Category: forest pests

Updates on 1) hemlocks 2) shot hole borers/Fusarium & 3) beech leaf disease

symptoms of beech leaf disease; photo by Dr. Chagas de Freitas

Three webinars during April and May provided updates on efforts to address three non-native, tree-killing pests: hemlock woolly adelgid (HWA), link invasive shot hole borers (ISHB), link and beech leaf disease (BLD) link. I attended each and summarize here.  

  1. Hemlock conservation in North Carolina  – the NC Hemlock Restoration Initiative (HRI) see SaveHemlocksNC.org  

The webinar was recorded at Hope for the Hemlocks: HWA Management Approaches on Public and Private Lands in North Carolina.  You probably need to be a member of the Natural Areas Association to watch the archived version.

I was pleased to learn about the major effort under way in North Carolina, where eastern and Carolina hemlocks are extremely important components of multiple ecosystems. In 2013, the Commissioner of Agriculture decided to make protecting hemlocks a signature project. He wanted to ensure that three state agencies – the Forest Service, Wildlife Department, and State Parks – worked together to improve the efficacy of treating trees. (Treatments available at the time were expensive and time-consuming.)

HRI treatment at Conestee Falls; HRI photo

Thom Green described the result: North Carolina’s Hemlock Restoration Initiative (HRI). The initiative is administered by the Western North Carolina Communities – a non-governmental organization with strong connections to rural communities and a history of successful collaborative projects that support agriculture and forestry. It engages state agencies, local and county governments, local NGOs, and federal agencies and works on both public and private lands with the goal of ensuring that hemlocks can survive to maturity.

HRI staff work with local partners to identify priority hemlock conservation areas (HCAs). It then sends a “strike team” to guide the partners in treating as many trees as possible. (North Carolina allows non-licensed volunteers to apply pesticides under supervision; also, landowners can treat trees on their own property.) These collaborative projects can treat up to 1,000 trees per day.

The chemicals used are imidacloprid and, where poor tree health justifies emergency treatment, dinotefuran. These are usually applied as a soil drench because it is easier for people to transport the equipment into the woods. Bark spray is used in sensitive areas. They have found that imidacloprid provides five to seven years of protection. A new product, CoreTech, is even easier to transport and works much faster than imidacloprid, however, it costs more.

The HRI believes it is minimizing non-target impacts of the neonictenoid imidacloprid because:

  • hemlocks are pollinated by wind, not insects
    • hemlocks don’t exude resins that attract insects
    • pesticide applications are tightly targetted at the base of trunk, with 10-foot setbacks from water
    • long intervals between treatments (5 – 7 years) allow soil invertebrates to recover

The program has treated 100,000 trees between 2016 and 2021 on state and private lands. Now they are starting the second round of treatments for trees treated at the beginning of the program.

Treatment priorities are based primarily on the extent to which the trees are able to take up the chemical, evaluated by the percentage of the crown that is alive and the density of foliage. Since imidacloprid can take a year to reach the canopy of a mature tree, it is used only on trees with greater than half the crown rated as healthy. When trees have a lower status, dinotefuran is added (because it can reach the canopy within weeks).  Trees with less than 30% live crown are not treated.

The Initiative also supports biocontrol programs. It has assisted releases of Laricobius nigrinis (a beetle in the family Derodontidae) and helps volunteers monitor releases and survival. Dr. Green reports that L. nigrinis has spread almost throughout western North Carolina but that questions remain regarding its impact on tree health. He thinks biocontrol is not yet reliable as stand-alone tool; success will require a suite of predatory insects.

Forest Restoration Alliance potting hemlock seedlings; HRI photo

The HRI measures the success of various treatments (Hurray!). “Impact plots” are established at the start of treatment. Staff or volunteers return every three years to monitor all aspects of the health of a few designated trees – including untreated ones. So far, they have seen encouraging responses in crown density and new growth.

  • Invasive Shot Hole Borers (ISHB) in California

See www.ishb.org and video recordings of the meeting at:  

https://youtu.be/RyqJYyLkshk (Day 1); and https://youtu.be/kWmtcbjTczw (Day 2)

A host of scientists from California spent two full days describing research and management projects funded by specific state legislation – Assembly Bill (AB)-2470 on two invasive shot hole borers.

Adoption of this legislation resulted largely from lobbying by John Kabashima. Additional funding was provided by CalFire (the state’s forestry agency). The agency responsible for managing invasive species – California Department of Food and Agriculture (CDFA) had designated these organisms as not a threat to agriculture. So it did not fund many necessary activities.

The Problem and Where It Is

“Fusarium dieback” is the disease caused by this insect-pathogen complex. The insects involved are two ambrosia beetles in the Euwallacea genus – the polyphagous (E. whitfordiodendrus) and Kuroshio (E. Kuroshio) shot hole borers. link to DMFAccording to Dr. Bea Nabua-Behermann, Urban Forestry and Natural Resources Advisor with University of California Cooperative Extension (UCCE), other fungi are present on both beetle species but its matching Fusarium sp. is the principal associated fungus and is required for the beetle’s reproduction. These are Fusarium euwallaceae and F. kuroshium.

As of spring 2022, the beetle/fungus complex has spread as far north as Santa Barbara /Santa Clarita; and inland to San Bernardino and Riverside (see the map here). They are very widespread in Orange and San Diego counties. At least 65 tree species in southern California are reproductive hosts (globally, it is 77 species; see full list here). The preferred and most succeptible hosts are several species in the Acer, Parkinsonia, Platanus, Quercus, and Salix genera. Box elder (A. negundo) is so susceptible that it is considered a sentinel tree.

Because the beetles spend most of their life inside trees, their life cycle leaves few opportunities to combat them. Females (only) fly but tend to bore galleries on their natal tree. Several speakers on the webinar said management should focus on heavily infested “amplifier trees”. Much spread is human assisted since the beetles can survive in dead wood for months if it is damp enough for the fungus.  Possible vectors are green waste, firewood, and even large wood chips or mulch.

Management – from Trapping to Rapid Response to Restoration

Akiv Eskalen of University of California Davis discussed trapping and monitoring techniques to confirm presence of the insect and pathogen. Also, he talked about setting priorities for treating trees based on the presence of reproductive hosts, host value, infestation level, and whether the trees pose a safety hazard. The disease causes too little damage to some hosts to warrant management. He emphasized the importance of preventing spread. This requires close monitoring of infested trees to see whether beetles move to neighbors. Dr. Eskalen described a major and intensive monitoring and treatment program at Disneyland. The 600 acres of parks, hotels, and parking lots have ~16,000 trees belonging to 681 species.

Several speakers described on-going efforts in Orange County. Danny Hirchag (IPM manager for Orange County Parks) described how his agency is managing 60,000 acres of variable woodlands containing 42,000 trees, of which 55% are hosts of ISHB and their associated fungi. Of greatest concern are California sycamore and coast live oak in areas of heavy public use. The highest priority is protecting public safety; next is protecting historic trees (which can’t be replaced); third is minimizing impacts to ecosystem services. Orange County Parks is currently removing fewer than 50 trees each year. Hirchag noted the importance of collaborating in the research trials conducted by the University of California Cooperative Extension.

infested California sycamore; photo by Bea Nabua-Behermann

Maximiliano Regis and Rachel Burnap, of County of Los Angeles Department of Agricultural Commissioner/Weights and Measures, described Los Angeles County’s efforts more broadly. The challenge is clear: LA County has more than 160 parks. In 2021, they placed nearly 2,500 traps, mapped infected trees, carried out on-ground surveys to find amplifier trees, removed both amplifier and hazard trees (using funds provided by CalFire), and educated the public. Their efforts were guided by an early detection-rapid response (ED/RR) Plan (2019) developed by Rosi Dagit (see below). While London plane trees (Platanus x hispanica) and California sycamores (Platanus racemose) were initially most affected, now black locusts (Robinia pseudoacacia) and box elders (Acer negundo) are succumbing. [Note: both are widespread across North America.] The researchers are trying to determine why some areas are largely untouched, despite the presence of the same tree species. Regis and Burnap noted the increasing difficulty getting confirmation of the pathogen’s presence because laboratories are overwhelmed. They continue looking for funding sources.

Rosi Dagit, Senior Conservation Biologist, Resource Conservation District of the Santa Monica Mountains, described the creation of that ED/RR system for Los Angeles County as a whole, without regard for property lines. Participants established random study plots across the entire Santa Monica Mountains Natural Recreation Area (NRA), based on proximity to areas of particularly sensitive ecological concerns. The fact that the NRA’s forests are aging and that the risk of infestations is especially high in riparian forests helped persuade policy-makers to fund the effort. The accompanying rapid response plan informs everyone about what to do, who should do it, and who pays. This information incorporates agencies’ rules about what and where to plant. It also provides measures to evaluate whether the action was effective. It did take more than two years for the county to set staffing needs etc.

John Kabashima link discussed his criteria for replanting and ecosystem restoration following tree removal in the southern California region. He recommends prompt removal of amplifier trees – especially box elder and California sycamore. He relies on replanting guidance developed by UC-Irvine (which is on the website) – especially avoiding monocultures. Kabashima reiterated the importance of close monitoring to track beetle populations and responding quickly if they build up.

