supported APHIS’ proposal – e.g., the Southern Group of State Foresters and – in a separate letter – Texas Forest Service – also said the quarantine had been helpful.

As The Nature Conservancy said in its comments, the quarantine effectively limits two of the most important pathways, firewood and nursery stock. The result has been to protect much of the country from the pest and buying time to develop mitigation measures.

2) APHIS’ dismissal of quarantine is a worrying message (see also discussion of firewood below)

Several of the commenters expressed concern that APHIS too curtly dismissed the value of quarantine – both as it functioned to slow spread of EAB and as a tool used against a wide range of pests. Commenters raising issues about the proposal’s apparent undermining of quarantine as a strategy included the Kansas Forest Service; Maine Department of Agriculture, Conservation and Forestry; Vermont Agency of Agriculture, Food and Markets and the Department of Forests, Parks, and Recreation; and Wisconsin Department of Natural Resources Division of Forestry. The Vermont and Wisconsin agencies asked APHIS to clarify to affected parties what it expects to achieve by the proposed deregulation. The Fond du Lac Band of Chippewa warned that the public might interpret the dropping of regulations as signaling that EAB is no longer important.

Five organizations unified under the banner of the Coalition Against Forest Pests noted that APHIS had set a precedent of dropping regulations when quarantines appear to fail.

A subset of these comments focused on a lack of clarity by APHIS as to its future strategy.

Several commenters said that APHIS had not outlined a coherent strategy for the future. The Kansas Forest Service even called the proposal an agency “exit strategy” rather than a coherent plan. Others raising this issue included the Maine Department of Agriculture, Conservation and Forestry; South Dakota Department of Agriculture and Department of Game, Fish and Parks; and the Coalition Against Forest Pests. Maine noted that the proposal would shift the burden of regulation to the states. Maine and South Dakota said that APHIS, as the responsible federal regulatory agency, should provide a clear and consistent process for regulation of potentially infested products across state lines.

The Tennessee Forest Health Coordinator called for an analysis of EAB program successes that might point to ways in which APHIS could support alternative strategies. A professor of forestry in Maine said APHIS should evaluate and assess techniques specifically to optimize the effectiveness of education and outreach.

Among entities which supported APHIS’ proposed new approach, the Southern Group of State Foresters, Texas Forest Service, and two Vermont agencies – Agency of Agriculture, Food and Markets and the Department of Forests, Parks, and Recreation – urged APHIS to champion a national, multi-agency approach to managing EAB, including creation of a national, voluntary treatment standard and label for firewood; redirecting all savings to research & management – including state surveys. These groups also advocated funding increases for APHIS, the USDA Forest Service, and state EAB programs; and support for states to carry out their enlarged responsibilities for survey, outreach, education, and assistance to affected parties.

The Vermont agencies wrote that EAB “is a nationally significant pest, … which warrants a significant federal role.” Because EAB impacts on communities, forest health, and the forest economy continue to expand, a decision to discontinue regulatory activities should be accompanied by increased federal support for research and management.

The National Association of State Foresters also called for APHIS to champion a national, multi-agency approach, with a somewhat longer list of components. These should include support state research and management efforts, the biocontrol program, identifying genetic strains of ash trees that are resistant to EAB, maintain national treatment criteria for wood products (including firewood), and reconvene the National Firewood Task Force. NASF also urged the USDA Forest Service to develop a cooperative management program to sustain and replace ash trees killed by EAB.

Dr. David Orwig of Harvard Forest also called for funding not just biocontrol but also research areas like silviculture, chemical control, ash utilization, and management guidelines.

This pattern of asking for continued or expanded federal engagement – beyond biocontrol – is quite apparent. Some entitites that said they supported APHIS’ proposal nevertheless called for the agency to continue detection and response components of the program – expressly contrary to the proposal itself.

Thus, AmericanHort, the two Vermont agencies, Wisconsin Department of Natural Resources Division of Forestry, and two Maine departments called for APHIS to continue or increase its engagement in EAB detection and other management activities – including biocontrol, outreach to explain the change in strategy, and engaging the National Park Service and Forest Service in promulgating a consistent firewood policy.

Others who asked for similar commitments were straightforward in opposing the proposal. Thus the North Dakota Department of Agriculture and North Dakota Forest Service – in separate letters – asked that APHIS continue to provide resources to help states monitor EAB presence and respond to any new detections. The Oregon Department of Forestry asked that federal agencies continue to fund research and development of early detection and rapid response strategies for EAB; conservation of ash genetic resources and promotion of natural resistance; research on uses of dead ash; as well as classical biocontrol once EAB is established in a new area.