Economics of Urban Forests and Cities Most at Risk

Karen Jetter (an economist at the UC Agriculture Issues Center) has developed a model to compare the costs of an early detection program to the environmental and monetary costs of infestation by Fusarium disease.  She noted that early detection and monitoring programs are often hard to justify because — when they are successful — nothing changes! She found that averted or delayed costs (including tree removals, lost ecosystem services, lost landscape asset value [replanting value] and the cost to replant) always far exceeded the cost of monitoring programs. Unfortunately, a written report about this effort (Jetter, K., A. Hollander, B.E. Nobua-Behrmann, N. Love, S. Lynch, E. Teach, N. Van Dorne, J. Kabashima, and J. Thorne. 2022. Bioeconomic Modeling of Invasive Species Management in Urban Forests; Final Report)   appears to be available only through the University of California “collaborative tools” website dedicated to practitioners and stakeholders engaged on ISHB issues. If you are not a member of the list, contact me using the comment button and ask that I send it to you. Include your email address (the comment process makes determining emails difficult if not impossible.)

Shannon Lynch (UC Davis) developed a model to estimate vulnerability of urban areas based on phylogenetic structure (relationship between tree species), host abundance, and number of beetle generations/year (linked to temperature). She found that areas with less favorable host communities can become vulnerable if the climate becomes favorable. Where the host community is already favorable, climate not important.

She evaluated 170 California cities based on their tree inventories. The cities at highest risk were San Diego, Los Angeles, the San Francisco Bay area, and the Central Valley – e.g., Sacramento. For areas lacking tree inventories, she based her risk determination on the estimated number of generations of beetles per year – based on climate. This analysis posited a very high risk in the eastern half of southern California and the Central Valley. Participants all recognized the need to apply this model to cities in Arizona and Nevada.

Possible Management Strategies

Shannon Lynch (UC Davis) studied whether endophytes might be used to kill the Fusarium fungi. She reported finding 771 fungal strains and 657 bacterial strains in tree microbiomes. Some of the fungal isolates impeded growth of the Fusarium fungi in a petri dish. She began testing whether these fungi can be used to inoculate cuttings that are to be used for restoration. She also planned to test more endophytes, and more native plant species to explore creation of a multi-fungus cocktail.

Richard Stouthamer of UC Riverside is exploring possible biocontrol agents. Of three he has evaluated, the most promising is Phasmastichus sp., which is new to science. He is still trying to establish laboratory cultures so he can test its host specificity.

See bldresearch@lists.osu.edu

symptoms of beech leaf disease; photo by Dr. Chagas de Freitas

At this meeting, scientists described research aimed at improving basic understanding of beech leaf disease’s causal agents, its mechanisms of spread, etc.  Their findings are mostly preliminary.

These findings are of greatest importance now:

  • presence of the nematodes varies considerably across leaf surface – if one collects samples from the wrong site on leaf, one won’t detect nematode (Paulo Vieria, Agriculture Research Service)
    • developing predictive risk maps that combines temperature, humidity, elevation, soils (Ersan Selvi, Ohio State). So far, he has found that BLD is greater in humid areas – including under closed forest canopies. The USFS is funding studies aimed at incorporating disease severity in detection apps.
    • determining extent of nematode presence. Sharon Reed of Ontario has found nematode DNA in trap fluids throughout the Province. It is much more common at known disease sites. Reed is also studying the presence of arthropods on beech leaves and buds.

Longer term findings and questions

  • possible vectors:
    • nematode DNA has been detected from birds – although it is not clear whether the DNA came from bird  feces, feathers, or dust (DK Martin)
    • a few live nematodes have been extracted from the excrement of caterpillars that fed on infected leaves (Mihail Kantor, ARS)
    • nematode damage to leaves:
      • presence of the nematode in leaf buds before they open (Vieria and Joe Mowery, both ARS). The nematode can create considerable damage in leaf buds before they open. Nematodes are present as early as October of the preceding year.
      • damage to leaves by nematode (Mowery, ARS) Leaf epidermal cells are distorted, stomata blocked, chlorobasts are larger than normal, irregular shape
    • possible management tools
      • are there parasites that might attack the nematode? (Paulo Vieria, ARS)
      • experimental treatment of infested trees using phosphite (Kandor, ARS)
    • ecology: how do root microbiomes compare on infested and healthy trees? (Caleb Kime, Ohio State; and David Burke, Vice President for Science at Holden Arboretum)
infested European beech in Rhode Island; photo by Dr. Nathanial A. Mitkowski

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.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

or

www.fadingforests.org

Canada’s 64th Forest Pest Management Forum — in Short

spruce budworm; photo by Jerry E. Dewey, USFS; via Bugwood

The 64th Forest Pest Management Forum was held in December 2021. This is the largest and most significant gathering of forest pest management experts, managers, and practitioners in Canada. The proceedngs are available here. I summarize the contents. (This is my third review of recent reports on invasive species by Canadians. See also here and here. I appeciate the opportunity to learn about forest pest issues across such a large proportion of North America!

As usual, much of the attention was given to native pests, e.g.,

  • mountain pine beetle (Dendroctonus ponderosae) in Yukon, Alberta [declining numbers and areas affected]; Saskatchewan [none found in boreal forest]
  • Jack pine budworm (Choristoneura pinus) – Saskatchewan, Manitoba, Ontario.  [damage to jack pine in the Northwest Territories is caused by an unknown agent]
  • spruce pests, including spruce budworm (Choristoneura fumiferana) across the country: from  Yukon and Northwest Territories to New Brunswick; Nova Scotia; Newfoundland and Labrador
  • aspen defoliators – British Columbia; Northwest Territories; Alberta; Saskatchewan;
  • Swiss Needle Cast – British Columbia
  • Septoria leaf and stem blight in hybrid poplars (Populus genus) spreading in British Columbia; fears it could threaten black cottonwood, a keystone species in riparian ecosystems
hemlock mortality caused by HWA in Nova Scotia; photo by Celia Boone, NSDLF

The meeting also reported the following on non-native forest pests:

  • Asian longhorned beetle (Anoplophora glabripennis) — Canada has been declared free of ALB; national grid-based detection surveys continue – visual surveys at 10 sites; none found
  • emerald ash borer (Agrilus planipennis) — trapping focused on high-risk locations and urban centers outside established regulated areas with no new detections in 2021. Saskatchewan continues to regulate EAB as a quarantine pest – after its detection in Winnipeg in November 2017. In New Brunswick, EAB has spread throughout the region where it was originally discovered in early 2021. In Nova Scotia, EAB remains undetected outside of the regulated area of Halifax
  • spongy moth (Lymantria dispar dispar) – trapping continues across Canada; detections in all provinces except Newfoundland – Labrador. Officials think they have eradicated an incipient population in Manitoba. Outbreaks are intensifying in Ontario and Québec (spongy moth is also expanding in northern US)
  • brown spruce longhorned beetle (Tetropium fuscum) – widespread trapping in Nova Scotia detected no new finds.
  • hemlock woolly adelgid (Adelges tsugae) is a priority species. Hemlock is a major component of the forested regions in the eastern provinces and HWA threatens to cause potentially irreparable damage to hemlock-dominated areas. Visual detection surveys were conducted at more than 180 high risk locations in eastern Canada. HWA has been confirmed in 7 counties of Nova Scotia – 2 of them new; plus a new infestation in Ontario.
  • beech leaf-mining weevil (Orchestes fagi) — continues to spread, with 22,129 ha of damage and mortality in areas near Halifax, Nova Scotia. The report makes no mention of beech leaf disease and here.
  • Dutch elm disease (Ophiostoma ulmi & O.novo-ulmi) – spreading rapidly in parts of Saskatchewan; major control effort in Manitoba, where 38 communities are participating in a provincial program and Winnipeg has its own program.
  • elm zig zag sawfly (Aproceros leucopoda) – Canadian authorities are apparently considering what their response should be  [see also Martel et al. 2022. (open access!) 
elm zigzag sawfly; photo by Gyorgy Csoka Hungarian Forest Research Organization; via Bugwood

Canadian authorities have active surveillance programs targetting three species established in the U.S. which they worry will enter Canada:

spotted lanternfly eggs; New York Dept. of Environmental Conservation photo
  • oak wilt (Ceratocystis fagacearum) – visual surveys at more than 60 sites in Ontario, Québec, New Brunswick and Nova Scotia; so far, no detections.
  • spotted lanternfly (Lycorma delicatula) authorities noted the many possible pathways of introduction
  • brown-tail moth (Euproctis chrysorrhoea) – rising population in Maine; several additional public reports of sightings in New Brunswick.

Policy

Canada has a National Forest Pest Strategy adopted by the Canadian Council of Forest Ministers (CCFM) in 2007. The CCFM Forest Pest Working Group (FPWG) plays a major role in advancing this Strategy. It also provides a national forum for generating ideas and exchanging information about forest pest management among federal, provincial, and territorial government agencies.

According to officials of the Canadian Food Inspection Agency (CFIA), the government has initiated limited pathway-based surveys to detect introduced pests associated with wood packaging material (crates, pallets, etc.). [See additional blogs posted here under “wood packaging” category. E.g., this one.  The agency is also developing an efficient, safe and feasible management program for handling shipborne dunnage. CFIA expected to publish a revised directive in spring 2022, then fully implement it by fall 2022.

Presentations on Individual Pests

The Proceedings include abstracts of presentations on individual species. The abstracts rarely provide the final findings.

Emma J. Hudgins, of Carleton University, reported on ways to optimize control of EAB in the U.S. She found that the best management strategy combined site-focused activities – such as biocontrol — and spread-focused (quarantine) management measures. This combined strategy vastly outperformed efforts based on limiting propagule pressure or managing single sites. In other words, quarantines should be refined rather than abandoned – as the US has done.