Several commenters said that they had considered APHIS to be a critically important partner in countering the EAB and were disappointed that the agency is backing away. Native Americans in particular considered the proposal to be a betrayal of the Federal government’s treaty responsibilities vis a vis recognized tribes. The Fond du Lac Band of Wisconsin wrote that upholding a federal EAB regulation is vital to the protections of important cultural and natural resources both on the Reservation and within territories ceded to the Band by several 19^th Century treaties. The tribe cited EO 13175 issued by President Clinton. The Houlton Band of Maine said APHIS has a mission to defend federally recognized tribes against invasive species. The federal government should not make a decision so contrary to its fiduciary trust responsibility to federally recognized tribes.

3) Need for continued APHIS leadership on firewood regulation

The importance of APHIS continuing to lead national efforts to curtail spread of EAB (and other pests) through careless movement of infested firewood was stressed by many commenters. Voicing this need were many of the entities which opposed the proposal, including Maine Department of Agriculture, Conservation and Forestry; Montana Department of Natural Resources and Conservation; Southern Group of State Foresters; Texas Forest Service; the two Vermont agencies; The Nature Conservancy; and the National Association of State Foresters. As noted above, the NASF, Southern Group, Texas, and Vermont all said APHIS should support creation of a national, voluntary treatment standard & label for firewood. TNC said eliminating the EAB quarantine – the best known and understood firewood regulation – will exacerbate difficulties of outreach. Public outreach and education work best when they are backed up by core consistent rules. Montana Department of Natural Resources and Conservation and NASF called for reinstating the National Firewood Task Force (which APHIS led in 2009-2010).

Several entities that supported the proposal also called for continued APHIS engagement on firewood. One, the Wisconsin DNR Division of Forestry, urged APHIS to work with the National Park Service and Forest Service to create a consistent firewood policy. A second, the NPB, noted that it is developing guidance to states interested in initiating regulations, best management practices, or outreach programs. The NBP added that it welcomes any assistance from APHIS.

As The Nature Conservancy and Tennessee Forest Health Coordinator pointed out, the firewood effort – federal regulations, state regulations, education and outreach under the “Don’t Move Firewood” campaign – all helped curb movement of several tree-killing pests, not just EAB.

4) Others Pointed Out the Importance of Consistent Regulations to Keep Markets Open

A smaller number of entities addressed the similar importance of consistent rules governing interstate and US-Canadian trade in other types of vectors that can transport EAB and which are to be deregulated under the proposal. These included the NASF. Several private groups from Maine and the Maine Department of Agriculture, Conservation and Forestry noted the importance of reaching agreement with Canada, which is a major market for their wood products. The two South Dakota departments also expressed concerns.

The National Wooden Pallet and Container Association raised the prospect of truly tremendous disruption of trade. At present, the United States and Canada exempt wood packaging originating in either country from requirements that it be treated in accordance with international standards (ISPM No. 15). Canada has many reasons to fear that crates and pallets carrying exports from the U.S. might be infested by EAB once APHIS stops enforcing quarantine regulations. If Canada responds by ending the exemption and requiring wood packaging from the U.S. to comply with ISPM#15, that action would affect a wide range of U.S. exports – from fruits to auto parts. In 2017, the U.S. exported $282 billion worth of goods to Canada (Office of the U.S. Trade Representative)

5) The Economic Analysis Underlying the Proposal was Inadequate

Several commenters criticized the adequacy of the economic analysis. The most specific criticisms were put forward by the California Forest Pest Council; CISP; the five organizations commenting under the banner of the Coalition Against Forest Pests; and the National Wooden Pallet and Container Association. The latter two cited specific Executive orders and the Paperwork Reduction Act in calling for a review of the proposal by the Office of Management and Budget & USDA Office of General Counsel to reassess whether it meets the conditions for the reduced economic analysis. As noted above, the NWPCA mentioned specifically a fear that Canada might discontinue the mutual exemption under which wood packaging may move between the two countries without being treated in accordance with ISPM#15. The possibility of such an action would certainly push the proposal over the $100 million threshold for completing much more rigorous economic analyses.

Other economic concerns not adequately addressed in the view of the commenters relate to costs arising earlier due to the faster spread of EAB to un-infested western states. Costs imposed earlier than would otherwise be the case are considered relevant in regulatory decisions. Furthermore, businesses in these and possibly other states will face new regulations adopted by states to fill the void left by federal deregulation. Finally, the lack of consistency arising from separate state regulations will impede interstate or US-Canada commerce.

Non-regulatory costs – death of trees and associated removal costs – costs to the forest industry, plus municipalities and home owners in areas not currently affected by infestation – were also not discussed in the proposal.

Several commenters said that APHIS had underestimated the ecological and cultural values threatened by spread of EAB. These included the Fond du Lac Band, Penobscot band, TNC, the Oregon soil conservation district and weed management area; Maine Mountain Collaborative and Woodland Owners, as well as several individuals.