Oregon ash forest on the Willamette River, Oregon; photo by W. Williams, Oregon Dept. of Forestry

Chris MacQuarrie of the Canadian Forest Service reviewed use of biocontrol agents targetting EAB. Canada has approved release of three agents also approved in the United States: Tetrastichus planipennisi in 2013; Oobius agrili in 2015; Spathius galinae in 2017. Canada began trying to evaluate their impacts in 2018 – but the results are not included in the abstract.

Lucas Roscoe, also of the Canadian Forest Service, reviewed biocontrol efforts targetting hemlock woolly adelgid. The abstract doesn’t provide conclusions.

Kevin Porter and James Brandt assessed the risk of the spruce budworm (Choristoneura fumiferana) outbreaks in Eastern Canada’s Forests. The insect is the most widely distributed and destructive pest of spruce-fir forests in Canada; it is native to much of boreal and hemiboreal North America. Outbreaks occur periodically. Cumulative tree defoliation and mortality can result in significant losses of important timber and non-timber resources, affecting the forest industry and forest-dependent communities.

Stefan Zeglen and Nicolas Feau reported on the importance of environmental conditions in causing one disease. Swiss Needle Cast (caused by the usually innocuous endophyte Nothophaeocryptopus gaeumannii) has become pathogenic on Douglas-fir, causing up to 60% growth loss. This results from changing climate – and is expected to worsen with rising temperatures and humidity.

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.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

or

www.fadingforests.org

Invasions cost protected areas more than $22 billion in 35 years

Burmese python in Everglades National Park; photo by Bob Reed, US FWS

Scientists continue to apply data collected in an international database (InvaCost; see “methods” section of Cuthbert et al.; full citation at end of this blog) to estimate the economic costs associated with invasive alien species (IAS). These sources reported $22.24 billion in economic costs of bioinvasion in protected areas over the 35-year period 1975 – 2020. Because the data has significant gaps, no doubt invasions really cost much more.

Moodley et al. 2022 (full citation at end of this blog) attempt to apply these data to analyze economic costs in protected areas. As they note, protected areas are a pillar of global biodiversity conservation. So it is important to understand the extent to which bioinvasion threatens this purpose. 

Unfortunately, the data are still too scant to support any conclusions. Such distortions are acknowledged by Moodley et al. I will discuss the data gaps below a summary of the study’s findings.

The Details

Of the estimated $22.24 billion, only 4% were observed costs; 96% were “potential” costs (= extrapolated or predicted based on models). Both had generally increased in more recent years, especially “potential” costs after 1995. As is true in other analyses of InvaCost data, the great majority (73%) of observed costs covered management efforts rather than losses due to impacts. The 24% of total costs ascribed to losses, or damage, exceeded the authors’ expectation. They had thought that the minimal presence of human infrastructure inside protected areas would result in low records of “economic” damages.

The great majority (83%) of reported management costs were reactive, that is, undertaken after the invasion had occurred. In terrestrial environments, there were significantly higher bioinvasion costs inside protected areas than outside (although this varied by continent). However, when considering predicted or modelled costs, the importance was reversed: expected management costs represented only 5% while these “potential” damages were 94%.

Higher expenditures were reported in more developed countries – which have more resources to allocate and are better able to carry out research documenting both damage and effort. 

More than 80% of management costs were shouldered by governmental services and/or official organizations (e.g. conservation agencies, forest services, or associations). The “agriculture” and “public and social welfare” sectors sustained 60% of observed “damage” and 89% of “mixed damage and management” costs respectively. The “environmental” and “public and social welfare” sectors together accounted for 94% of all the “potential” costs (predicted based on models) generated by invasive species in protected areas; 99% of damage costs. With the partial exception of the agricultural sector, the economic sectors that contribute the most to movement to invasive species are spared from carrying the resulting costs.

Lord Howe Island, Australia; threatened by myrtle rust; photo by Robert Whyte, via Flickr

Invasive plants dominated by numbers of published reports – 64% of reports of observed costs, 79% of reports of “potential”. However, both actual and “potential” costs allotted to plant invasions were much lower than for vertebrates and invertebrates. Mammals and insects dominated observed animal costs.

It is often asserted that protected areas are less vulnerable to bioinvasion because of the relative absence of human activity. Moodley et al. suggest the contrary: that protected areas might be more vulnerable to bioinvasion because they often host a larger proportion of native, endemic and threatened species less adapted to anthropogenic disturbances. Of course, no place on Earth is free of anthropogenic influences; this was true even before climate change became an overriding threat. Plenty of U.S. National parks and wilderness areas have suffered invasion by species that are causing significant change (see, for example, here, here, and here).

Despite Best Efforts, Data are Scant and Skewed

Economic data on invasive species in protected areas were available for only a tiny proportion of these sites — 55 out of 266,561 protected areas.

As Moodley et al. state, their study was hampered by several data gaps:

  1. Taxonomic bias – plants are both more frequently studied and managed in protected areas, but their reported observed costs are substantially lower than those of either mammals or insects.
  2. The data relate to economic rather than ecological effects. The costliest species economically might not cause the greatest ecological harm.
  3. Geographical bias – studies are more plentiful in the Americas and Pacific Islands. However, studies from Europe, Africa and South America more often report observed costs. The South African attention to invasive species (see blogs here, here, and here), and economic importance of tourism to the Galápagos Islands exacerbate these data biases.
  4. Methodological bias – although reporting bioinvasion costs has steadily increased, it is still erratic and dominated by “potential” costs = predictions, models or simulations.

I note that, in addition, individual examples of high-cost invasive species are not representative. The highest costs reported pertained to one agricultural pest (mango beetle) and one human health threat (mosquitoes).

Great Smokey Mountains National Park; threatened by mammals (pigs), forest pests, worms, invasive plants … Photo by Domenico Convertini via Flickr

As these weaknesses demonstrate, a significant need remains for increased attention to the economic aspects of bioinvasion – especially since political leaders pay so much greater attention to economics than to other metrics. However, the reported costs – $22.24 billion over 35 years, and growing! – are sufficient in the view of Moodley et al. to support advocating investment of more resources in invasive species management in protected areas, including – or especially – it is not quite clear — preventative measures.

SOURCES

Cuthbert, R.N., C Diagne, E.J. Hudgins, A. Turbelin, D.A. Ahmed, C. Albert, T.W. Bodey, E. Briski, F. Essl, P.J. Haubrock, R.E. Gozlan, N. Kirichenko, M. Kourantidou, A.M. Kramer, F. Courchamp. 2022. Bioinvasion cost reveals insufficient proactive management worldwide. Science of The Total Environment Volume 819, 1 May, 2022, 153404

Moodley, D., E. Angulo, R.N. Cuthbert, B. Leung, A. Turbelin, A. Novoa, M. Kourantidou, G. Heringer, P.J. Haubrock, D. Renault, M. Robuchon, J. Fantle-Lepczyk, F. Courchamp, C. Diagne. 2022.  Surprisingly high economic costs of bioinvasions in protected areas. Biol Invasions. https://doi.org/10.1007/s10530-022-02732-7

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.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

or www.fadingforests.org

Trees’ Value – High Although Major Benefits Not Addressed

loblolly pine – tree species showing highest value in this study; via Flickr

More scientists are examining the importance of American forests in providing ecosystem services – and the threat to those values raised by non-native pests and other factors. This is a broader perspective than used in the past – and it includes climate change.   also here  

Jeannine Cavender-Bareu and colleagues (full citation at the end of this blog) found that changes in the abundance and composition of US trees have the potential to undermine the benefits and societal values derived from those forests now. They examined threats associated with increasing invasive pests and pathogens, greater frequency of major fires, and climate change. Together, these constitute a complex set of global change drivers – and the impact of each is accelerating.

The authors tried to measure the impact of these forces on forests’ ability to provide five key ecosystem services. Two are “regulating” services—regulation of climate and air quality. The other three are “provisioning” services—production of wood products, food crops, and Christmas trees.

Unfortunately, they could not find sufficient data to analyze five other ecosystem services, which are equally or more important. They include both regulatory and provisioning services: water management, such as erosion control, flood and storm surge regulation; urban heat island regulation and energy savings; providing habitats for species (biodiversity); recreation; or ornamental, spiritual, and aesthetic values.

Cavender-Bareu and colleagues concluded that the value of the five analyzed services provided by 400 tree species across the contiguous United States over the years 2010-2012 is $114 billion per year. The non-market “regulatory” values far exceeds their current commercial value. 

  • Climate regulation via carbon storage in tree biomass provides 51% of this net annual value;
  • Human health improvements linked to trees’ filtering of air pollution provide an additional 37% of the annual net value.
  • Provisioning services, such as wood products, fruit and nut crops, and Christmas trees, provide only 12% of the net annual value. (By my calculation, wood products constituate almost three-quarters of this sum.)

The authors then tried to identify which tree lineages, e.g., taxonomic families, genera, or species, provide the greatest proportion of each of these ecosystem services. They also identified threats to these lineages. Together, this knowledge allows managers to target forestry management practices to the specific lineages within a landscape where ecosystem service are most at risk.

Table 1 in the article ranks 10 tree genera by the aggregate net value they provide: pine, oak, maple, Douglas-fir, hemlock, cherry/almond, spruce, hickories, yellow or tulip poplar, and ash. The table also provides separate dollar values for each of the five benefits.

Two lineages—pines and oaks — provide 42% of the value of these services (annually, pines = $25.4 billion; oaks = $22.3 billion). They note that these high values result from the large number of pine and oak species occupying diverse ecological niches. Oaks have the highest annual values for climate moderation or carbon storage ($10.7 billion) and air quality regulation ($11 billion). Oaks’ air quality regulation value reflects three factors: the genus’ abundance, the trees’ size, and the large numbers planted in cities and suburbs, that is, near human populations affected by pollution. Other than this issue of location, closely related tree species tend to have similar air quality regulation values.

Many lineages provide wood products, but the amounts vary widely among related species. Pines dominate annual net revenues from wood products at $7.4 billion, due in part to their high volume and higher than average price. The most valuable species in the context of this study’s set of ecosystem services are loblolly pine (Pinus taeda) and Douglas-fir (Pseudotsuga menziesii).

Edible fruits are concentrated in two lineages — family Rosaceae, especially genera Prunus and Malus; and family Rutaceae, genus Citrus. This category demonstrates the impact of disease: annual net returns from citrus products were actually negative during the 2010 – 2012 period due to abnormally low market prices and the prevalence of citrus greening disease in Florida, Arizona and California.

northern red oak – high value for timber & carbon sequestration; photo by dcrjsr via Wikimedia

Trees at Risk

As climate change progresses, the mix of tree species that provide critical ecosystem services will be altered—with unknown consequences. There could be increases in some services but also widely-expected losses in ecosystem benefits and human well-being.

An estimated 81% of tree species are projected to have at least 10% of their biomass exposed to climates outside their current climate envelope, impacting nearly 40% of total tree biomass in the contiguous U.S. An estimated 40% of species are projected to face increasing fire frequency. In both cases, individual species’ vulnerability depends more on where that species grows than on its genetic lineage. This analysis demonstrates a threatening interaction between these two disturbance agents: the species most valuable for carbon storage are also the most at risk from the increasing fire threat.

Known (established) pests threaten 16% of tree species and potentially affect up to 40% of total tree biomass. At greatest risk are the oak and pine genera (due to mountain pine beetle and oak wilt) plus most of the crop species. The authors cite chestnut blight and Dutch elm disease as examples of pests decimating once-dominant tree species — ones provided many services. In contrast to climate and fire risks, genetic relationships explain much of the risk of pest damage because most pests attack individual species, genera, or families.  (There are exceptions – sudden oak death and the Fusarium fungi vectored by invasive shot hole borers attack species across a wide range of families.)

Cavender-Bareu and colleagues conclude that major losses to pest attack of dominant species and lineages that currently provide high-value ecosystem services would undermine forest capacity to provide important benefits—at least for decades. They note that pest threats appear to be increasing partially as a consequence of climate change, demonstrating that multiple threats can interact and exacerbate outcomes. They say policy interventions aimed at slowing pests’ spread will probably be necessary to preserve the ecosystem service of climate and air quality regulation.

The high diversity of tree taxa in U.S. forests might buffer losses of ecosystem service if the most valuable lineages (oaks and pines) are compromised. However, other species will be needed to fill the voids their loss creates. Ensuring this possibility will require intentional management of forests and trees in the face of myriad and simultaneous threats.

The authors also show how tree-provided ecosystem services are distributed across the U.S. depending largely on the locations of forests, tree plantations, and orchards. Climate and air quality regulation occurs everywhere forests grow. Timber production is concentrated in a subset of the regions that also produce high climate regulation and air pollution removal, including the Southeast, Pacific Northwest, Northeast, and Upper Midwest.

The most valuable tree crops are grown on the coasts, often where forests do not grow—e.g., California; and in several Southwestern, Southern, and Eastern states.

Cavender-Bareu and colleagues found that climate change threatens species in all parts of the continent. Wildfires are expected to increase especially in California and the Intermountain West, which they say coincides with high annual storage of carbon. (This finding is opposite from those of Quirion et al. (2021) which pointed to the slow growth of pines in this region as reducing carbon storage potential.)

Cavender-Bareu and colleagues found that pest threats are highest in the Southwest and Southeast. These pests (native and non-native) are predicted to disproportionally affect species that generate high annual net values for climate regulation, air quality regulation, and wood products – e.g., pines and oaks. As noted above, these values are driven by their abundance. They note that mountain pine beetle and oak wilt have not yet reached areas with high wood product production in Northeast and Southeast.

Other studies (see Aukema et al. 2010) and here & here show that the greatest threats from non-native pests are to the Northeast/Midwest, and the Pacific coast – and Hawai`i & here.

Rock Creek Park, Washington, D.C. – an urban forest! photo by Bonnachaven

Cavender-Bareu and colleagues’ analysis advances our understanding of the threat several change drivers pose to benefits Americans receive from our forests. However, we must remember that some of the most important ecosystem services were not included because of insufficient data. Missing services:

1) most urban ecosystems. Inclusion of urban trees in the analysis would significantly increase the value of avoided health damage due to tree-based removal of air pollution. Urban trees also help regulate climate change (Nowak et al. estimate 643 M Mg of carbon are stored in urban areas, at a value of $2.31 billion annually).

2) many other regulating ecosystem services, such as erosion control, flood regulation, storm surge regulation, urban heat island regulation, energy savings due to shade, and species habitat / biodiversity.

3) recreation, ornamental, spiritual, and aesthetic values.

A complete accounting would also require estimates of the damage trees cause and the cost of their maintenance. For example, the full cost of irrigating almond trees; allergies and irritations due to tree pollen and sap; injuries to people and property caused by falling trees and limbs; trees’ role in spreading fires; trees’ contribution to volatile organic compounds (a pollutant).

The estimated annual values of the climate and air quality regulation have large uncertainty. These arise from uncertainty re: the social cost of carbon, the value of a statistical life, and uncertainty in the air pollution dose–mortality response function. The estimated annual values of the provisioning services are more precise because they are calculated from the market price for the per unit value of tree crops, wood products, and Christmas trees, as well as reliable data on production volume.

SOURCES

Aukema, J.E., D.G. McCullough, B. Von Holle, A.M. Liebhold, K. Britton, & S.J. Frankel. 2010. Historical Accumulation of Nonindigenous Forest Pests in the Continental United States. Bioscience. December 2010 / Vol. 60 No. 11

Cavender-Bareu, J.M., E. Nelson, J.E. Meireles, J.R. Lasky, D.A. Miteva, D.J.Nowak, W.D. Pearse, M.R. Helmus, A.E. Zanne, W.F. Fagan, C. Mihiar, N.Z. Muller, N.J.B. Kraft, S. Polasky. 2022. The hidden value of trees — Quantifying the ecosystem services of tree lineages and their major threats across the contiguous. PLOS Sustainability and Transformation April 5, 2022.  

Quirion BR, Domke GM, Walters BF, Lovett GM, Fargione JE, Greenwood L, Serbesoff-King K, Randall JM & Fei S (2021) Insect and Disease Disturbances Correlate With Reduced Carbon Sequestration in Forests of the Contiguous United States. Front. For. Glob. Change 4:716582.  Volume 4 Article 716582  doi: 10.3389/ffgc.2021.716582

Comment to APHIS on its Strategic Plan

APHIS is seeking stakeholder input to its new strategic plan to guide the agency’s work over the next 5 years.

The strategic plan framework is a summary of the draft plan; it provides highlights including the mission and vision statements, core values, strategic goals and objectives, and trends or signals of change we expect to influence the agency’s work in the future. APHIS is seeking input on the following questions:

  • Are your interests represented in the plan?
  • Are there opportunities for APHIS to partner with others to achieve the goals and objectives?
  • Are there other trends for which the agency should be preparing?
  • Are there additional items APHIS should consider for the plan?

range of American beech – should APHIS be doing more to protect it from 3 non-native pests?

The strategic plan framework is available at https://www.regulations.gov/document/APHIS-2022-0035-0001

To comment, please visit: https://www.regulations.gov/docket/APHIS-2022-0035

Comments must be received by July 1, 2022, 11:59pm (EST).

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.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

or www.fadingforests.org

Help Ensure Best Pest-Countering Programs Possible!

This blog asks YOU!!! to support funding for key USDA programs. Each is essential for protecting the resilience of the Nation’s forests in the face of invasive pests. Please help by contacting your members of the House and Senate Appropriations Committees. I provide a list of members – by state – at the end of this blog.

While the two key federal programs overlap, they are separately managed: USDA’s Animal and Plant Health Inspection Service (APHIS) and USDA’s Forest Service (USFS). These two agencies are funded by different subcommittees of the House and Senate’s Appropriations committees. APHIS is funded by the Subcommittees on Agriculture and Related Agencies. USFS is funded by the Subcommittees on Interior.

Your letter or email need be no more than a couple paragraphs. To make the case for greater funding, feel free to pick-and-choose from the information that follows. Your greatest impact comes from speaking specifically about what you know and where you live.

These are the specific dollar things we’d like you to ask for. The rationale for each is below.

Appropriations for APHIS programs (in $millions)

ProgramFY 2021FY 2022  CRFY 2023 Pres’ requestPlease ask
Tree & Wood Pest$60.456$61.217$63 $70
Specialty Crops$196.553$209.553$219 $219
Pest Detection$27.733$28.218$29 $30
Methods Development$20.844$21.217$22 $23

Appropriations for USFS programs (in $millions)

ProgramFY 2021FY 2022  CRFY 2023 Pres’ requestPlease ask
Forest Health Protection Coop Lands$30.747 $30.747 $36,747$51
FHP Federal Lands $15.485 $15.485 $22.485 $32
Research & Development$258.760 $258.760 $317.773 $317.733
    % for forest invaders~1%??0$16 M

Background on the Threat

I’m sure you are familiar with the many ecosystem services provided by America’s forests and woodlands – wildland, rural, and urban. (Besides – maybe you just love trees!) I assume you also know that these forests are under threat from a growing number of non-native insects and pathogens.