The Nature Conservancy noted that three-quarters of the native ash range of the conterminous United States and 14 of vulnerable species in the U.S. and Mexico are still free of EAB as a result of the quarantine.

A Minnesota community’s Parks Commission noted that loss of trees to EAB can lead to other problems and costs. Consequently, the goal of “saving money” will not be achieved. In short, EAB-caused tree mortality “affects communities, including residents, homeowners, and taxpayers. Funding should be directed both to slowing the spread of the pest and to treatment of affected trees.”

A small woodland owner in Maine asked why APHIS did not evaluate economic impacts to landowners & municipalities.

Oregon’s Department of Environmental Quality Water Quality Division added that pesticides used to control EAB might cause negative impacts in riparian and aquatic environments.

6) Several Commenters questioned whether freed-up funds would support biocontrol – or whether they should

As noted in my earlier blogs, there are questions about whether biocontrol will be efficacious in protecting forests across the continent. CAFP echoed these questions. Blue Hill Heritage Trust of Maine called biocontrol experimental.

The Fond du Lac Band pointed out that most tribes don’t accept biocontrol on their reservations – so spending all available funds on this approach doesn’t help Native Americans.

The Maine government and the Penobscot Band of Maine expressed doubt that increased funding would actually materialize.

7) Comments that do not fit neatly into these categories.

The California Department of Agriculture said that it intends to promulgate a state exterior quarantine to protect its agriculture (olive trees are hosts of EAB) and environment.

The South Dakota Department of Agriculture and Department of Game, Fish and Parks concluded that interstate regulatory options should be a higher priority than other methods of control.

The Houlton Band of Maine said that maintaining the domestic quarantine is the only federal action that can adequately address the universally agreed fact that human activities cause the rapid spread of EAB.

The Western Governors Association described the region’s vulnerability to EAB spread and, citing recent Association policy resolutions, said a decision of this magnitude should be made only after substantive consultation with Western Governors.

The National Association of State Foresters pointed out that a decline in federal funding for EAB detection surveys will significantly reduce state forestry agencies’ capacity to monitor and respond to EAB spread.

The Jefferson County, Colorado Invasive Species Management team recommended retaining the quarantine using either the 100^th Meridian or Continental Divide as the containment boundary. It cited as a justifications the “culture of vigilance” created by strong quarantines. This vigilance saves financial resources and protects natural and agricultural resources.

Finally, the Fond du Lac Band of Lake Superior Chippewa said that abandoning methods that are in place for the prevention of EAB’s spread, such as federal and state quarantines, and favoring only options that focus on rehabilitating a site after it has undergone a severe infestation, presents a large and unnecessary ecological risk. Invasive species programs have always focused on “prevention” being the key.

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

Report Lists Non-Native Species in the U.S.

Ailanthus altissima

Several scientists at the United States Geological Service (USGS) have published a report and accompanying datasets that attempts to provide a publicly accessible and comprehensive list of non-native species established in United States.

Led by Annie Simpson and Meghan C. Eyler, a team of six scientists worked six years (2013–2018). They reviewed 1,166 authoritative sources to develop a list of 11,344 unique names – most of them binomials (genus and species), a few genera, plus some viruses.

This was a Herculean effort that produced very valuable products. We are all in their dept!

Simpson and Eyler point out that knowing which species are non-native to a region is a first step to managing invasive species. Lists compiled in the past were developed to serve a variety of purposes, including watch lists for preventing invasions, inventory and monitoring lists for research and modeling, regulatory lists for species control, and non-regulatory lists for raising awareness. As a result, they are not comprehensive.

Among the sources these authors consulted in preparing the list were peer-reviewed journal articles, books, brochures, circulars, databases, environmental assessments, technical reports, graduate theses, and websites.

Data – by Region

The report also notes which non-native species were established in each of three regions: the “lower 48” states, Alaska, and Hawai`i. Not surprisingly, more than half the non-native taxa are established in the vast area (nearly 7.9 million km²) comprising the “lower 48” states – 6,675 taxa. Almost half of the total number of non-native taxa have established in the tiny geographic region (only 28,311 km²) of Hawai`i – 5,848 taxa. One-tenth as many non-native taxa – 598 – are reported as established in Alaska (1.7 million km²).

This report includes taxa that are not native to any part of the specific region, but established (naturalized) somewhere in the region. An “established” species must have at least one population that is successfully reproducing or breeding in natural systems. The list includes domesticated animals and plants introduced for crops or horticulture when the taxon has escaped cultivation or captivity and become established in the wild. Species listed range from feral hogs (Sus scrofa) to plum pox virus and citrus canker to ohia rust (Puccinia psidii).

Of the total 11,344 taxa, 157 are established in all three regions. These included 125 vascular plants (especially grasses and asters); 13 arthropods, 11 mammals; 6 birds; 3 mollusks; 1 bryozoan. One of the ubiquitous plant species is tree of heaven (Ailanthus altissima). I find it entirely appropriate that the cover photo shows this tree – the photo was taken 8 miles from my home in Fairfax County, Virginia.

Nearly three-quarters (71.4%) of the non-native species in Alaska are plant species. More than half (59.7%) of the non-native species in the “lower 48” region are also plants. Nearly all the remainder of the non-native species in both regions are some kind of animal. Fungi constitute only 1.8% of the non-native species in the “lower 48” region; all the rest of the groups (Bacteria, Chromista, Protozoa, Virus) constitute less than 1% of the non-native species recorded in either region.

By contrast, in Hawai`i, animals make up 69.7% of the listed non-native species; most are invertebrates. Plants constitute 29.8% of the Hawaiian list.

Gaps, by Taxon

The authors recognize that invertebrates and microbes are under-represented because species are still being discovered; non-charismatic and difficult-to-identify species tend to be overlooked; and the species composition of any nation in this era of globalization is constantly subject to change.

I have noted some gaps among the pathogens: the absence of some of the Phytophthora that have been detected infecting shrubs and herbaceous plants in California, e.g., Phytophthora cambivora, siskiyouensis, tentaculata; and the “rapid ohia death” pathogens, Ceratocystis huliohia and C. lukuohia. Dr. Simpson is aware of these gaps and is soliciting sources to help add these organisms – especially the various Phytophthora species – to the next version of the list.

Simpson and Eyler note that the relative geographic distribution of the list at its current state seems to reinforce three well established premises: that tropical island systems are particularly vulnerable; that higher latitudes host fewer but are not invulnerable; and that species diversity in general decreases with increasing latitude.

Comparisons to Other Databases

After standardizing the names in the list by comparing them to the Integrated Taxonomic Information System (ITIS), Simpson and Eyler also reviewed the USGS BISON database, which has more than 381 million occurrence records for native and non-native species in the U.S. and Canada, covering 427,123 different taxa. (The BISON database contains significantly more species occurrences for the U.S. than the largest invasive species database, EDDMapS, which contained 4.4 million species occurrences as of June 2018.) Simpson and Eyler had to evaluate which of these taxa met their definition of non-native, since most species occurrence records in the USGS BISON are not labeled as non-native in the original records.

Comparing the BISON and non-native lists, Simpson and Eyler found that the BISON list contained a larger number of occurrence records for non-native taxa: a total of 13,450,515.However, the BISON list does not provide complete coverage of non-native species: it includes records for 77% of list of non-native species Simpson and Eyler found in Alaska, 75% of the “lower 48” sublist, but only 37% of the Hawaiian sublist.

Simpson and Eyler state their intention to continue updating the list of non-native species, they welcome contributions to it from area experts, and they urge integration of new occurrence data into invasive species database such as EDDMapS.

Indicators of Non-Native Species Richness

Figure 3 in the report (above) maps the number of non-native taxa in BISON at the county level. Figure 4 displays the proportion of non-native to native species in BISON. Higher percentages are generally evident in coastal areas and other regional hotspots. For example, the proportion in Hawaiian counties is greater than 33%. Additional data are needed to perform a more in-depth analysis of non-native species richness and abundance.

UPDATE! New Report in the Works

In June 2021, USGS announced that it was updating its Comprehensive List of Non-Native Species Established in 3 Major Regions of the U.S. so that the document more closely aligns with the parameters of the Global Register of Introduced and Invasive Species. The new USGS dataset is to be called the US Register of Introduced and Invasive Species. The list in the current draft includes 15,364 records. About 500 of these records are in Alaska, 6,000 in Hawai`i, and 8,700 in the conterminous 48 States.

One of the lead authors, Annie Simpson, contacted invasive species experts seeking feedback and suggested additions – based on authoritative resources such as peer reviewed journal articles, pest alerts, databases, books, and technical bulletins. She sought input by 25 July, 2021.

The published version of this dataset will be made freely available on USGS’ ScienceBase (https://www.sciencebase.gov), and all reviewers will be acknowledged in the dataset’s abstract.

SOURCE

Simpson, A., and Eyler, M.C., 2018, First comprehensive list of non-native species established in three major regions of the United States: U.S. Geological Survey Open-File Report 2018-1156, 15 p.

The report and accompanying data tables are available here.