For a quick review, see earlier blogs re: 1) an estimate that 41% of forest biomass in the “lower 48” states is at risk to mortality caused by the most damaging 15 species; black ash swamps of the upper Midwest; unique forest ecosystems of Hawai`i; riparian forests in the far West; stream canyons of the Appalachian range and; high-elevation forests of the West; and unique forests of Southwest Oregon.  Also, see the thorough discussion of these pests’ impacts in Invasive Species in Forests and Grasslands of the United States: A Comprehensive Science Synthesis for the United States Forest Sector – blog; link available here]

Meanwhile, newly-discovered pests continue to appear and require research and management. The most troubling current example is beech leaf disease. It’s killing beech trees from Ohio to Maine and south to Virginia.

These introduced pests usually first appear in cities or suburbs because they arrive on imported goods shipped to population centers. The immediate result is enormous damage to urban forests. A recently published article (“Hotspots of pest-induced US urban tree death, 2020–2050”), projects that, by 2050, 1.4 million street trees in urban areas and communities will be killed by introduced insect pests. Removing and replacing these trees is projected to cost cities $30 million per year. Additional urban trees – in parks, other plantings, on homeowners’ properties, and in urban woodlands – are also expected to die.

As we know, newly-arrived pests don’t stay in those cities. Some spread on their own. Others are carried far and wide on firewood, plants, patio furniture, even storage pods. And so they proliferate in rural and wildland forests, including US National Forests.

As we know too well, many pests—especially the highly damaging wood-borers—arrive in inadequately treated crates, pallets, and other forms of packaging made of wood. Other pests—e.g., spotted lanternfly —take shelter, or lay their eggs, in or on virtually any exposed hard surface, such as steel or decorative stone.

Imports from Asia have historically transported the most damaging pests. Unfortunately, imports from Asia have reached unprecedented volume – currently they’re running at a rate of 20 million shipping containers per year. Research findings lead to an estimate that at least 7,500 of these containers are carrying a tree-killing pest. The “Hotspots” authors found that if a new woodborer that attacks maples or oaks is introduced, it could kill 6.1 million trees and cost American cities $4.9 billion over 30 years. The risk would be highest if this pest were introduced to the South – and southern ports are receiving more direct shipments from Asia!  

Some types of pests—especially plant diseases and sap sucking insects —come on imported plants. A principle example is sudden oak death (SOD; and which attacks more than 100 species of trees and shrubs). Other examples are the rapid ʻōhiʻa death pathogen that threatens Hawai`i’s most widespread tree, ʻōhiʻa lehua; and beech leaf disease, a newly discovered threat that is killing beech trees in a band stretching from Ohio to Maine.

Background on Specific USDA Funding Requests

APHIS

To reduce the risk of new pest introductions and strengthen response to many important pests, please ask your member of Congress and Senators to support appropriations that support key APHIS programs in the table above. (I assume you know that APHIS is responsible for preventing introduction and spread of invasive pests. While most port inspections are carried out by the Department of Homeland Security’s Bureau of Customs and Border Protection, APHIS sets the policy guidance. APHIS also inspects imports of living plants.)

Thank your member for the incremental increases in funding for these programs in FY22 but suggest that a more substantial investment is warranted.  

The Tree and Wood Pests account supports eradication and control efforts targeting principally the Asian longhorned beetle (ALB) and spongy (formerly gypsy) moth. Eradicating the ALB normally receives about two-thirds of the funds. The programs in Massachusetts, New York, Ohio, and South Carolina must continue until eradication succeeds.

The Tree and Wood Pests account formerly also funded APHIS’ emerald ash borer (EAB) regulatory program. APHIS terminated this program in January 2021. The probable result is that EAB will spread more rapidly to the mountain and Pacific Coast states. Indeed, the “Hotspots” article identified Seattle and Takoma as likely to lose thousands of ash trees in coming decades. This result shows what happens when APHIS programs are inadequately funded.

Re: the plant diseases and sap sucking insects that enter the country on imported plants, APHIS’ management is through its Specialty Crops program. Repeatedly, SOD-infected plants and have been shipped from nurseries in the Pacific Coast states to vulnerable states across the East and South. Clearly this program needs re-assessment and – perhaps – additional funding.

The Specialty Crops program also is home to APHIS’ efforts to counter the spotted lanternfly, which has spread from Pennsylvania to Maryland, Delaware, New Jersey, Virginia, West Virginia, Ohio, even Indiana. This pest threatens both native trees and agricultural crops – including hops, grapes, apples, and more. California has adopted a state quarantine in hopes of preventing its introduction to that state. Still, APHIS has not established a quarantine.

Please ask the Congress to support the Administration’s request for $219 million for the Specialty Crops program. However, urge them to adopt report language to ensure that APHIS allots adequate funding under this budget line to management of both sudden oak death and spotted lanternfly.

Two additional APHIS programs are the foundation for effective pest prevention. First, the Pest Detection program is key to the prompt detection of newly introduced pests that is critical to successful pest eradication or containment. Please ask the Congress to fund Pest Detection at $30 million. Second, the “Methods Development” program enables APHIS to improve development of essential detection and eradication tools. Please ask the Congress to fund Methods Development at $23 million.

Please ask your member of Congress to support the Administration’s request for a $50.794 million fund for management of emergencies threatening America’s agricultural and natural resources. This program includes a $6 million increase for work with the Climate Conservation Corps specifically targetting invasive species. Although the details are not yet clear, the program’s focus will be to improve surveillance and mitigation methods.

US Forest Service

The USFS has two programs critical to managing non-native tree-killing pests – Forest Health Management (or Protection; FHP) and Research and Development (R&D). FHP provides technical and financial assistance to USFS units (e.g., National forests and regions), other federal agencies, states, municipalities, and other partners to detect and manage introduced pests – including several that APHIS regulates and dozens that it does not. R&D funds efforts to understand non-native insects, diseases, and plants – which are usually scientific mysteries when they first are detected. Of course, this knowledge is crucial to effective programs to prevent, suppress, and eradicate the bioinvader. See the table at the beginning of the blog for specific funding requests for each program.

The Forest Health Management Program (FHP) has two funding streams: Federal Lands and Cooperative Lands (all forests under non-federal management, e.g., state and private forests, urban forests). Both subprograms must be funded in order to ensure continuity of protection efforts – which is the only way they can be effective. Some members of Congress prefer to focus federal funding on National forests. However, allowing pests to proliferate until they reach a federal forest border will only expose those forests to exacerbated threats. Examples of tree-killing pests that have spread from urban areas to National forests include the hemlock woolly adelgid, emerald ash borer, polyphagous and Kuroshio shot hole borers, sudden oak death, and laurel wilt disease. [All profiled here]

Adequate funding for FHP is vital to realizing the Administration’s goals of ensuring healthy forests and functional landscapes; supporting rural economies and underserved communities; enhancing climate change adaptation and resilience; and protecting biological diversity.

Please ask your Member of Congress and Senators to provide $51 million for work on non-federal cooperative lands. This level would partially restore capacity lost over the last decade. Since Fiscal Year (FY) 2010, spending to combat 11 specified non-native insects and pathogens fell by about 50%. Meanwhile, the pests have spread. Also, please ask your Member and Senators to support a $32 million appropriation for the Federal Lands subprogram for FY23 which is allocated to pests threatening our National forests directly.

A vital component of the FHP program is its leadership on breeding pest-resistant trees to restore forests decimated by pests. FHP’s Dorena Genetic Resource Center, in Oregon, has developed Port-Orford cedar seedlings resistant to the fatal root-rot disease. and blog. These seedlings are now being planted by National forests, the Bureau of Land Management, and others. In addition, pines with some resistance to white pine blister rust are also under development. The Dorena Center offers expert advice to various partners  engaged in resistance-breeding for Oregon’s ash trees and two tree species in Hawai`i, koa and ʻōhiʻa. and blog.

The USFS research program is well funded at $317 million. Unfortunately, only a tiny percentage of this research budget has been allocated to improving managers’ understanding of specific invasive species and, more generally, of the factors contributing to bioinvasions. Funding for research conducted by USFS Research stations on ten non-native pests decreased from $10 million in Fiscal Year 2010 to just $2.5 million in Fiscal Year 2020 – less than 1% of the total research budget. This cut of more than 70% has crippled the USFS’ ability to develop effective tools to manage the growing number of pests.

To ensure the future health of America’s forests, please ask your Member of Congress and Senators to request the Subcommittee to include in its report instructions that USFS increase the funding for this vital research area to 5% of the total research budget. The $16 million would fund research necessary to improving managers’ understanding of invasive forest insects’ and pathogens’ invasion pathways and impacts, as well as to developing effective management strategies. Addressing these threats is vital to supporting the Administration’s priorities of increasing adaptation and resilience to climate change and implementing nature-based solutions.

The USFS Research and Development program should expand its contribution to efforts to breed trees resistant to non-native pests; programs deserving additional funding include hemlocks resistant to hemlock woolly adelgid; ashes resistant to emerald ash borer; beech resistant to both beech bark disease and beech leaf disease; link to DMF and elms resistant to Dutch elm disease. The Research program also continues studies to understand the epidemiology of laurel wilt disease, which has spread to sassafras trees in Kentucky and Virginia.

Members of House Appropriations Committee

STATEMEMBERAPHIS APPROPUSFS APPROP
ALRobert AderholtX 
CalifBarbara Lee
David Valadao
Josh Harder		X
X  		   

X
FLDebbie Wasserman       ScultzX   
GASanford BishopX 
IDMike Simpson X
ILLauren UnderwoodX 
MDAndy HarrisX 
MEChellie PingreeXX
MIJohn MoolenaarX 
MNBetty McCollumXX
NVSusie Lee
Mark Amodei		 X
X
NYGrace MengX 
OHMarcy Kaptur
David Joyce		 X
X
PAMatt Cartwright X
TXHenry CuellarX 
UTChris Stewart X
WADan Newhouse
Derek Kilmer		X
X
WIMark PocanX 

Members of Senate Appropriations Committee

STATEMEMBERAPHIS APPROPUSFS APPROP
AKLisa Murkowski X
CalifDiane FeinsteinXX
FLMarco Rubio X
HIBrian SchatzX 
INMike BraunX 
KSJerry MoranX 
KYMitch McConnellXX
MDChris Van Hollen X
MESusan CollinsX 
MSCindy Hyde-SmithXX
MORoy BluntXX
MTJon TesterXX
NDJohn HoevenX 
NMMartin HeinrichXX
ORJeff MerkleyXX
RIJack Reed X
TNBill Hagerty X
VTPatrick LeahyXX
WVShelly Moore Capito X
WITammy BaldwinX 

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.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

SOD – Frightening Genetics

tanoak killed by SOD; photo by Joseph O’Brien, via Bugwood

I am belatedly catching up with developments regarding sudden oak death (SOD; Phytophthora ramorum). The situation is worsening, with three of the four existing strains now established in U.S. forests. Nursery outbreaks remain disturbingly frequent.

This information comes primarily from the California Oak Mortality Task Force’s (COMTF) newsletters posted since October; dates of specific newsletters are shown in brackets.

Alarming presence of variants & hybridization

The long-feared risk of hybridization among strains has occurred. Canadian authorities carrying out inspections of a British Columbia nursery found a hybrid of European (EU1) and North American (NA2) clonal lineages. These hybrids are viable, can infect plants and produce spores for not only long-term survival but also propagation. So far the hybrid has been found in a single nursery; it has not spread to natural forests. The pathogen is considered eradicated in that nursery, so it is hoped it cannot reproduce further. [December 2021 newsletter, summarizing research by R. Hamelin et al.]

Noted British forest pathologist Clive Brasier warned in 2008 about the risk of hybrids evolving in nurseries which harbor multiple strains of related pathogens. (See full citation at end of the blog.)

The threat is clear: three of the four known variants are already established in forests of the Pacific Northwest – NA1, NA2, and EU1. (For an explanation of P. ramorum strains and mating types, go here.)

In Oregon, the EU1 strain was detected in a dying tanoak (Notholithocarpus densiflorus) tree in the forests of Curry County in 2015. Genetic analysis revealed that the forest EU1 isolates were nearly identical to EU1 isolates collected in 2012 from a nearby nursery during routine monitoring. This detection was considered to be evidence that multiple distinct P. ramorum introductions had occurred. The scientists expressed concern that the presence of this strain – which is of the A1 mating type while the widely established NA1 population of the pathogen in the forest is of the A2 mating type — makes the potential for sexual recombination more likely. Therefore, the state prioritized eradication of the EU1 forest infestation [Grünwald et al. 2016]. (For an explanation of P. ramorum strains and mating types, go here.)

The NA2 strain was detected in 2021, 33 km north of the closest known P. ramorum infestation. Because Oregonians genotype all detections on the leading front of the infection, they completed Koch’s postulates and found this surprising result [February 2022]. NA2 is thought to be more aggressive than the NA1 lineage [February 2022]. Surveys and sampling quickly determined that the outbreak is well established — 154 positive detections [February 2022] across more than 500 acres [October 2021]. Oregon Department of Forestry immediately began treatments; the goal is to prevent overlap with existing NA1 and EU1 populations. [April 2022; summarizing research by Peterson et al.] Given the number of infected trees and the new variant, Oregon pathologists believe this to be a separate introduction to Oregon forests that has been spreading in the area for at least four years [February 2022].

Scientists [April 2022; summarizing research by Peterson et al.] again note evidence of repeated introductions of novel lineages into the western US native plant communities; this region is highly vulnerable to Phytophthora establishment, justifying continued monitoring for P. ramorum not only in nurseries but also in forests.

SOD in Oregon; photo by Oregon Department of Forestry

The EU1 strain is also present in northern California, specifically in Del Norte County. It was detected there in 2020. Despite removal of infected and nearby host trees (tanoaks) and treatment with herbicide to prevent resprouting, the EU1 strain was again detected on tanoaks in 2021. The detected strain is genetically consistent with the EU1 outbreak in Oregon forests. Oddly, the usual strain found in North American forests, the NA1 strain, was not detected in Del Norte Co. in 2021 [February 2022].

One encouraging research finding [April 2022; summarizing research by Daniels, Navarro, and LeBoldus] is that established treatment measures have had significant impact on both the NA1 & EU1 lineages. They found on average 33% fewer positive samples at treated sites where NA1 is established; 43% reduction in P. ramorum prevalence at EU1 sites. Prevalence of P. ramorum in soil was not affected by treatment.

SOD Spread in Forests

In California, the incidence of new Phytophthora ramorum infections fell in 2021 to a historic low – estimated 97,000 dead trees across 16,000 acres, compared to ~885,000 dead trees across 92,000 acres in 2019 [April 2022]. It is agreed that the reason is the wave of mortality sparked by the very wet 2016-2017 winter has subsided and has been followed by several years of drought [February 2022].

data showing decline in new SOD detections in California in 2021 (no data collected in 2020)

In Oregon, however, SOD continues to spread. In 2010, the OR SOD Program had conceded that eradication was no longer feasible. Instead, authorities created a Generally Infested Area (GIA) where removal of infested tanoaks was now optional (not mandated) on private and state-owned lands. Since then, SOD has continued to spread and intensify within the designated zone. The GIA has been expanded eight times since its establishment in 2012; it now it covers 123 sq. mi. There has also been an immediate increase in tanoak mortality [December 2021].

In 2021, two new infestations were detected outside the GIA. One outbreak is on the Rogue River-Siskiyou National Forest along the Rogue River, 6 miles north of any previously known infestation. The second is just outside Port Orford [February 2022], 33 km north of the closest known infestation. This second infestation is composed of the NA2 variant [see above]. The Oregon Department of Agriculture (ODA) established emergency quarantines at these sites and began eradication efforts at both sites. The Oregon legislature appropriated $1.7 million to Oregon Department of Forestry to carry out an integrated pest management program to slow spread of the disease [February 2022].

Scientific research indicates that this situation might get worse. While it has long been recognized that California bay laurel (= Oregon myrtle) (Umbellularia californica) and tanoak are the principal hosts supporting sporulation and spread, it has now been determined that many other native species in the forest can support sporulation. Chlamydospore production was highest on bigleaf maple (Acer macrophyllum)and hairyCeanothus (Ceanothus oliganthus). All the other hosts produced significantly fewer spores than tanoak and myrtle [October 2021; summarizing research by Rosenthal, Fajardo, and Rizzo]

Furthermore, studies that aggregate observations of disease on all hosts, not paying attention to their varying levels of susceptibility, might lead scientists to misinterpret whether the botanic diversity slows spread of the pathogen [October 2021 summarizing research by Rosenthal, Simler-Williamson, and Rizzo].

Monitoring to detect any possible spread to the East

SOD risk map based on climate & presence of host species; USFS

The USDA Forest Service continues its Cooperative Sudden Oak Death Early Detection Stream Survey in the East. In 2021, 12 states participated – Alabama, Florida, Georgia, Illinois, Maryland, Mississippi, North Carolina, Pennsylvania, South Carolina, Texas, West Virginia, and Wisconsin. Samples were collected from 79 streams in the spring. Two streams were positive, both in Alabama. Both are associated with nurseries that were positive for P. ramorum more than a decade ago [October 2021].

Continued infestations in the nurseries

USDA Animal and Plant Health Inspection Service (APHIS) reported that in 2021, the agency supported compliance activities, diagnostics, and surveys in nurseries in 22 states. P. ramorum was detected at 17 establishments. Eight were new; nine had been positive previously. These included seven nurseries that ship intrastate – all had been positive previously. Six were already under compliance agreements. Also positive were three big box stores – none previously infected; and six nurseries that sell only within one state – five new. Infections at the big box outlets and half the intrastate nurseries were detected as a result of trace-forwards from other nurseries.

P. ramorum was detected in 300 samples in 2021 – 144 from plants in the genus Viburnum; 106 from Rhodendron (including azalea); and much lower numbers from other genera.

APHIS funds states for annual nursery surveys, compliance activities, and diagnostics through the: Plant Protection Act Section 7721 and the Cooperative Agricultural Pest Survey (CAPS) program. Table 4 lists states receiving survey funds. APHIS also supported compliance and diagnostic activities in California, Louisiana, Oklahoma, Oregon, Pennsylvania, Washington, and several states through Florida.

APHIS’ report – which provides few additional  details about the nursery  detections – can be found here.