South African report

In an unrelated but similar development, South Africa has issued a report on its invasive species — 2017 The Status of Biological Invasions and Their Management in South Africa. The report analyzes pathways of introduction and spread; number, distribution and impact of individual species; species richness and abundance of alien species in defined areas; and the effectiveness of interventions. The report notes that 775 invasive species have been identified to date, of which 556 are listed under some national regulatory program. Terrestrial and freshwater plants number 574 species; terrestrial invertebrates number 107 species. (This total does not include the polyphagous shot hole borer, which was detected too recently.) 107 species are considered by experts to be having either major or severe impacts on biodiversity and/or human wellbeing. Alien species richness is highest in the savanna, grassland, Indian Ocean coastal belt and fynbos biomes, lower in the more arid Karoo and desert biomes. South Africans are particularly focused on the reductions in surface water resulting from plant invasions. The decades-old “Working for Water” program has two goals: providing employment and development opportunities to disadvantaged individuals in rural areas, and managing invasive alien plants.

The Status of Biological Invasions and Their Management in South Africa is available here.

Posted by Faith Campbell

Worldwide – and U.S. – Proliferation of Phytophthora via the Nursery Trade – an Update

Phytophthora cinnanomi killing Ione manzanita in California; photo from Swiecki and Garbelotto, Distribution of Phytophthora cinnamomi within the range of Ione manzanita (Arctostaphylos myrtifolia). Agreement between the California Department of Fish and Game and University of California

Phytophthora species are plant pathogens in the oomycote group (water molds, closely related to brown algae). More than 160 species have been described; new species are continually being isolated. Many Phytophthora species are deadly to naïve hosts; examples in the United States include sudden oak death, Port-Orford cedar root disease, disease on chestnuts and oaks.

Forests in Europe – especially the United Kingdom – and Australia are also suffering high levels of mortality associated with one or more Phytophthora species.

In recent years, several studies have documented the role of nurseries in spreading non-native Phytophthora species. Two strains of P. ramorum are widespread in European nurseries and in tree plantations and wild heathlands of southwest England, Wales, parts of Scotland, and Ireland. (See here and here.)

In April 2016 I blogged about the situation in Europe described by Jung et al. 2015 (see references at the end of the blog). Jung et al. concluded that diseases caused by Phytophthora pose a substantial threat to both planted landscapes and forest ecosystems across Europe. They found 56 Phytophthora taxa in 66% of 2,525 forest and landscape planting sites that were probably introduced to those sites via nursery plantings.

Barber et al. 2013 reported nine species of Phytophthora associated with a wide variety of host species in urban streetscapes, parks, gardens, and remnant native vegetation in urban settings in Western Australia. Phytophthora spp were recovered from 30% of sampled sites.

A new summary confirms that the threat is similar in North America. In British Columbia, Dale et al. (2017) found more than two times as many Phytophthora species were detected in soil and water samples in urban areas (23) than in natural areas (11). Urban samples also showed a much higher diversity of Phytophthora per site than natural environments. These Phytophthora species had been introduced initially into urban areas and had subsequently spread into native vegetation, particularly in areas near developed sites (wildland-urban interface areas).

Swiecki et al 2018 cite several sources and their own studies to show that the large and increasingly diverse contingent of introduced Phytophthora species pose an increasingly important threat to both urban forests and surrounding native forests and plant communities in California. It is clear that shrubs and herbaceous plants as well as trees are also at risk. These scientists have repeatedly found multiple non-native Phytophthora species at individual sites in northern and southern California sites where nursery stock had been planted. Sampling in 2014 identified about 60 different Phytophthora taxa in restoration planting sites and native plant nurseries. The sampled restoration plantings were mostly located in urban riparian corridors and peri-urban parks, open spaces, or protected watersheds.

I first discussed this issue in a blog in July 2016.

Swiecki et al (2018) have also found that Phytophthora species persist in drier ecosystems. When conditions are too dry for sporangium production, Phytophthora hyphae produce resistant survival structures that can tolerate drying and persist in dead root fragments or soil. In the presence of appropriate stimuli, e.g., moisture and root exudates, resistant structures germinate to produce sporangia or hyphae, leading to new infections. Even relatively short wet periods associated with rain or irrigation can be sufficient to stimulate zoospore release. Swiecki et al (2018) list examples of numerous Phytophthora infestations that developed in dry sites, such as dry foothills of the Sierra Nevada in Amador County, and the Oakland Hills of Alameda & Contra Costa County. Swiecki et al. (2018) also note that P. cinnamomi has persisted in Australian forests in the absence of known primary hosts.

Phytophthora infections can also persist for decades in soil. In California, Swiecki et al. (2018) mention several examples:

Residual cinnamomi inoculum killed young sprouts of susceptible manzanitas (Arctostaphylos myrtifolia and A. viscida) planted on sites that were infected many years earlier.
A street planting of cork oaks (Quercus suber) apparently died due to Phytophthora root rot that had occurred 21 years earlier.
Both cinnamomi and P. cactorum were recovered from roots and soil beneath affected trees at least 60 years after the site had been a municipal woody plant nursery and adjacent residence.
A 7-acre area of native vegetation showing decline & mortality of multiple plant species was infested with multiple Phytophthora spp, including cactorum, P. cambivora, P. crassamura, P. ‘kelmania’ & P. syringae. The site was apparently infected 22 years earlier during a planting of a habitat restoration project using Ceanothus nursery stock. Subsequent spread was primarily downhill from the planting sites, facilitated by water flow, with additional spread along and near trails.

The Risk from the Nursery Trade

While Phytophthora-infested soil and plant debris can be transported on tools, vehicles, and shoes, or moved in large quantities when infested soil is excavated, graded, or imported, the principal threat is the nursery trade.

Jung et al. (2015) state that widespread contamination of nursery stock was the primary means by which these pathogens were introduced and spread in Europe. They found 49 Phytophthora taxa in 670 European nurseries. Phytophthora species were recovered from more than 90% of the sampled nurseries.
Swiecki et al. (2018) say that most of the common Phytophthora species detected in California are distributed globally, moved about with live plants or other infested materials. None is native to California.
Swiecki et al. (2018) cite studies reporting that thirteen species of Phytophthora were found in a survey for leaf spots in California nurseries in 2005 and 2006. Sampling of plants in or originating from Calif native plant nurseries alone has yielded about 60 Phytophthora At least eight species of Phytophthora were found in shipments of symptomatic and asymptomatic plants sent from west coast nurseries to Maryland. Parke et al. (2014) identified 28 Phytophthora taxa in four Oregon nurseries.
Not all infections are on the West Coast. Swiecki et al. (2081) reports that a survey in Minnesota nurseries of plants with symptoms – primarily on aboveground plant parts – found eleven species of Phytophthora.

Are scientists in other parts of the country looking for Phytophthora? I see no reason to think the situation in California is unique.

The damage caused by Phytophthora infections can be significant. In California and Oregon, sudden oak death, and Port-Orford cedar root disease, have killed well over a million trees and disrupted the ecosystems of which they are a part. There are multiple locations in Northern California where introduced Phytophthora species, especially P. cinnamomi and P. cambivora, have caused localized to extensive decline and mortality in native forests and shrublands.

Phytophthora dieback has infected more than one million hectares in Western Australia. More than 40% of the native plant species of the region are vulnerable to the causal agent, P. cinnamomi.

Phytophthora dieback in Western Australia

Dieback in native forest in Western Australia; photo copyright Western Australian Department of Parks and Wildlife

In the United Kingdom, several Phytophthora species are causing widespread mortality of native shrubs and trees and commercial plantings.

In nearly all the studies, scientists have detected previously unknown pathogen-host relationships.

The threat from spreading pathogens with wide host ranges is not limited to the genus Phytophthora. The fungus Fusarium euwallacea associated with the Kuroshio and polyphagous shot hole borers is known to kill at least 18 species of native plants in California and additional species in South Africa. The laurel wilt fungus kills many trees and shrubs in the Lauraceae family. ‘Ohi‘a or myrtle rust kills several shrubs native to Hawai`i and threatens a wide range of plants in the Myrtaceae family in Australia and New Zealand. Some insects also have wide host ranges, including the Kuroshio and polyphagous shot hole borers; and Asian longhorned and citrus longhorned beetles.

When are national and international phytosanitary agencies going to adopt policies and programs that are effective in preventing the continued spread of these highly damaging tree-killing pests? At the national level, APHIS needs to aggressively use two authorities to curtail importation of plant taxa from countries of origin which present a risk of transporting additional species of pathogens:

NAPPRA, which allows APHIS to prohibit risky imports until it has conducted a pest risk analysis.
Programs under the revised “Q-37” regulations allowing APHIS to work with exporting countries’ phytosanitary officials to implement integrated pest management strategies to ensure that plants are pathogen-free before they are exported.

I have blogged about both programs before – NAPPRA here; the Q-37 regulation strengthening here.

At the international level, the members of the International Plant Protection Convention (IPPC) must recognize the failure of the international phytosanitary system and explore ways to strengthen it. See my numerous blogs on this topic (beyond those linked to here!) by visiting www.cisp.us or www.nivemnic.us and searching under the category “forest pathogens”.

Posted by Faith Campbell

SOURCES

Jung, T. et al. 2015 “Widespread Phytophthora infestations in European nurseries put forest, semi-natural and horticultural ecosystems at high risk of Phytophthora disease” Forest Pathology. November 2015; available from Resource Gate

Swiecki, T.J., E.A. Bernhardt, and S.J. Frankel. 2018. Phytophthora root disease and the need for clean nursery stock in urban forests: Part 1 Phytophthora invasions in the urban forest & beyond. Western Arborist Fall 2018

Apparently can’t access current (2018) issues of “Western Arborist” on web unless subscribe

CISP Decision: EAB Deregulation Is Not Useful – Too Much Is at Risk

EAB; Dave Cappaert

I blogged about APHIS’ proposal to stop regulating movement of objects that can transport the emerald ash borer on 28 September. At that time, I and the Center for Invasive Species Prevention were undecided. Now we have taken a firm position: We are sympathetic to the situation in which APHIS finds itself and are disappointed that APHIS’ efforts against EAB have not been as successful as hoped. However, we believe the quarantine continues to serve a useful purpose in protecting North America’s ash (and through the firewood regulatory effort, other resources) and that the analysis APHIS provides does not justify the proposed termination of the regulatory program. Making this regulatory change, based on absent and questionable scientific data, would set a terrible precedent.

Problems Arising from Poorly Substantiated Proposal

Here I provide some additional information on points I made in the blog in September.

1) The APHIS documents are completely unbalanced. They provide no analysis of the economic or environmental impact of the regulatory changes that will allow the pest to spread more rapidly to the large areas of the country that are not yet infested.

The proposal concedes that emerald ash borer currently is known to occupy only about one quarter of the range of native Fraxinus species within the conterminous United States. As the Regulatory Flexibility Analysis states, numerous sawmills, firewood dealers, nurseries, logging/lumber companies, pallet manufacturing companies, and other establishments operate in these un-infested areas. The analysis makes no mention of the costs to millions of homeowners and property owners, thousands of municipal governments, etc., of removing and replacing ash trees on their properties that are killed by the ash borer as it spreads into new areas. The “analysis” makes no attempt to quantify impacts on any of these entities.

Examples of ash populations currently free of EAB include:

In North Dakota, 84% of the forest land area is dominated by hardwood forest types; one of the three major forest-type groups is elm/ash/cottonwood. Ash represent 38% of urban forest trees (Nowak, Hoehn, Crane, Bodine.)
In California, velvet ash (Fraxinus velutina) comprises 3.1% of the state’s street tree population (McPherson et al.). Because ash are large relative to other street trees, they provide about double the proportion of leaf cover (and associated environmental services) than the number of trees (Nowak, Hoehn, Crane, Weller, and Davila).
Portland, Oregon: ash represented 4% of urban trees (Portland Parks).

No mention is made of the additional range of Fraxinus species in Canada and Mexico that will be put at greater risk of invasion as the beetle spreads in the United States.

2) The proposal to rely on biocontrol to control EAB in the future lacks any scientific analysis of either the current biocontrol program’s effects or other possible program components.

APHIS is apparently relying on the conclusion by Duan et al. 2018 – based on models rather than field research findings – that larval and egg parasitism at about 60% would lead to a net population growth rate of EAB at a rate below replacement, therefore rapidly reducing EAB populations when such parasitism rates are accompanied by moderate to high levels of host plant resistance. If heavy woodpecker predation can be relied upon, a parasitism rate on EAB larvae of about 35% would be sufficient to achieve a similar reduction in the EAB population growth, even with limited levels of host resistance or tolerance.

However, scientific publications reviewing the impacts of the decade-old EAB biocontrol program present a mixed picture.

Our reading of several published studies indicate that two biocontrol agents (Oobius agrili and Tetrastichus planipennisi) appear to have established and spread in the northern reaches of the EAB’s U.S. range and southern Canada. At least some ash species appear to be regenerating well in some of those areas. However, it is too early to determine whether a third biocontrol agent (Spathius galinae) can protect the all-important remaining large trees, which have thicker bark. It is also too early to determine whether a different biocontrol agent (Spathius agrili) will have an impact on ash survival and regeneration in the middle latitudes (south of the 40^th parallel).

APHIS does not discuss current or planned future efforts to seek and test biocontrol agents more likely to thrive in the South and West – to which EAB will spread. It is hoped – but not yet proved – that S. agrili will be more effective south of the 40^th parallel. The article said nothing about possible agents that might be effective farther south or especially in the West.

Some scientists question the probable efficacy of biocontrol. For example, Showalter et al. note that “Despite the presence of a full complement of coevolved natural enemies in Asia, EAB has caused high mortality of North American ash species planted there … Biological control is best applied to systems in which the hosts can at least partially resist or tolerate non-native PIP [phytophagous insects and phytopathogens] attack, especially if negative density-dependent responses of natural enemies are slow relative to how long it takes the non-native PIP to kill trees.” Even Duan et al. 2018 agree that Asian ash species are more resistant (although they emphasize the large impact of natural enemies in Asia).

The scientific literature indicates that the impacts of egg parasitoid O. agrili remain uncertain (Abell et al.).

Duan et al. 2018 list and provide brief evaluations of nine possible biocontrol agents:

2: status not revealed (Sclerodermus pupariae, Atanycolus nigriventris)
2: disappointing efficacy to date (Spathius agrili, Oobius agrili)
1: apparently efficacious in some geographies in smaller trees only (Tetrastichus planipennisi)
1: promising in northern parts of EAB range but too early to evaluate (Spathius galinae)
2: considered to have too broad a host range to be released (Tenerus, Xenoglena quadrisignata)
1: release delayed pending further study (Oobius primorskyensis)

Even the impact of the most promising agent, Tetrastichus planipennisi, is not altogether clear. Duan et al. 2018 cite their life table analyses as indicating that T. planipennisi has contributed significantly to reducing net EAB population growth rates. They note a 90% reduction in EAB larval density. However, they say that this decline might be attributed in part to either the impact of the parasitoid or the general collapse of EAB populations following widespread mortality of overstory ash. (emphasis added)

3) Neither the proposal nor the supplementary materials provides any information about the current allocation of available funding among APHIS’ program components or how those allocations will change if the proposal is adopted.

For example, APHIS has set a goal of releasing biocontrol agents in every county with a known EAB infestation where the agent populations can be sustained. The proposal states that, by the end of the 2017 field season, parasitoids had been released in 27 of 32 states and 2 of 3 provinces in which EAB is present (Duan et al. 2018). APHIS does not explain how the current funding allocation hampers achieving the stated goal.

4) The proposal and accompanying regulatory flexibility analysis provide no information about whether APHIS will expand efforts supporting such other EAB impact minimization strategies as breeding trees resistant to emerald ash borer attack.

Even biocontrol practitioners (e.g., Duan et al. 2018 ) point to the importance of including breeding of resistant trees in the future efforts.

5) The proposal offers only vague promises about continuing federal efforts to minimize the risk that human transport of firewood will facilitate spread of the emerald ash borer or other tree pests.

Unfortunately, the impact of an outreach message depends heavily on having a simple, straightforward, unified message. Absent the EAB quarantine, which provides a nation-wide standard for firewood treatment, the “Don’t Move Firewood” campaign will be confronted by the task of trying to explain diverse messages and policies/rules issued by various states, counties, provinces, and managers of parks and other public lands. Hampered by this welter of messages, even the well-managed DMF campaign will struggle to persuade the public to help curtail spread via this pathway.

APHIS today published a set of “frequently asked questions” that address some of the issues raised in this blog. Go here to read the answers.

The Center for Invasive Species Prevention urges all who care about protecting North America’s native flora from non-native insects and diseases to submit comments on this proposed rule before the deadline on 19 November. This can be done by visiting here http://www.regulations.gov/#!docketDetail;D=APHIS-2017-0056.

Posted by Faith Campbell

SOURCES

Abell, K.J., L.S. Bauer, J.J. Duan, R. Van Driesche. 2014. Long-term monitoring of the introduced emerald ash borer (Coleoptera: Buprestidae) egg parasitoid, Oobius agrili (Hymenoptera: Encyrtidae), in MI, USA and evaluation of a newly developed monitoring Technique. Biological Control 79 (2014) 36–42

Duan, J.J., L.S. Bauer, R.G. van Driesche, and J.R. Gould. 2018. Progress & Challenges of Protecting North American Ash Trees from the emerald ash borer Using Biological Control. Forests 2018, 9, 142; doi:10.3390/f9030142

McPherson, G., N. van Doorn, J. de Goedec. 2016. Structure, function and value of street trees in California, USA. USDA Forest Service, Pacific Southwest Research Station Urban Forestry and Urban Greening 17 2016 (104-115)

Nowak, D.J., R.E. Hoehn III, D.E. Crane, A.R. Bodine. Assessing Urban Forest Effects and Values of the Great Plains: Kansas, Nebraska, North Dakota, South Dakota. USDA Forest Service Northern Research Station Resource Bulletin NRS-71

Nowak, D.J., R.E. Hoehn III, D.E. Crane, L. Weller, A. Davila. Assessing Urban Forest Effects and Values: Los Angeles’ Urban Forest. USDA Forest Service Northern Research Station Resource Bulletin NRS-47

Portland Parks and Recreation Street Tree Inventory Findings 2015. www.portlandoregon.gov/parks/treeinventory

Showalter, D.N., K.F. Raffa, R.A. Sniezko, D.A. Herms, A.M. Liebhold, J.A. Smith, P. Bonello. 2018. Strategic Development of Tree Resistance Against Forest Pathogen and Insect Invasions in Defense-Free Space. Frontiers in Ecology & Evolution