California:

The California Department of Food and Agriculture (CDFA) reported that three of the eight nurseries regulated under either the federal or state sudden oak death program tested positive in 2021. This was down from five positive nurseries in 2020 [February 2022]. (In the past, numbers of nurseries testing positive have declined during droughts, risen during wet years.) At one interstate-shipping nursery 145 positive Viburnum tinus plants were detected by regulators in December 2021. Apparently the detection efforts were prompted by a trace-back from a nursery in an (unnamed) other state [April 2022].

Oregon:

Oregon continues to struggle with the presence of Phytopththora ramorum in the state’s nurseries. Early in 2021 the situation looked good. Three of eight interstate shippers and two intrastate shippers “passed” their sixth consecutive inspection with no P. ramorum detected so they were released from state and federal program inspection requirements. A fourth interstate-shipping nursery had ceased operating. By the end of the year, however, circumstances had deteriorated. One of the four interstate shippers still under regulatory scrutiny appeared to be badly infested. After routine autumn monitoring detected an infected plant, subsequent delimitation samplings detected 30 additional positive foliar samples and a large number (24) of samples were inconclusive. By spring 2022 six nurseries had to be inspected following trace-forwards from out-of-state nurseries. No P. ramorum was detected in five of these nurseries; the sixth had one positive foliar sample, so it is now under more stringent regulatory supervision [April 2022].

Washington:

Washington has only one interstate shipping nursery that is regulated under APHIS’ program; it tested negative in autumn 2021 [December 2021]. Meanwhile, USDA & Washington Department of Agriculture (WSDA) decided to deregulate the Kitsap County Botanical Garden where P. ramorum had been detected in 2015. Since then, more than 5,000 samples have been collected; 99.1% have tested negative. The last positive plant sample was collected in February 2016. Under a compliance agreement, the botanical garden will continue the best management practices deemed successful in eradicating the pathogen [December 2021]. However, water at the site continues to test positive [February 2022]. These water detections – in Washington and Alabama (above) – raise troubling questions.

Meanwhile, in late winter [April 2022], WSDA had to conduct two trace-forward investigations on plants that shipped from (unnamed) out-of-state nurseries. As of the April newsletter, 13 samples from four locations were all negative.

A stubborn problem has been the persistence of SOD infections in nurseries after the Confirmed Nursery Protocol has been carried out. Research indicates the reason might be that the pathogen is still there in the form of soilborne inoculum in buried, infested leaf debris [December 2021 newsletter; summarizing research by Peterson, Grünwald, and Parke].

Another native tree identified as host

photo by Miguel Vieira; via Wikimedia

Dieback on golden chinquapin, Chrysolepis chrysophylla, a slow growing, evergreen tree native to the U.S. west coast has been confirmed as caused by Phytophthora ramorum. The detection was in a part of Marin County, California heavily infested by P. ramorum since early in the epidemic. Affected trees were large overstory trees. Unlike other hosts in the Fagaceae, there were no external bole cankers [April 2022 newsletter; summarizing research by Rooney-Latham, Blomquist, Soriano, and Pastalka].

SOURCES

Brasier, C.M. 2008. The biosecurity threat to the UK and global environment from international trade in plants. Plant Pathology (2008) 57, 792-808

Grunwald, N.J., M.M. Larsen, Z.N. Kamvar, P.W. Reeser, A. Kanaskie, J. Laine and R. Wiese. 2016. First Report of the EU1 Clonal Lineage of Phytophthora ramorum on Tanoak in an Oregon Forest. Disease Notes. May 2016, Vol. 100, No. 5, p. 1024

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.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

Harvest + Tree-Killing Pests = Threat to Forest Composion

EAB-killed ash in Ontario; photo by Michael Hunger

Lately I have become aware of articles discussing how silviculturists and timber managers in the East are responding to the threat from introduced pests.

As Holt et al. (2022; full citation at end of blog) point out, private landowners control 56% of U.S. forestland – and 80% in the East. Their collective decisions about managing those forests are one of two factors that largely determine the composition and structure of the forested landscape and the ecosystem services those woodlands provide. The second determining factor is invasive pests. If an invasive pest prompts many landowners across the East to harvest their timber, the collective impact will be enormous. In this way, invasive species carry a double threat: direct mortality of one or more tree species or genera; and stimulation of removal of the host species from the forest by land managers trying to maximize or protect their current and future monetary investment.

Projections suggest that the number of non-native woodborers established in North America will increase three- or four-fold by 2050. If these prove true (see Leung et al. 2016), the impact on eastern North America forests and associated ecosystem services would be profound.

Holt et al. explore how private landowners have responded to an actual invasive species, the emerald ash borer (EAB). They analyze the influence of EAB’s presence on:

(1) annual probability that a landowner would decide to harvest timber on his/her own lands;

(2) intensity of any such harvest (percentage of trees cut); and

(3) diameter of harvested trees.

They examined harvesting of both the host (ash) and non-host species that co-occur.

Using data from U.S. Forest Service permanent inventory plots, they compared harvest levels in counties in which EAB was detected before 2007 to harvest levels in counties that were infected after 2012. To simplify, they omitted counties in which EAB was detected during the period 2007–2012. They excluded plots that did not contain any ash trees; and plots owned by federal or state agencies. They also excluded trees with diameters less than 12.7 cm (5 inches) dbh.

Ash harvests were apparently less widespread than non-ash harvests. Ash trees were harvested on 6% of the USFS Forest Inventory and Analysis (FIA) plots compared to 9% of plots for harvests of non-ash trees. However, a higher proportion of ash basal area was removed in these harvests — 63% of ash basal area versus 32% of non-ash basal area (remember, ash trees were present in all plots).  

The presence of EAB resulted in

  • an increased amount of biomass harvested – by approximately 25% of basal area;
  • harvests contained greater quantities of ash, relative to non-ash species.
  • harvested trees in EAB-infested areas had smaller diameters, on average; this was true of both ash and non-ash species.

Two demographic variables were analyzed. Higher median household income resulted in a lower probability of non-ash harvest. Human population density had no significant effect.

Holt et al. say their findings indicate that a wave of ash removals will follow EAB spread with a potential to alter forest development trajectories and change structural legacies, with consequences for ecosystem services and biodiversity. They consider tree species that co-occur with ash, and that are preferred timber species, are the most likely to be removed in excessive numbers as a result of EAB-induced harvest.

Holt et al. note that ash removals were perhaps underestimated by the study because landowners might have cut their ash before EAB actually was detected in their county.

Managing the Northern Forest – Emphasis on reducing the beech component

Meantime, two other groups are suggesting how forest managers should respond to current challenges, including invasive pests. Both suggest steps to reverse – or at least slow – trends under which American beech (Fagus grandifolia) is becoming more dominant. (Given beech’s ecological importance, this stance bothers me!  I don’t quarrel that many timber-oriented people don’t want more beech.) Neither of these studies considers the possible impact of beech leaf disease and beech leaf miner.  I recently posted a blog link reporting Reed et al.’s (2022) analysis of interactions between BBD and BLD.

Rogers et al. (2022), the first group, note that successful silviculture is the art and science of managing forests intended to achieve human defined goals. Usually this means assuring the “desired” species composition and structure. However, to succeed, silviculture must also consider site conditions, including competing vegetation and changing climates.

They focus on the northern hardwood forest – also called the beech-birch-maple forest. It is broadly defined by the dominance of sugar maple (Acer saccharum), yellow birch (Betula alleghaniensis), and American beech. The northern hardwood forest occupies about 20 M ha across northern United States and southern Canada. From a traditional management perspective, maple and birch are the desired species; American beech is widely considered undesirable.

Unfortunately, from the timber point of view, Rogers et al. expect the abundance of sugar maple and yellow birch to decrease and American beech to increase. Important factors in this trend are soil types; deer numbers and preference for tree species other than beech; and high number of root sprouts stimulated by beech bark disease (BBD). Rogers et al. call for modification of traditional silvicultural approaches in the region. They call specifically for “adaptation planting” (also called “assisted migration”). They note that increased canopy openings – e.g., “irregular shelterwood system” — are important for establishing shade intolerant and mid-tolerant species, among them white ash (Fraxinus americana). They do mention the threat from emerald ash borer.

In an earlier blog I noted that the second group, Clark and D’Amato(2021), called for silvicultural management of New England forests (part of the same northern hardwood forest). Their goal was to maximize carbon sequestration. They advised management to promote retention of eastern white pine (Pinus strobus) and slow takeover by American beech and eastern hemlock (Tsuga canadensis). They say these species will fare poorly in warmer climates. Of course, all these species face non-native pests. See above for beech; hemlock is being decimated by hemlock woolly adelgid. Eastern white pine has apparently survived its own non-native pest, white pine blister rust.

I hope these pest-related hindrances to traditional timber-focused forestry will help convince the U.S. Department of Agriculture and Congressional agriculture and natural resource committees that non-native pests are a significant threat. Clearly past documentation of impacts to biological diversity and native ecosystems have not prompted them to adopt adequate protective measures or to respond effectively to established invaders. See earlier blogs, my recent article, and the Fading Forests reports (link at end of blog) for suggestions on what actions should be taken.

SOURCES

Clark, P.W. and A.W. D’Amato. 2021. Long-term development of transition hardwood and Pinus strobus – Quercus mixedwood forests with implications for future adaptation and mitigation potential. Forest Ecology and Management 501 (2021) 119654

Holt, J.R., J.R. Smetzer, M.E. Borsuk, D. Laflower, D.A. Orwig, J.R. Thompson. 2022. EAB intensifies harvest regimes on private land. Ecological Applications. 2022;32:e2508.

Leung, B., M.R. Springborn, J.A. Turner, E.G. Brockerhoff. 2014. Pathway-level risk analysis: the net present value of an invasive species policy in the US. The Ecological Society of America. Frontiers of Ecology.org

Rogers, N.S., AW. D’Amato, C.C. Kern, S. B`edardd. 2022.  Northern hardwood silviculture at a crossroads: Sustaining a valuable resource under future change

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.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

APHIS – 50 years + plant pest detection month

beech leaf disease – Not one of the plant pests that APHIS is regulating! Photo by Jennifer Koch, USFS

APHIS has reminded us that 2022 is the agency’s 50th year. In its press release, APHIS claims several accomplishments over this period:

  • Eradicating plant pests like European grapevine moth and plum pox from the country, while reducing the impact of others plant diseases, including boll weevil and Mediterranean and Mexican fruit flies;
  • Eradicating serious animal diseases, including highly pathogenic avian influenza, virulent Newcastle disease, and pseudorabies, from the country’s herds and flocks, while reducing the prevalence of other animal diseases like bovine tuberculosis and brucellosis;
  • Improving care for laboratory animals, exhibited animals and other animals;
  • Ensuring genetically engineered plants do not pose a risk to plant health, while keeping up with the ever-changing technology in this field;
  • Reducing the impact of wildlife damage on agriculture and natural resources; and
  • Ensuring safe trade of agriculture commodities across the globe

APHIS also launched a new page on its website to share a series of visual timelines of its history and important milestones.

APHIS also states that USDA) has declared April 2022 to be Invasive Plant Pest and Disease Awareness Month (IPPDAM). The link Invasive Plant Pest and Disease Awareness Month connects you to APHIS’ webpage. Secretary Vilsack asks people to be alert. He noted particularly the risk that pests will hitch a ride on untreated firewood, outdoor gear and vehicles, and soil, seeds, homegrown produce, and plants.

The notice urges people to:

  • Familiarize yourself with the invasive pests that are in your area, and their symptoms. [Faith says – also look for pests not “here” yet – early detection!]
  • Look for signs of new invasive plant pests and diseases and report them to your local Extension office, State department of agriculture or your USDA State Plant Health Director’s office.
  • When returning from travel overseas, declare all agricultural items to U.S. Customs and Border Protection so they can ensure your items won’t harm U.S. agriculture or the environment.
  • Don’t move untreated firewood. Buy local or use certified heat-treated firewood, or responsibly gather it on site where permitted.
  • Source your plants and seeds responsibly. When ordering online, don’t assume items available from foreign retailers are legal to import into the United States. Learn how to safely and legally order plants and seeds online.
  • Don’t mail homegrown plants, fruits and vegetables. You may live in an area under quarantine for a harmful invasive plant pest. You could inadvertently mail a pest.
  • When in doubt, contact your local USDA State Plant Health Director’s office to find out what you need to do before buying seeds or plants online from an international vendor or before mailing your homegrown agricultural goods.

West Coast Responding to EAB

nearly pure stand of Oregon ash in Ankeny National Wildlife Refuge, Oregon; photo by Wyatt Williams, Oregon Department of Forestry

While Michiganders document the impacts of the emerald ash borer (EAB) there, conservationists on the West Coast are jump-starting efforts to save their regional species, Oregon ash (Fraxinus latifolia). Earlier field tests in the Midwest showed that EAB will attack Oregon ash (press release) – something West Coast state would like to counter as early and effectively as possible.

Oregon ash is a wide-ranging species, occurring from California to Washington and possibly into British Columbia. The species has not been studied extensively (it is not a timber species!), but it is clearly an imponearlrtant component of riparian forests. In wetter parts of the Willamette Valley, ash is the predominant tree species. See the photo of the riparian forest in the Ankeny National Wildlife Refuge; this forest is nearly 100% Oregon ash (ODA/ODF EAB Response Plan).

As is true in the Midwest, ash provides important food and habitat resources along creeks and rivers where seasonally high water-tables can exclude nearly all other tree species. Standing and fallen dead ash biomass can alter soil chemistry and affect rates of decomposition, nutrient, and water cycling, i.e., nutrient resource availability for the remaining trees. Gaps in tree canopy can increase soil erosion, stormwater runoff and elevated stream temperatures. In dense stands of Oregon ash, understory vegetation is often sparse, consisting primarily of sedges. The authors of the Response Plan anticipate invasion by non-native plants into canopy gaps caused by the loss of ash trees as a result of an EAB invasion. In Michigan, though, it is the sedges that dominate these gaps.

The Oregon Department of Forestry, the state Department of Agriculture, and other entities have actively participated in “don’t move firewood” campaigns for at least a decade. The Departments of Forestry and Agriculture also led a team that prepared the EAB Response Plan in 2018 (full citation at the end of this blog). It lays out in considerable detail the roles of both government agencies and non-governmental stakeholders. Oregon’s quarantine is broad, covering all insects not on an approved list (Williams, pers. comm.)

California has inspected incoming firewood for years. In April 2021 – after APHIS terminated the federal quarantine on EAB — California Department of Food and Agriculture established a state quarantine on the beetle and articles that could transport it into the state. In doing so, CDFA noted that commercially grown olive trees might also be at risk to EAB.

Washington State operates a statewide trapping program for invasive insects. There has also been significant attention to non-native insect threats to urban forests. These have included a study in 2016 led by the Washington Invasive Species Council (WISC). It involved a partnership of WISC with the Washington Department of Natural Resources Urban and Community Forestry Program as well as and statewide stakeholder meetings [Bush, pers. comm.].

Of these various state-wide initiatives, the institutions in Oregon appear to be most pro-active. The Tualatin Soil and Water Conservation District provided $10,000 to fund some of the genetics work and testing for EAB resistance. Other funding came from the USDA Forest Service Forest Health Protection unit of State and Private Forestry (not from USFS’ Research Program). As described by USFS geneticist Richard Sneizko in an article in the publication TreeLine (full citation at end of blog), participants hope to find at least some level of genetic resistance to EAB. Any such resistance might be deployed in several ways: 1) promoting reproduction by resistant trees to enhance their numbers before EAB gets to Oregon; 2) using seeds from resistant trees for restoration of natural areas; or 3) cross-breeding resistant trees to build genetically diverse stocks of resistant trees for future restoration.

Participants think it is vitally important to work from seeds collected over much of the range of Oregon ash – first, to search for probably very rare resistant trees; and second, to preserve the full diversity of the tree species’ genome so that restored ash will be adapted to the wide variety of conditions in which ash grow.

Participants in this effort include the forest genetics/tree improvement community – specifically, the USDA Forest Service Dorena Genetic Resource Center (located in Cottage Grove, Oregon) and Washington State University at Puyallup Research & Extension Center. Also engaged is the public gardens community, specifically the Huntington Botanical Gardens in San Marino, Los Angeles County.  The garden is collecting seed of Oregon and other western ashes from California and Washington State.

The first step in assessing resistance is collecting seed from ash trees across the range of Oregon ash. This began in 2019. Carried out by, inter alia, some USFS and Interior’s Bureau of Land Management units, Oregon State University, citizen scientists [Sniezko] and the Oregon Department of Forestry [press release & Sniezko pers. comm.] Also, some seeds were collected in Washington State in 2020. Additional collections in Oregon are scheduled for 2022.

The collected seeds have been evaluated for vitality and stored by the USFS Dorena Center and at the USFS National Seed Lab (Macon, GA).

Oregon ash planting at Dorena; photo by Emily Boes

The USFS Dorena Center and Washington State University have begun germinating and growing some of the seedlings for various tests of possible resistance. There is concern that the 2021 drought might have killed some of the seedlings in Oregon; those in Washington are not affected. The initial seedlings are mostly from Oregon but there is space to add additional families from a wider geographical area. Experimenters plan to collect data annually on bud break, yearly growth, and any diseases or pests that develop on the trees. (Chastagner pers. comm.)

The next step is systematic testing whether some of the ash show genetic resistance to EAB. Richard Sneizko has sent seedlings of 17 ash families to USFS colleague Dr. Jennifer Koch. She operates a breeding facility in northern Ohio where they can be tested for resistance. Testing is expected to begin this year. [Tree Line]

The Dorena Center is also helping a researcher at Penn State University, Dr. Jill Hamilton, to set up a landscape genomics project. She will evaluate the genetic variability in the species by using leaf samples from about 20 trees from many populations across the Oregon ash’s range (California to British Columbia).  This potentially includes a collection from the Dorena population of ash in late Spring 2022. [Sniezko]

These various ash plantings can also be “sentinel” plantings to assist in early detection of newly arriving EAB. [Tree Line]

SOURCES

Bush J. Executive Coordinator | Washington Invasive Species Council

ODF and ODA Emerald Ash Borer Readiness and Response Plan. 2018. 

Click to access EAB+Plan+2018.pdf

ODF press release Feb 24, 2022

Treeline Newsletter May 13, 2021. Richard Sniezko. Is There a Future for Oregon Ash? Forest Genetics to the Rescue? Genetic & Emerald Ash Borer Resistance Projects https://www.nnrg.org/wp-content/uploads/2022/02/Treeline_newsletter-June-2021.pdf

The newsletter is issued by Bonneville Environmental Foundation for a consortium of conservation agencies

Sniezko pers comm Feb 2022  22-2/24

A video explaining the campaign to save Oregon ash is at https://youtu.be/uZmfLrxEA7g or https://youtu.be/S8y-XK285S8

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.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm