They’re coming! As I have blogged frequently over the past year, imports through ports other than Los Angeles-Long Beach are rising – and with them the risk of pest introductions.
Demonstrating this phenomenon is the fact that the largest container ship ever to call on the North American East Coast will arrive this week. The “Marco Polo” can carry 16,022-TEU (twenty-foot equivalent; a standardized measure of container capacity). It is scheduled to call at Nova Scotia today (May 17), then work its way down the coast to New York-New Jersey on May 20, Norfolk on May 23, Savannah on May 26, and Charleston on May 28. Most of these ports have a history of receiving tree-killing pests: beech bark disease, beech leaf weevil, and brown spruce longhorned beetle at Halifax, NS; Asian longhorned beetle at New York and possibly Charleston; redbay ambrosia beetle at Savannah.
The ship’s owner CMA CGM (a French company operating around the globe), also holds the previous record for the largest ship to visit the east Coast: the 15,072-TEU “Brazil” called at New York-New Jersey in September 2020. CMA CGM North America President Ed Aldridge credited the ports’ significant increases in capacity for allowing the increased volume.
CMA CGM is focused on imports from the Indian Subcontinent and Southeast Asia. Ships headed to the North American East Coast are transitting the Suez Canal.
CMA CGM also operates the “Jules Verne” with a capacity of 16,022-TEU; and the “Ben Franklin” at 18,000-TEU. These ships serve trans-Pacific trade.
During the first 10 months of 2020, 15% of vessel calls were by ships with capacities of 10,000-TEU or higher, up from 11% in 2019.
I am alerting you to two publications about our “favorite” tree-killing pathogen, Phytopthora ramorum (sudden oak death).
SOD-infected rhododendron in a nursery in Indiana; photo by Indiana Department of Natural Resources
The Role of Nurseries in Spreading SOD
The first article informs the general public and raises important questions: “The Diseased Rhododendrons That Triggered a Federal Plant Hunt” by Ellie Shechet in The New Republic.
Ellie reviews the 2019 episode in which P. ramorum-infected rhododendron plants were shipped to retailers in the East and Midwest. Her article is based on interviews with state plant health and APHIS officials, several scientists and advocates (including me), and the executive director of the Oregon Association of Nurseries (OAN). Ellie notes that infected plants were found at more than 100 locations across 16 states.
Ellie notes that despite the risk to native plants in the eastern deciduous forest and the financial cost of implementing control actions (14 million plants were inspected in Washington State alone), plants have a “green” reputation; they are not recognized as potentially causing environmental harm.
The politics of the situation also are reviewed. She writes that the OAN representative has testified that he helped write the more relaxed regulatory approach that APHIS adopted by “federal order” in 2014 and formalized in changes to the regulations in 2019. APHIS denies this. [The article does not include the information that during this period, state regulatory officials detected P. ramorum-infected plants in between four and ten Oregon nurseries each year.] Ellie notes that individual consumers buying plants have few tools to try to ensure that plants they buy are not infected by SOD or other pathogens.
The fact is that the climate in the coastal areas of California, Oregon, Washington, and British Columbia is conducive to SOD, so the risk of diseased plants being produced there and sold is constant. The current APHIS regulations do not adequately address this, in my view!
Science: High Risk of Phytophthora Introductions from Southeast Asia
The second article reports results of intense scientific effort: Thomas Jung, Joan Webber, Clive Brasier, and other European plant pathologists report more completely on searches for P. ramorum and other Phytophthora species in East Asia. See the full citation at the end of this blog. [I blogged about their preliminary report a little over a year ago.] Jung et al. conclude that P. ramorum probably originates from the laurosilva forests growing in an arc from eastern Myanmar, across northern Laos, Vietnam, and southwestern China (Yunnan) to Shikoku & Kyushu islands in southwest Japan. The article notes that two other Phytophtoras – P. lateralis (cause of fatal disease on Port-Orford cedar) and P. foliorum – appear to be from the same area. Field science by this team has found 38 previously unknown Phytophthora species in these same forests – and expect that more are present.
Clive Brasier in Vietnam; UK Forestry Research
They warn that the lack of information about potential pathogens in many developing countries presents a high risk of introduction to naïve environments through burgeoning horticultural trade – especially since the World Trade Organization requires that a species be named and identified as posing a specific threat before phytosanitary regulations can be applied. [I addressed the issue of international phytosanitary rules in Fading Forests II; see the link at the end of the blog.]
Other Pathogen Risks from the Region
Phytophthoras transported on imported plants are not the only pathogens that could come from Asia. The vectors and associated pathogens causing laurel wilt disease across the Southeast and Fusariumdisease in California are believed also to originate in the same region of Asia. Unlike the Phytophthoras, which are transported primarily through the trade in plants for planting, these fungi travel with the vector beetles in wood packaging material. U.S. imports of goods from Asia – often packaged in wooden crates or pallets – have skyrocketed since July 2020. The ports of Los Angeles-Long Beach, which receive 50% of U.S. imports from Asia, handled 6.3 million TEU (twenty-foot equivalent containers) from Asia during the period July 2020 through February 2021. The average of close to 800,000 TEU per month for eight consecutive months is unprecedented. Other ports also saw increased import volumes from Asia during this period. [I discussed these shifts in my blog in January.] Imports from Asia in 2020 accounted for 67.4% of total US imports from the world. Imports from China specifically accounted for 42.1% of total US imports. [Data on import volumes is from several reports posted by the Journal of Commerce at its website: https://www.joc.com/maritime-news/]
SOURCE
Jung, T.; Horta Jung, M.; Webber, J.F.; Kageyama, K.; Hieno, A.; Masuya, H.; Uematsu, S.; Pérez-Sierra, A.; Harris, A.R.; Forster, J.; et al.. The Destructive Tree Pathogen Phytophthora ramorum Originates from the Laurosilva Forests of East Asia. J. Fungi 2021, 7, 226. https://doi.org/10.3390/ open access!
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
Lymantria monacha 1 Novlinder, Saxafraga -Ab H Bass
The North American Plant Protection Organization (NAPPO) has released a scientific study, Risks Associated with the Introduction of Exotic Tussock Moth Species (Lepidoptera: Erebidae: Lymantriinae) of Potential Concern to the NAPPO Region.
The report identifies 13 species of tussock moths — other than several Asian gypsy moths – that pose a serious risk to Canada, Mexico, and the United States and that should be addressed as quarantine pests. However, vital information was missing in key areas, on one variable for more than 84% of the 79 species screened. Thus many additional species were not fully evaluated; some of these might also pose serious risks. Study findings
North American countries already regulate several species of Lymantria native to east Asia: Lymantria dispar asiatica, L. dispar japonica, L. albescens (includes L. postalba), and L. umbrosa. NAPPO’s Regional Standard for Phytosanitary Measure (RSPM) No. 33urlsets up a system requiring inspection and cleaning of marine vessels travelling from China, Korea, and Russia to the NAPPO region during the specified risk periods (SRP) of moth flight and egg mass deposition by these species.
However, the U.S. and Canada have been intercepting egg masses belonging to other lymantriid species, especially Lymantria lucescens, Leucoma salicis, Lymantria mathura, and Lymantria xylina. In response, the NAPPO countries initiated this study. All life stages — egg masses, larvae, pupae, and adults — have been intercepted in the NAPPO region primarily during maritime port inspections of vessels and shipping containers originating in Asia (Russia, Japan, China, Philippines, and Korea) and Europe.
There are more than 2,400 species of Lymantriids found on all continents except Antarctica. The group is also missing from Pacific islands, including New Zealand and Hawai`i. The greatest diversity occurs in the tropical areas of Africa, India, and Southeast Asia.
Lymantriid moths can have high fecundity, which can result in large population increases in a single generation. Some undergo cyclical outbreaks resulting in large-scale defoliation of their host plants.
The larvae are highly polyphagous. Some species feed on more than 150 hosts, especially trees – both deciduous and coniferous. The host plants are better known in temperate regions of the Northern Hemisphere; little is known about hosts of tropical moth species.
The study concluded that there is a high likelihood of introduction of lymantriid species into the NAPPO region due to the high volume of trade coming from Asia, the large number of probable lymantriid host species in North America, and the apparently suitable climatic conditions. While there are several possible pathways for transporting the moths from Asia to North America, the most important is the presence of masses of resilient eggs on surfaces of ships and hard-sided cargo (containers, motor vehicles, etc.). Once in North American ports, mated female moths can disperse either by flight (some species) or by “ballooning” on wind currents.
The authors initially collected data on 189 species. The report does not indicate whether they focused on Asia, but the results seem to be limited largely to that region. The authors winnowed the initial list down to 79 species for further analysis due largely to lack of resources and information. The Risk Assessment Model and Data Sheet are available here.
The study concluded that 13 species pose a high and that the NAPPO countries should designate them as “actionable pests” and take other actions to prevent their introduction. The high-risk species are Lymantria monacha, L. mathura, L. lunata and L. xylina, Euproctis kargalika, Euproctis subflava, Euproctis chrysorrhoea, Leucoma candida, Orgyia thyellina, Euproctis lunata, Leucom wltshirei, Lymantria fumida, and Sarsina violascens.
Evaluation Process
The 79 species were evaluated based on eight questions:
1) Are adult females attracted to light? (The authors thought such behavior would make them more likely to be flying during risk periods and attracted to ports and vessels).
2) Has the species been reported as a contaminant pest of commodities in trade in its
overwintering stage? (This presence was thought to result in species that are likely to move via trade and have the highest risk of survival and introduction).
3) Is the species reported to cause economic or environmental damage in its native range?
4) Does the species have larvae capable of ballooning?
5) Does the species have adult females capable of flight?
6) Does the species’ life history include a dormant stage able to withstand harsh environmental conditions? (Such species were thought to be more likely to survive transit to the NAPPO region and to persist once introduced).
7) Is the species capable of natural dispersal farther than 1 km/year?
8) Is the species reported to have allergenic properties?
Questions 2 & 3 were given more weight because they were considered to have a greater effect on the likelihood of the species being introduced and causing unacceptable impacts.
Weaknesses
Both the apparent focus on Asia and the emphasis on question 3 result in a process that was unlikely to uncover any potential pests that are currently “unknown unknowns”.
Vitally important information was missing for many of the species. For six of the eight questions, the evaluation found no information for more than 50 percent of the species evaluated. Information was lacking for Question 2 – one of the questions assigned greater weight – on 84 percent of the species! Ability to disperse more than 1 km per year had an even higher percentage of answers as “unknown”. Regarding “ballooning” of larvae, 80 percent of the species could not be classified.
These data gaps created a high level of uncertainty regarding the risk rankings of those species ranked as “low” risk. See Figure 2 from the report.
One of the reasons cited for the information gaps was the inability to access literature in foreign languages, specifically Russian. Surely both the U.S. and Canada have access to native Russian speakers!
The authors admit that the lack of information “affected the risk scores and possibly the risk categories for certain species.” They call for additional research and periodic reviews of the report’s findings.
They note that the report is a quick screening tool, not a rigorous pest risk assessment. They suggested additional research and sharing of interception data to address the information gaps. The research should focus on species’ flight periods and biological information relevant to regulatory actions; and detection tools (e.g., traps, lures, predictive phenology models, and molecular identification tools).
They note that the three countries currently limit surveillance and management programs to a few taxa.
I concur with the authors’ recommendation that a moth species be considered to pose a serious threat if it feeds on a host included in a tree or shrub genus that has economic value in the NAPPO region. (Under the terms of the International Plant Protection Organization, ISPM#5, environmental damage is included in the term “economic value”.)
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
Two USDA agencies lead efforts to protect U.S. wildland, rural, and urban forests from non-native insects and disease-causing pathogens:
USDA Animal and Plant Health Inspection Service (APHIS) has legal responsibility for preventing introduction of tree-killing pests, detecting newly introduced pests, and initiating eradication and containment programs intended to minimize the damage they cause.
USDA Forest Service (USFS)
Forest Health Management (FHM) program assists partner agencies to counter pests where they are first found – usually near cities – and when they spread. This work falls primarily to the Cooperative component of Forest Health Management program. The Federal lands component helps the USFS, National Park Service, and other federal agencies counter pests that have spread to more rural/wildland areas.
Research and Development (R&D) program supports research into pest-host relationships, introduction & spread pathways, management strategies (including biocontrol) and host resistance breeding
Since 2010, several new tree-killing pests have been detected in the US, including polyphagous and Kuroshio shot hole borers, spotted lanternfly, two rapid ʻōhiʻa death pathogens, and Mediterranean oak beetle. Over the same period. the Asian longhorned beetle has been detected in two new states – Ohio and South Carolina; the emerald ash borer expanded its range from 14 to 35 states; laurel wilt disease spread from five states to 11; a second strain of the sudden oak death fungus appeared in Oregon and California forests; and whitebark pine has been proposed by the US Fish and Wildlife Service for listing as Threatened under the Endangered Species Act. (I have blogged often about policy failures that have contributed to these introductions; today I am focused on agencies’ ability to respond.)
Funding agencies’ essential programs has fallen behind these calamities. APHIS funding has been steady or has risen slowly – at least not dropping – but not enough to deal with the growing threat.
Meanwhile, the key USFS programs have been cut by half or more. In 2010, USFS FHP and Research, together, allocated $32 million to efforts to understand and manage a dozen introduced pests: Asian longhorned beetle, emerald ash borer, sudden oak death, hemlock woolly adelgid, goldspotted oak borer, laurel wilt, thousand cankers disease, European gypsy moth, Port-Orford cedar root disease, Sirex woodwasp, and white pine blister rust (especially on whitebark pine). By 2021, this total had fallen to about $10 million. There was no indication that any USFS R&D funding has been allocated to recently detected, highly damaging pests, i.e., rapid ʻōhiʻa death, the polyphagous and Kuroshio shot hole borers, Mediterranean oak beetle, or beech leaf disease. USFS FHP has funded work on some of these pests through its “emerging pest” fund – but that fund is limited to $500,000 for the entire country.
At present, more than 228 tree species growing in the “lower 48” states are infested by an exotic pest. The 15 most damaging of the introduced species threaten 41.1% of the total live forest biomass in the 48 conterminous states. Additional trees on the Hawaiian and other Pacific islands are also being killed by non-native insects and pathogens. Non-native forest pests have caused a 5% increase in total mortality by tree volume nation-wide. The greatest increases in mortality rates have been a four-fold increase for redbay; and a three-fold increase each for ash, beech, and hemlock.
Introductions of tree-killing pests occur because we import things! The highly damaging wood-borers can arrive in crates, pallets, and other forms of packaging made of wood. Other pests – especially plant diseases – come here on imported plants. Gypsy moth and spotted lanternfly egg masses can be attached to virtually any hard surface, e.g., steel slabs, vehicles, stone, containers, or ship superstructures.
Imports from Asia pose a particularly high risk – illustrated by the Asian longhorned beetle, emerald ash borer, polyphagous and Kuroshio shot hole borers, sudden oak death, and spotted lanternfly.
U.S. imports from Asia rose almost a third between 2019 and 2020. No part of the country is safe. While nearly half of imports from Asia enter via Los Angeles/Long Beach, California, another 21% entered via New York – New Jersey and Savannah. Other ports in the “Top 10” were the Northwest Seaport Alliance of Seattle and Tacoma, Oakland, Norfolk, Houston, Charleston, Baltimore, and Mobile.
Pests don’t stay in the cities where they first arrive. Instead, they proliferate and spread to other vulnerable trees – often assisted by people moving firewood, plants or household goods. For example, less than 20 years after their first detections, the emerald ash borer has spread to 35 states, the redbay ambrosia beetle to 11.
[For more information, read my earlier blogs posted here or species-specific descriptions here.]
Please contact your Representative and Senators and urge them to push for increased funding for key programs managed by these two agencies. I describe funding needs below. I list members of the appropriate Congressional subcommittees at the end of this blog.
APHIS headquarters
USDA APHIS programs (all included under “Plant Protection and Quarantine”)
APHIS Program
FY 2020 (millions)
FY 2021 (millions)
FY 2022 ask
Tree & Wood Pest
$60.000
$60.456
$70 million
Specialty Crops
$192.000
$196.553
$200 million
Pest Detection
$27.446
$27.733
$30 million
Methods Development
$20.686
$20.844
$25 million
APHIS’ “Tree & Wood Pests” account has traditionally supported eradication and control efforts targeting only three insects: the Asian longhorned beetle (ALB), emerald ash borer (EAB), and gypsy moth. The program to eradicate the ALB has received about two-thirds of the funds — $40 million. There is encouraging progress in Massachusetts, New York, and Ohio. Clearly, this program must be maintained until final success is achieved. Plus the program must now counter the Charleston, South Carolina, outbreak, where more than 4,000 infested trees have been detected in an area of 58 square miles. (See my blog here, which describes the difficult conditions arising from wetlands in South Carolina.)
APHIS has terminated its emerald ash borer regulatory program, which had previously been funded at about $7 million per year. (See my blog). APHIS has said it will now focus on production and release of biocontrol agents, although it has not indicated the funding level. It is probable that EAB will now spread more rapidly to the mountain and Pacific Coast states, threatening both riparian woodlands and urban forests.
APHIS’ “Specialty Crops” program funds APHIS’ regulation of nursery operations to prevent spread of the sudden oak death pathogen. APHIS must improve that program to avoid a repetition of the 2019 incident, in which plants infected by the SOD pathogen were shipped to 14 states.
This budget line also supports efforts to manage the spotted lanternfly, which has spread from Pennsylvania to seven other mid-Atlantic states.
The “Pest Detection” budget line supports the collaborative state –federal program that detects newly introduced pests. Successful eradication and containment programs depend on early detection.
The “Methods Development” program assists APHIS in developing detection and eradication tools essential for an effective response to new pests.
USDA Forest Service
USFS PROGRAM
FY20
FY21
FY 22 ask
FHP Coop Lands
$32 M
$30.747M
$51 million (to cover both program work & personnel costs)
FHP Federal lands
$19 M
$15.485M
$25 million (ditto)
Research & Develop
$305 million
$258.7 million; of which about $3.6 million allocated to invasive species
$320 million; seek report language specifying $5 million for invasive species
The Mission of the USDA Forest Service is “To sustain the health, diversity, and productivity of the Nation’s forests and grasslands to meet the needs of present and future generations.” To achieve this mission, the Forest Service needs adequate funding to address the difficult challenge of containing the spread of introduced pests, protecting host tree species from mortality caused by those pests, and restoring decimated tree species to the forest. Meeting this challenge requires gaining scientific understanding of the pest’s and host’s biology and what motivates people to avoid activities that facilitate pests’ spread (e.g., transporting firewood that might harbor wood-boring insects).
Given the hundreds of damaging non-native pests, the Forest Service must set priorities. One attempt to do so is “Project CAPTURE” (Conservation Assessment and Prioritization of Forest Trees Under Risk of Extirpation). Priority species for forests on the continent are listed below. A separate study is under way for forests in Hawai`i, Puerto Rico, and U.S. Virgin Islands.
Florida torreya (Torreya taxifolia)
American chestnut (Castanea dentata)
Allegheny chinquapin (C. pumila)
Ozark chinquapin (C. pumila var. ozarkensis)
redbay (Persea borbonia)
Carolina ash (Fraxinus caroliniana)
pumpkin ash (F. profunda)
Carolina hemlock (Tsuga caroliniana)
Port-Orford cedar (Chamaecyparis lawsoniana)
tanoak (Notholithocarpus densiflorus)
butternut (Juglans cinerea)
eastern hemlock (Tsuga canadensis)
white ash (Fraxinus americana)
black ash (F. nigra)
green ash (F. pennsylvanica).
These 15 priority species should be the focus of both comprehensive gene conservation programs and tree breeding and restoration programs. Unfortunately, USFS programs do not reflect this recommendation.
Forest Health and Management Programs (FHM)
Despite severe cuts (see above), FHM has continued its commitment to projects addressing Port-Orford-cedar root disease, threats to whitebark pine, and thousand cankers disease; plus it is support for managing “lingering” ash which appear to survive EAB attack. However, I am concerned about past reductions in programs targetting laurel wilt and sudden oak death. And as I noted above, several highly-damaging pests lack a “program” at all. I applaud establishment of an “emerging pest” line. However, competition will be fierce for the $500,000 – pitting the invasive shot hole borers in California against the coconut rhinoceros beetle and rapid ‘ōhi‘a death in Hawai`i, against beech leaf disease in Ohio to Massachusetts.
And where is federal leadership on managing continued spread of the emerald ash borer, now that the USDA APHIS has terminated its regulatory program?
USDA Forest Service Forest and Rangeland Research Program
Effective programs to prevent, suppress, and eradicate non-native pests depend on understanding of the pest-host relationship gained through research. In recent years, about 1.5% of the USFS Research budget has been allocated to the non-native pests listed above. Past reductions have hit programs targetting hemlock woolly adelgid, white pine blister rust, sudden oak death, and the Sirex woodwasp. Programs targetting several other high-impact pests, including the Asian longhorned beetle, emerald ash borer, goldspotted oak borer, thousand cankers disease, and laurel wilt have been funded at a steady rate. I could find no documentation of USDA Forest Service research into beech leaf disease, rapid ʻōhiʻa death, or other pests currently killing trees.
Members of Key Congressional Committees
Note that some Representatives or Senators are members of subcommittees that fund both APHIS and the USFS. It is especially important that they hear from their constituents!
APHIS is funded through the Agriculture appropriations bill. Members of the House Subcommittee on Agriculture and Rural Development:
Sanford Bishop Jr., Chairman GA
Chellie Pingree ME
Mark Pocan WI
Lauren Underwood IL
Barbara Lee CA
Betty McCollum MN
Debbie Wasserman Schultz FL
Henry Cuellar TX
Grace Meng NY
Jeff Fortenberry, Ranking Member NE
Robert Aderholt AL
Andy Harris MD
David Valadao CA
John Moolenaar MI
Dan Newhouse WA
Members of the Senate Subcommittee on Agriculture and Rural Development:
Tammy Baldwin, Chair WI
John Merkley OR
Dianne Feinstein CA
Jon Tester MT
Patrick Leahy VT
Brian Schatz HI
Martin Heinrich NM
Ranking Republican John Hoeven ND
Mitch McConnell KY
Susan Collins ME
Roy Blunt MO
Jerry Moran KS
Cindy Hyde-Smith MS
Mike Braun IN
The USFS is funded through the Interior appropriations bill. Members of the House Subcommittee on Interior and Related Agencies: add states
Chellie Pingree, Chair ME
Betty McCollum MN
Derek Kilmer WA
Josh Harder CA
Susie Lee NV
Marcy Kaptur OH
Matt Cartwright PA
David Joyce, Ranking Member NC
Mike Simpson ID
Chris Stewart UT
Mark Amodei NV
Members of the Senate Subcommittee on Interior and Related Agencies:
Jeff Merkley, chair OR
Dianne Feinstein CA
Patrick Leahy VT
Jack Reed RI
Jon Tester MT
Chris van Hollen MD
Martin Heinrich NM
Ranking Rep. Lisa Murkowski AK
Roy Blunt MO
Mitch McConnell KY
Shelly Moore Capito WV
Cindy Hyde-Smith MS
Bill Hagerty TN
Marco Rubio FL
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
arrows indicate red maples in the swamps of ALB regulated site in South Carolina photo by David Coyle
The Asian longhorned beetle (ALB) is one of the most threatening of the hundreds of non-native insects and pathogens introduced to American forests since European colonization began 400 years ago. The ALB attacks about 100 species of trees in 12 or 13 genera; it prefers maples, poplars, willows, and elms. Forests with substantial components of susceptible species constitute 10% of forests on the U.S. mainland and nearly all of Canada’s hardwoods. Host trees species also make up a significant proportion of trees in urban areas. A two-decade old estimate is that ALB could cause more than $1.2 billion in damage to urban trees [Coyle et al. 2021; full citation at the end of the blog]. The contemporary estimate would be higher.
The ALB began showing up in imports and in warehouses less than a dozen years after the U.S. opened trade with China [see Chapter 3 of Fading Forests II; url provided at the end of this blog]. Now there is a new infestation in South Carolina that threatens to be the most difficult to eradicate. Given the level of resources and extended commitment this will demand from APHIS and South Carolina, I worry that the agencies and Congress will give up. To find more money, will the agency take funds from other pests that also need to be addressed? Will it seek – and receive – emergency funding? Congress is currently considering funding for APHIS for the fiscal year that begins in October. Let’s inform them of the need to ensure adequate resources to carry forward necessary eradication efforts.
ALB in the U.S.: 25 Years of Repeated Infestations and Eradications
The first established ALB population to be detected was that in Brooklyn, New York, in 1996. Since then, seven more outbreaks have been detected in the United States [Poland et al. 2021; South Carolina press release] plus two in Canada. Several populations have been eradicated: a single population in Illinois, several populations in New Jersey, three populations in New York; a small outlying population in Ohio (APHIS newsletter Feb 2021); and two Canadian outbreaks.
Despite the U.S. and Canada having adopted regulations requiring treatment of wood packaging from China effective January 1999, ALB larvae continue to be detected in wood packaging from that country. Between 2012 and 2017, the ALB was intercepted six times in wood packaging made of Populus wood – each time originating from a single wood-treatment facility in China (Krishnankutty et al. 2020 – full citation at the end of the blog).
Port of Charleston; photo by Walter Lagrenne, South Carolina Port Authority
ALB Near Charleston, S.C.: Recently Detected; Must be Eradicated
The most recent detection is near Charleston, South Carolina. As usual, a beetle was found by a member of the public. Dendrological studies indicate that this infestation was seven years old at the time of its detection in May 2020, meaning it began about 2013 (Coyle et al. 2021). As the authors note, it has proved impossible to determine whether the South Carolina outbreak resulted from transport of infested wood from the Ohio outbreak or from China directly. Lots of visitors travel from the Midwest to South Carolina every winter. The center of the primary area of infestation includes a railway and an RV park which might be utilized by such travelers. On the other hand, two ports that receive high volumes of incoming shipping containers including wood packaging are nearby — Charleston, SC and Savannah, GA (Coyle et al. 2021). Charleston imported almost 666,000 containers (measured as 20-foot equivalents, or TEUs) in 2013.
Even under the best circumstances, eradicating an ALB infestation is difficult. Eradicating the Chicago outbreak took ten years [Poland et al. 2021]; eradicating the Brooklyn infestation took 23 years [APHIS ALB newsletter]. Massachusetts might be on the verge of eradicating the Worcester outbreak twelve years after it was detected because only one infested tree was found in 2020 [Felicia Hubacz at Northeast Forest Pest Council meeting, March 2021]
Eradication entails removing large numbers of trees – more than 171,000 in the Northeast and Midwest; and pesticide treatment of at least 800,000 [Poland et al. 2021]. Tens of thousands of trees must be inspected – especially in areas with significant woodland areas like the South Carolina site. In Clermont County, Ohio, 3,500,000 trees have been surveyed in the regulated area – which is 56 square miles [APHIS newsletter]
In South Carolina, APHIS and the state are already regulating 72.6 mi2 — and that is before the full extent of the infestation has been delimited. This regulated area is larger than the Ohio and New York regulated areas, although smaller than that in Massachusetts (110 mi2 Coyle et al.). As of February 2021, 4,425 infested trees have been identified (APHIS newsletter]. Ninety-eight percent are red maples; half of the others are willows (Coyle et al.) In May 2021, APHIS expanded the quarantine zone to 76.4 square miles (APHIS press release May 21, 2021).
So APHIS and South Carolina face a great deal of hard work. But acreage and numbers of trees affected don’t convey the real extent of the challenge.
The first challenge is anticipating the timing of events in the ALB life cycle. Scientists understand a great deal about the ALB life cycle. However, that knowledge all applies to areas with temperate climates such as the U.S. northeast, southern Canada, and Europe. South Carolina has a subtropical climate. How will the warmer climate affect the beetle’s speed of development, timing of emergence, etc. Already, dendrologial studies indicate that the ALB in South Carolina might complete development from egg to mature adult much faster – in less than a year rather than one to four years (Coyle et al.)
working conditions in the South Carolina swamps; photo by David Coyle
An even bigger challenge will be trying to carry out searches for infested trees and standard responses. Removing infested trees and removing or applying pesticides to at-risk host trees is standard practice. Much of the regulated area has standing water and/or saturated soil. These conditions – plus the presence of venomous snakes and alligators – make visual surveys from the ground or by tree climbers difficult. Use of lifts and bucket trucks will be impossible. When infested trees are found, felling trees in swampy conditions presents a heighted risk for felling crews. And it will be impossible to operate the equipment needed to remove or chip infested trees (Coyle et al.). I believe it is impossible to use soil injection to treat at-risk trees under such conditions.
SOURCES
Coyle, D.R., R.T. Trotter, M.S. Bean, and S.E. Pfister. 2021. First Recorded Asian Longhorned Beetle (Coleoptera: Cerambycidae) Infestation in the Southern United States. Journal of Integrated Pest Management, (2021) 12(1): 10; 1–6
Krishnankutty, S., H. Nadel, A.M. Taylor, M.C. Wiemann, Y. Wu, S.W. Lingafelter, S.W. Myers, and A.M. Ray. 2020b. Identification of Tree Genera Used in the Construction of Solid Wood-Packaging Materials That Arrived at U.S. Ports Infested With Live Wood-Boring Insects. Commodity Treatment and Quarantine Entomology
Poland, T.M., T. Patel-Weynand, D.M. Finch, C.F. Miniat, D.C. Hayes, V.M. Lopez. 2021. Invasive Species in Forests and Rangelands of the United States. Springer.
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
map showing spread of beech scale, which facilitates beech bark disease
I recently participated in the 2021 annual meeting of the Northeast Forest Pest Council (virtual, of course). Speakers – most of them from state forestry agencies, but including students – presented a disturbing picture. Numerous established insects and diseases continue to spread. In some cases, they are resurging after weather-caused slow-downs. There are also a few bright spots.
The Alarming
To me the most alarming situation is that for American beech – because all three threats continue to expand.
Beech bark disease Since 2000, BBD has spread across southern Quebec into Ontario, Michigan, and Wisconsin; the Blue Ridge in Virginia; and central New Jersey.
Beech leaf disease Originally discovered near Cleveland in 2012, BLD has been spreading, primarily eastward.
BLD was detected for the first time in Massachusetts, in Plymouth and Bristol counties (on the coast North of Cape Cod). It might also be in Worcester. Both American and European beech trees of all sizes are affected; some of the largest are “on the verge” of death. (Felicia Hubacz)
The first detections in New Jersey are in Bergen and Essex counties – bordering southern New York. Both detections were by members of the public. Rosa Yoo says there is confusion about which state agency has the lead, so no official notices have been published (although the detection is recorded on the map). She hopes to establish long-term monitoring plots.
West Virginia now says that BLD is present in Tomlinson Run State Park in Hancock County. Kristen Carrington plans to focus detection efforts on the state’s norther panhandle which rises along the Pennsylvania border. She has established seven long-term monitoring plots.
Meanwhile, states where BLD was detected earlier continue to add new counties to the list of those infested. In New York, five new counties have been recorded. All the New York State finds have been on public lands, so the map doesn’t present the full picture (Carlson). In Connecticut, the disease is in all coastal counties and is more scattered in inland areas. Connecticut has set up some long-term monitoring plots. (Stafford)
New York is also trying to identify insect species associated with beech trees and beech litter – as a first step in trying to determine whether any vector the nematode that is thought to cause the disease. I suggest that it is also useful to understand which arthropod species might be at risk as beech decline. Don’t folks often lament the lack of this information for chestnut? Aren’t scientists praised for compiling initial lists for insects associated with ash?
Beech leaf mining weevil According to Jeff Ogden of the Nova Scotia Department of Lands and Forestry, this weevil has defoliated trees on 5987 hectares. First detected near Halifax in 2012, the weevil is now found throughout Nova Scotia. Some trees near Halifax have died. Ogden believes the weevil could be spread on movement of logs with bark and leaf litter. Camping is very popular in Nova Scotia, so the firewood risk appears real.
Also alarming is the resurgence of hemlock woolly adelgid across the region. HWA had been suppressed for a few years by harsh winters, but that reprieve is over. HWA is in 52 of 55 West Virginia counties (Kristen Carrington). Newly detected outbreaks are found across Pennsylvania and in the Adirondacks of New York. HWA continues to spread north – slowly – in New Hampshire and Vermont. In Nova Scotia, the outbreak detected in 2018 is spreading slowly to the West (Jeff Ogden).
All states are releasing a variety of biocontrol agents, often Laricobius nigrinus but also L. osakensis. Various agents have been released for decades — for example, Connecticut has released more than 125,000 agents over more than 20 years. I do hope the two Laricobius beetles prove to be more effective in controlling the agelgid.
Several states note that elongate hemlock scale (Fiorinia externa) is now at least as damaging as the adelgid.
Pennsylvania is growing hemlocks for restoration purposes; New Jersey has begun a similar program. See my earlier blog about efforts to breed hemlocks resistant to the adelgid, available here.
Spotted lanternfly is now established in nine states — from Ohio and West Virginia to Connecticut. It continues to spread. In the longer-established infestation areas of southeastern Pennsylvania, black walnut has been severely damaged by early instar larvae. In New Jersey, eight counties are under quarantine, but the insect has been detected much more broadly. The newest state is Connecticut, which found populations in several counties and is drafting quarantine regulations. Massachusetts, Maine, and Vermont have found some egg masses or evidence of infestation on goods entering from Pennsylvania, but not yet an established population.
The Not So Alarming — but Still Concerning
Asian Longhorned BeetleMassachusetts is consistently finding fewer trees infested by the ALB. In 2020, they found only one! It was isolated in the middle of a golf course. Intensive surveys and trapping in the vicinity found no other infested tree.
This is great news! However, I worry that resources will be withdrawn too soon – especially with APHIS’ need to fund an eradication program for the same pest in a swampy forest area in South Carolina where it will be difficult to work. Already Massachusetts reported that it has fewer traps and staff, and some difficulties accessing the lure.
Early Detection Efforts
New Jersey and West Virginia have carried out surveys of sassafras stands for the redbay ambrosia beetle (also here). West Virginia is also surveying for Phytophthora ramorum (the sudden oak death pathogen) and walnut twig beetle (vector of thousand cankers disease). Funding for surveys of the former probably came from USFS Forest Health Protection; for the latter, from APHIS. I applaud these “early detection” efforts.
Too Late for “Early Detection” but Getting Welcome the Attention
New Hampshire noted rising concern about Jumping worms. The state has received 48 complaints since 2017; 43 of these were in 2020. This led to a spirited discussion about invasive worms’ impacts. Don Eggen noted that concern focuses on soils in unglaciated regions. Non-native worms can destroy the duff layer. Most of the research has been carried out in the Midwest. See my earlier blogs about invasive earthworms here.
Tim Tomon reported that the USFS Morgantown WV research office has sampled the Allegheny NF. They have found other invasive earthworms but not jumping worms. Rosa Yoo of New Jersey alerted participants to the jumping worm research and management group – JWORM
Other Updates
Beech leaf disease
The USDA Forest Service has published a Pest Alert on BLD. Google it now. When a url becomes available I will update this notice. The flyer includes contact information for a site that provides both detection training and a place to record your finds.
Sudden Oak Death
The EU1 strain was detected in forest trees in Del Norte County, California in autumn 2020. This detection was both the first officially confirmed detection of P. ramorum in Del Norte County and the first detection of the EU1 strain in forest trees in California. The source is unclear. The nearest infestation is 12 miles away, along the Winchuk River in Curry County, OR; those trees are infected with the NA1 strain. The nearest known EU1 infestation is about 35 miles away. The site of the California EU1 infestation has minimal California bay laurel (Umbellularia californica). This detection has led to designation of Del Norte County as officially infested; it becomes the 16th California county so designated. [Information from the California Oak Mortality Task Force newsletter for December 2020, available here.]
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
Rep. Peter Welch of Vermont has reintroduced his bill to improve programs intended to prevent introduction of non-native forest pests and enhance efforts to reduce their impacts. The latter provisions include support for breeding trees resistant (or tolerant) to the pest. I hope H.R. 1389 will be adopted – then spur new efforts to conserve and restore forest trees! Please follow my suggestion below.
The Invasive Species Prevention and Forest Restoration Act H.R. 1389 is co-sponsored by Reps. Brian Fitzpatrick (PA), Annie Kuster & Chris Pappas (NH), and Elise Stefanik (NY).
“Invasive species are devastating to forests which are a central part of Vermont’s economy and our way of life. This bill will fund efforts to revitalize damaged forests and highlight the need for making this a priority within the federal government.”
Major provisions of H.R. 1389:
Expands USDA APHIS’ access to emergency funding to combat invasive species when existing federal funds are insufficient and broadens the range of actives that these funds can support.
Establishes a grant program to support institutions focused on researching methods to restore native tree species that have been severely damaged by invasive pests.
Authorizes funding to implement promising research findings on how to protect native tree species.
Mandates a study to identify actions needed to overcome the lack of centralization and prioritization of non-native insect and pathogen research and response within the federal government, and develop national strategies for saving tree species.
As I have described in earlier blogs, the measures adopted by federal and state governments to prevent non-native pathogen and insect pest introductions – and the funding to support this work – have been insufficient to meet the growing challenges. In just the past decade, several new tree-killing pests have been detected: polyphagous and Kuroshio shot hole borers, spotted lanternfly, two rapid ʻōhiʻa death pathogens, Mediterranean oak beetle, velvet longhorned beetle. Over the same period, the Asian longhorned beetle has been detected in Ohio and South Carolina; the emerald ash borer expanded its range from 14 to 35 states; the redbay ambrosia beetle and its associated fungus spread from five states to 11; a second strain of the sudden oak death fungus appeared in Oregon forests; and whitebark pine has been proposed by the US Fish and Wildlife Service for listing as Threatened under the Endangered Species Act.
During this same period, funding for the USDA Forest Service Forest Health Protection program has been cut by about 50%; funding for USFS Research projects targetting 10 high-profile non-native pests has been cut by about 70%.
One reason for this disconnect between need and resources is that the non-native tree pest problem is largely out of sight and therefore does not lend itself to the long-term public attention needed to remediate the threats. It is up to us to raise the political profile of these issues.
On the positive side, the passage of time has brought forth new solutions, a deeper understanding of the genetics of plants and animals, new measures for igniting public awareness and invasive identification, new technologies and strategies for helping trees adapt, and a recognition of what resources and organization it will take to mount a proper solution to the problem.
“Project CAPTURE” (Conservation Assessment and Prioritization of Forest Trees Under Risk of Extirpation) has proposed priority species for enhanced conservation efforts. Top priorities in the continental states are listed below. A separate study is under way for forests in Hawai`i, Puerto Rico, and U.S. Virgin Islands.
dead redbay on Jekyll Island, Georgia
Florida torreya (Torreya taxifolia)
American chestnut (Castanea dentata)
Allegheny chinquapin (C. pumila)
Ozark chinquapin (C. pumila var. ozarkensis)
redbay (Persea borbonia)
Carolina ash (Fraxinus caroliniana)
pumpkin ash (F. profunda)
Carolina hemlock (Tsuga caroliniana)
Port-Orford cedar (Chamaecyparis lawsoniana)
tanoak (Notholithocarpus densiflorus)
butternut (Juglans cinerea)
eastern hemlock (Tsuga canadensis)
white ash (Fraxinus americana)
black ash (F. nigra)
green ash (F. pennsylvanica).
For a brief explanation of Project CAPTURE, see my earlier blog here. For an in-depth description of the Project CAPTURE process and criteria for setting priorities, read Potter, K.M., M.E. Escanferla, R.M. Jetton, and G. Man. 2019. Important Insect and Disease Threats to United States Tree Species and Geographic Patterns of Their Potential Impacts. Forests 2019, 10. https://www.fs.usda.gov/treesearch/pubs/58290
Please ask your representative to co-sponsor H.R. 1389. Please ask your senators to sponsor a companion bill. For more information, contact Alex Piper at Alex.Piper@mail.house.gov or 202-306-6569 .
H.R. 1389 is endorsed by Vermont Woodlands Association, American Forest Foundation, Center for Invasive Species Prevention, the Reduce Risk from Invasive Species Coalition,, Entomological Society of America, and North American Invasive Species Management Association.
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
Horton House on Jekyll Island, Georgia – when the redbays were still alive! photo by Faith Campbell
A recent USFS book on invasive species reports that at least 58 species of bark and ambrosia beetles have been established in the US. Recent studies highlight very different situations due to two invasive ambrosia beetles. Here are summaries of each.
1. Laurel Wilt: Unmitigated Disaster in Atlantic and Gulf Coastal Plains – and Possibly More Widely
The disease laurel wilt, caused by the pathogen Raffaelea lauricola and vectored primarily by the redbay ambrosia beetle (Xyleborus glabratus) presents a dire contrast. (For this section, see Olatinwo, Fraedrich & Mayfield. 2021; full reference at end of the blog.) In the nearly 20 years since its first detection near Savannah, Georgia in 2002, laurel wilt has spread across more than 100 counties and parishes in 11 states from North Carolina south through Florida, west to eastern Texas, and as far northward as Kentucky.
Laurel wilt has killed hundreds of millions of trees in the plant family Lauraceae. Approximately 13 Lauraceae species in eight genera (depending on taxonomic proclivities!) are indigenous to the U.S. Individual species’ vulnerability appears to depend largely on size; the beetle is attracted to vertical stems of a certain diameter. As a result, the native tree species redbay (Persea borbonia), swampbay (Persea borbonia var. pubescens or P. palustris), and more recently sassafras (Sassafras albidum) have experienced the most damaging attacks. Also heavily attacked has been the commercial avocado (Persea americana) which is native to Central America.
sassafras photo by David Moynihan
While redbay is widespread in a defined geographic area – a long the Atlantic and Gulf Coastal Plain from North Carolina to Texas, sassafras is subcontinental: it is found in 28 states, 53 ecoregions, and 69 forest types. Approximately 80% of sassafras in affected areas have been killed. In recent years, spread has proceeded by many “jumps” to disjunct areas where sassafras occurs in isolation from other hosts. At present, approximately 52% of the range of sassafras might experience winter temperatures sufficiently cold to cause significant mortality of the redbay ambrosia beetle. However, this temperature protection is likely to decline to about10% of sassafras’ range as a result of even modest climate change (a 1.4 °C increase in winter minimum temperatures).
The ecological impact of loss of redbay and sassafrass are not clear. Both are sources of wildlife food. The principal specialist on redbay is the Palamedes swallowtail butterfly (Papilio palamedes), which is also the primary pollinator of a rare plant, yellow-fringed orchid. The rapid loss of swampbay on tree islands in the Everglades could facilitate establishment of even more individuals of the already widespread invasive plant species Brazilian pepper (Schinus terebinthifolius) or Melaleuca quinquenervia.
Other U.S. native plant species in the Lauracea family are apparently partially protected by the small diameter of their stems, which the beetle doesn’t find acceptable. These include – in the Southeast — the federally listed pondberry (Lindera melissifolia), “species of interest” pondspice (Litsea aestivalis), bog spicebush (Lindera subcoriacea), pepperleaf sweetwood (Licaria trianda), lancewood (Ocotea coriacea), and love-vine (Cassytha filiformis). The common shrub spicebush (Lindera benzoin) might be protected by its possession oflower quantities of the primary host volatile attractant. On the other hand, the widespread Pacific state shrub California laurel or Oregon myrtle (Umbellularia californica) is considered highly vulnerable, should laurel wilt be moved there in wood, mulch, or nursery plants.
Laurel wilt poses an unknown threat to the many plant species in the Lauraceae in Central and South America (750 species), Australia (125 species), Madagascar (135 species), and the Macaronesian Islands off the coasts of Europe and Africa – the Azores, Canary Islands, and Madeira. The commercial spice bay laurel (Laurus nobilis) is native to the Mediterranean region (and planted elsewhere, including in the US). However, its small size, discontinuous distribution and isolation from other lauraceous host species might prevent development of a widespread epidemic.
The authors note the absence of effective measures to manage laurel wilt 20 years after its detection. They recommend restricting long-distance movement of infested wood, associated public awareness efforts, development and deployment of resistant hosts, silviculture (sanitation), targeted application of preventive chemical treatments for protecting high-value trees, and severing root grafts in avocado orchards and sassafras clones. They note that success will be dependent on sustained funding and a commitment to long-term area-wide implementation.
[As I noted in past blogs about APHIS deregulating the emerald ash borer, it is now up to the states to regulate movement of firewood. The lead will continue to be the non-governmental “Don‘t Move Firewood” campaign. The message will continue to encourage the public to buy firewood where they burn it and to refrain from moving firewood from areas that are under Federal quarantine for other pests of firewood (e.g., Asian longhorned beetle). This campaign and the new National Plant Board guidelines stress that firewood is a high-risk pathway for many pests of national or regional concern; they do not focus on any particular species. Leigh Greenwood, director of Don’t Move Firewood, thinks this is a good approach.]
Mayfield adds that the spread northwards on sassafras means that state diagnostic pathology labs should familiarize themselves with protocols for isolating the laurel wilt pathogen.
As to developing resistant varieties of redbay, I note that Potter et al. 2019 ranked redbay as fifth species highest in priority for genetic conservation and restoration breeding efforts. However, it is my impression that few federal resources have been allocated to such an effort on behalf of redbay.
2. Ambrosia beetles in California
At least 22 of the recently-established ambrosia and bark beetles are in California. Heavily urbanized southern California appears to be particularly vulnerable to such introductions. The proximity of ship traffic and associated cargo, as well as the great diversity of potential hosts in the area’s urban forests, are likely to blame.
Two such pests are the polyphagous (PSHB) and Kuroshio (KSHB) shot hole borers [collectively, invasive shot hole borers (ISHB)]. John Boland has studied the KSHB outbreak in the Tijuana River estuary intensively since 2015. Two recent studies – 2019 and 2021– demonstrate the importance of ecological and tree-related factors in determining the severity of attack by this ambrosia beetle. See references at the end of the blog.
The most susceptible site is wet and nutrient enriched (in the case of the Tijuana River, due to pollution).
The most susceptible trees are young, fast growing, and have thin bark (allowing KSHB access) and wood of low density and high moisture content (providing ideal conditions for KSHB and associated fungi).
willows killed by KSHB in Tijuana River estuary; photo by John Boland
As Boland has noted, all of these conditions occurred in the “wet” forests close to perpetual streams in the Tijuana River delta in 2015. These factors led to dramatic levels of mortality, which have not been equaled in other southern California deltas. In the five years from 2015 to 2020, the beetle/fungus complex infested an estimate 350,000 willows and killed an estimated 123,000 in a boom-and-bust cycle. Since 2016, the trees in the Tijuana River estuary have regrown to almost pre-infestation dimensions. (Boland is not certain why these new, fast-growing trees have not been attacked by the KSHB that remain in the area. He suggests that a local pathogen, parasite, parasitoid or predator is keeping the KSHB in check – although this has not been verified.)
Willows near the main river channel (“Wet Forest” units) cumulatively had a fatality rate of 39%. Strikingly, more distant “Dry Forest” units had a combined fatality rate of only 9%.
The 2019 study linked the higher rates of infestation, damage, and mortality that occurred in trees near the main river channel to the presence of year-round water that was often enriched by a heavy load of sewage. The trees respond by growing rapidly, resulting in thinner bark and less dense wood. The KSHB attacked in much higher numbers, impeding water transport and weakening the trees’ structure so that they were more easily broken during windstorms.
The 2021 study provided further detail. By comparing bark samples cut from 27 infested trees at the height of the infestation, in 2016 – 17, Boland and Woodward demonstrated thicker bark on the “Dry Forest” trees protected the trees by limiting the density of KSHB entry points. The fewer holes reduced internal structural damage to the trees, which allowed them to survive. Boland notes that the protection might arise from either the bark thickness itself, or higher quantities of protective chemicals.
Repercussions
The results suggest that a KSHB individual actively searches for a suitable tree and then searches for the thinnest bark on that tree in which to drill its hole.
Trees can recover from KSHB attack, indicating that the fungal symbionts are only moderately pathogenic at worst.
The ISHB are likely to cause much less damage than indicated by the one early model developed before these factors were understood. We need new models for ISHB spread and impact that incorporate these factors of site characteristics and host tree condition.
Boland J.M. and D.L. Woodward. 2021. Thick bark can protect trees from a severe ambrosia beetle attack. PeerJ 9:e10755 https://peerj.com/articles/10755/
Olatinwo, R.O., S.W. Fraedrich & A.E. Mayfield III. 2021. Forests 2021, 12, 181. Laurel Wilt: Current and Potential Impacts and Possibilities for Prevention and Management
Potter, K.M., Escanferla, M.E., Jetton, R.M., Man, G., Crane, B.S. 2019. Prioritizing the conservation needs of US tree spp: Evaluating vulnerability to forest P&P threats, Global Ecology and Conservation (2019), doi: https://doi.org/10.1016/ j.gecco.2019.e00622.
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
Posted by Scott J. Cameron, former Acting Assistant Secretary for Policy Management and Budget , US Department of the Interior
locations in Hawaii Volcanoes National Park where ohia trees were infected by rapid ohia death pathogen in 2017
In 2019 Congress passed the John D. Dingell, Jr. Conservation, Management, and Recreation Act. Among other things, it directed the Department of the Interior to “develop a strategic plan that will achieve, to the maximum extent practicable, a substantive annual net reduction of invasive species population or infested acreage on land or water managed by the Secretary.” This provision triggered a year-long process of public involvement and inter-bureau coordination. The result was a plan published in January 2021. It represents the first attempt by Interior at a Department-wide multi-taxa, multi-year approach to invasive species. It has the potential to spur integration of invasive species work across the Department’s many bureaus and to focus each bureau’s efforts on a set of common goals, strategies, and performance metrics.
While Congress’ language is open-ended, any planning exercise is constrained by the most recent President’s budget and existing law. It is up to those of us who are not, or at least no longer, executive branch employees to advocate for plans unbound by those constraints.
In that spirit, I offer eight recommendations to improve invasive species management. Four are within existing authorities; four more are outside the current budgetary and statutory framework. Many more ideas are without a doubt worth pursuing.
Opuntia (prickly pear) cactus – common plant in western National parks and on Bureau of Land Management lands; under threat by cactus moth
First, within existing funding and legal authorities, the Department has unfinished business that it can act on now.
Secure approval of the package of categorical exclusions under the National Environmental Policy Act (NEPA) — now awaiting approval by the President’s Council on Environmental Quality (CEQ). Over many years agencies have documented how invasive species control improves, rather than harms, the environment. Absent an applicable NEPA categorical exclusion approved by CEQ, though, each such action needs to run the time- and money-consuming gauntlet of NEPA compliance. In the meantime, the invasive plants germinate, the invasive animals reproduce, and what might have been a localized and inexpensive problem has expanded geographically and in terms of cost and complexity. In the Fall of 2020 Interior submitted hundreds of pages of documentation on numerous practices proven to control invasive species without harming the environment. Due to time and staffing constraints at CEQ, these categorical exclusions still await action. Interior and CEQ should take prompt steps to finish them.
Allocate to the US Geological Survey at least $10 million of the roughly $90 million remaining available to the Secretary in CARES Act appropriations for research on invasive zoonotic diseases. These are diseases like COVID-19 and West Nile virus that can move from one species to another. Many zoonotic diseases fit the definition of invasive species, since they are not native to the United States and endanger human health. In the case of COVID-19 funding is available to the Secretary of the Interior, without need for further Congressional action, from funds appropriated by the CARES Act. The availability of these funds will expire at the end of September 2021, so Interior should provide this research funding to USGS as soon as possible.
Join the existing Memorandum of Understanding between the Western Governors Association (WGA) and the US Department of Agriculture’s Forest Service. These groups have established “a framework to allow the U.S. Forest Service (USFS) and WGA to work collaboratively to accomplish mutual goals, further common interests, and effectively respond to the increasing suite of challenges facing western landscapes.” This provides a forum to improve coordination between the States and the federal government on the management of invasive species, and Interior needs to be part of that team.
Interior should work with USDA to accelerate and intensify efforts to systematically improve coordination between the interagency Wildland Fire Leadership Council and the interagency National Invasive Species Council. Both Councils have member agencies that practice vegetation management using similar tools and techniques, although for different purposes. The two Councils should identify a select number of initiatives in FY21 where their efforts would benefit both wildland fire management and invasive plant management .
swamp bay trees in Everglades National Park killed by laurel wilt; photo by Tony Pernas
Four steps to implement the strategic plan outside the scope of current law and the President’s Fiscal Year 2021 budget. I offer the following:
Improve implementation of the Lacey Act program to list injurious species. There are both legislative and administrative elements to this proposal.
In a federal District Court decision on May 19, 2015, on a lawsuit filed by the Association of Reptile Keepers, the Court undid the longstanding Fish and Wildlife Service policy that the Lacey Act allowed FWS to ban interstate transport of injurious species. On April 7, 2017, the D.C. Circuit Court of Appeals upheld the District Court’s view. These rulings mean that FWS authority only applies to international commerce. Unfortunately, the court’s interpretation of the law and legislative history are reasonable, so Congress needs to amend the law to make it clear that FWS is explicitly authorized to regulate interstate commerce in injurious species. The Department of the Interior should work with the Department of Justice and the Office of Management and Budget to develop the necessary bill language and submit it to Congress.
At the same time, the FWS injurious species listing process is notoriously slow, even causing Congress to occasionally list species legislatively. The fact that these legislative initiatives have sometimes been promoted by Members of Congress who normally are opposed to more federal regulation signals just how awkward the current FWS process is. Thus there might well be strong bipartisan support to amend the Lacey Act on the interstate commerce matter. Acting on its own authority, FWS should procure an independent third party review of the injurious species listing process and ask the contractor to make suggestions for “business process reengineering” to improve and streamline current practices, along with evaluating whether higher funding or new technology is needed.
The Bureau of Reclamation, Department of the Interior, and the Office of Management and Budget should develop legislative language to submit to Congress for the 2022 Water Resources Development Act, that explicitly authorizes an aquatic nuisance species program in the Bureau of Reclamation. It could parallel the relatively new authority enjoyed by the Army Corps of Engineers and mandate increased coordination between the two water agencies.
Any climate change legislation pursued by Congress and the Administration should include provisions for addressing invasive species. Climate change will make some North American habitats more suitable for foreign organisms, as cold-intolerant species might be able to survive in more northern latitudes in the U.S. than previously was the case. Second, the disruptive effect of climate change on North American ecosystem structure and trophic relationships at any latitude will make those ecosystems more vulnerable to invasion. Finally, the spread of invasive species may in and of itself exacerbate climate change, such as through the increased carbon dioxide emissions from rangeland wildfires aggravated by the dominance of invasive cheatgrass.
The Senate Committee on Environment and Public Works and the House Natural Resources Committee should each hold oversight hearings on how best to help state and local governments detect and respond to new invasive species that are not within the statutory purview of USDA/APHIS. This is a complex topic, important for both ecological and financial reasons. Over the years several attempts to address it have failed. A thoughtful review by Congress and the Administration, which perhaps would lead to passage of new statutory authority and funding, is worth exploring.
The Author:
Scott Cameron recently left the federal government, where he had served as Acting Assistant Secretary for Policy, Management and Budget at the U.S. Department of the Interior. In that capacity he oversaw Department-wide budget, invasive species, natural resource damage assessment and restoration, environmental compliance and numerous administrative functions of this $14 billion agency with 65,000 employees. Previously, Scott held other civil service job (e.g., at the White House Office of Management and Budget) & political appointments in the federal government, on the staff of the Governor of California, and on Congressional staffs. While not in government, Scott led formation of the Reduce Risk from Invasive Species Coalition.
CISP welcomes 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.
Further information on the plant pests mentioned in the photo captions can be obtained at www.dontmovefirewood.org; click the “invasive species” button.
Japanese stiltgrass in Shenandoah National Park; photo by Jake Hughes, NPS
The recent appearance of a study by National Park Service (NPS) scientists quantifying the threat posed by invasive plants prompted me to seek updates on this issue. In May 2018, I blogged about NPS’ Invasive Plant Program Strategic Plan, which was issued in 2016. At the time, I got the impression that the program was struggling to gain support from NPS leadership in Washington, as well as leaders of individual parks. Has the situation improved since then?
The recent study, by Kathryn Miller and colleagues, focuses on National parks in the East, from Virginia to Maine. (I provide a full reference at the end of this blog.) I look forward to a planned follow-up article that will try to clarify drivers of invasion.
The Miller study appears to have been undertaken to partially fulfill one of the goals of the NPS’ 2016 Invasive Plant Program Strategic Plan. One of the actions under Goal 1 in the Plan was to quantify the invasive plant threat, the effort needed to manage it, and then to communicate the gap between needs and available resources. Miller et al. have quantified the threat to National parks in one region (not the entire country). However, they have communicated the gap between effort and need in only the most general way.
Protecting the forests in eastern National parks is valuable from many perspectives. The forests in these parks are older and have higher stand-level tree diversity than surrounding unprotected forests. Protecting their long-term condition also corresponds to the National Park Service’s (NPS) stated mission, as established in its Organic Act.
The study relied on National Park Service Inventory and Monitoring Program data from 1,479 permanent forest plots covering 39 eastern NP units located from Virginia to Maine. The data were collected over 12 years, in three survey cycles (2007–2010, 2011–2014, and 2015–2018).
The authors note that in forest ecosystems, invasive plants can reduce native diversity, alter forest structure, suppress tree regeneration, alter nutrient cycling, and modify disturbance regimes. Some – the shrubs and vines – also threaten human health by promoting increases in tick populations and associated Lyme disease risks.
Unsurprisingly, the data showed invasive plants to be widespread, and increasing. In 80% of the park units, there was a significant increase in at least one trend measuring abundance. Any decrease in plant invaders tended to be in herbaceous or graminoid species; that decrease was often counterbalanced by an approximately equivalent increase in invasive shrubs or vines. In 35 of the park units, more than half of the plots had at least one invasive plant species when the 2015-2018 survey began. In 10 parks (a quarter of those surveyed), every plot had at least one.
The most widespread species is Japanese stiltgrass (Microstegium vimineum). It is present in more than 75% of all park units and 30% of all 1,400 plots. This dominance is true despite the fact that stiltgrass does not extend north of Roosevelt-Vanderbilt National Historic Site in New York state (41o N latitude). Stiltgrass is also the most aggressive invader.
The second most widespread invaders are a group of shrubs and vines, including most notably Japanese barberry (Berberis thunbergii), Japanese honeysuckle (Lonicera japonica), multiflora rose (Rosa multiflora), and wineberry (Rubus phoenicolasius). I note – although the articles does not – that several of these have been deliberately planted – either to “enhance” ecosystems (multiflora rose) or as ornamentals (barberry). [Lehan et al. 2013 (full reference at end of blog) found that 95% of 125 shrub species introduced to the U.S. were introduced deliberately.] I know of no examples of deliberate planting of Japanese stiltgrass.
The most frequently detected non-grass herbaceous species is garlic mustard (Alliaria petiolata), which was detected in 20% of plots. Garlic mustard is found throughout the study area (Virginia to Maine). Tree-of-heaven (Ailanthus altissima) is the most common invasive tree. It is found in only 9% of plots and does not grow north of Roosevelt-Vanderbilt NHS. Again, both were intentionally introduced – and not noted as such in the article.
Because they could not identify the source populations for each plot, the study could not directly measure rates of establishment and expansion. The data did allow tracking rough trends in each park.
Parks with the highest abundance tended to be near densely populated areas. However, this pattern was not universal. For example, Prince William Forest Park in the outer Virginia suburbs of the District of Columbia metro area was one of two of the least invaded park units.
Prince William Forest Park
(note the prevalence of beech – I fear for the arrival of beech leaf disease!)
Total invasives increased significantly in 21 of the 39 parks for at least one metric. In 10 parks (a quarter of all parks), total invasives increased significantly in two of the three metrics. Antietam National Battlefield experienced the steepest increases.
The authors note that invasive plants continue to establish and expand, even in already heavily invaded forests. Thus they found little evidence of saturation. This finding conflicts with invasion theory. They also found antagonistic interactions between invasive species to be common.
The authors said managers should prioritize efforts to control Japanese stiltgrass and the shrubs and vinesdue to their widespread occurrence, rapid expansion, ability to suppress tree regeneration and understory diversity, and – in the case of the shrubs and vines, link to ticks.
The authors noted the need to better understand the drivers and impacts of invasive plants in eastern forests. They mentioned the overabundance of white-tailed deer (Odocoileus virginianus), latitude, climate change, fragmentation and urbanization. I have urged them to include analysis of deliberate planting of various species on lands within the park units or nearby. They have said that they will do so in the planned follow-up article.
The authors propose that deferred management of natural resources receive attention and sustained commitment on par with the attention to deferred maintenance of the park units’ infrastructure. The maintenance backlog has been addressed through recent legislation: the Great America Outdoors Act which provided $6.5 billion over five years to address deferred maintenance projects in all 419 national park units. I believe that these projects will not address invasive species, which are managed under the “Natural Resources” budget account, not “Maintenance”. Some “Maintenance” projects probably will include control of invasive plants. A former Interior Department official has suggested that resource management activities might be funded under another section of the legislation, which provides $900 million under the Land and Water Conservation program. I hope this is true.
National Park Service’ Overall Invasive Plant Program Now
In response to the mandate in the John D. Dingell, Jr. Conservation, Management, and Recreation Act (Public Law 116-9), the Department of Interior has issued a department-wide invasive species strategy. Will issuance of the new strategy provide impetus to the NPS to seek funding to implement its 2016 invasive plant strategic plan? Will Congress provide funds for this purpose?
Finding out the current status of National Park Service took a little effort. The NPS’ website has “popular” information about the efforts of individual regional Invasive Plant Management Teams (see links at the end of this blog). These posts provide only the briefest overview of program achievements and do not compare those accomplishments to the goals in the 2016 plan.
However, Terri Hogan, Invasive Plant Program Manager in the Biological Resources Division, provided following information:
NPS leadership now supports the agency’s invasive plant effort. The national Invasive Plant Program (IPP) contributes to the annual Natural Resource Stewardship and Science Directorate (NRSS)’ Biological Resource Division (BRD) work plan. All is guided by the “Four Pillars to Guide Natural Resource Activities and Investments”, adopted in 2016.
It is not clear that invasive species have the highest priority under this regime. The four “pillars” are
Holding the line – includes conserving biodiversity by removing invasive plants
Managing amid Continuous Change – includes conducting risk assessment and taking other actions to contain future exotic species
Leveraging for Conservation at Scale
Enhancing Stewardship and Science Access and Engagement
Cooperation with owners of neighboring private lands has been enhanced by engagement of the Western Governors Association and state and local political leaders. Many parks participate in Partnerships for Invasive Species Management (PRISMs), CISMS, and Cooperative Weed Management areas (CWMAs). This collaboration has been strengthened by adoption of the John D. Dingell, Jr. Act (see above).
In practice, the focus appears to still be on the Invasive Plant Management Teams (IPMTs). There are now 17 teams. Fifteen are funded through the national office. One is funded by an individual park; one funded through a regional office. Annual reports have been published for FYs 2017 and 2018. The FY19 report has been held up but should be posted soon.
The reports provide brief description of the overall program and vignettes of particular activities. There are more detailed – but still anecdotal – reports for each of the teams. It is difficult to determine whether there has been overall progress. For example, the reported total infested acreage increased from 133,658 acres in FY17 to 301,195 acres in FY18. This presumably reflects more intense monitoring as well as a probable increase in real infections. (The infested acreage figures do not address intensity of invasion on these acres.) The teams cumulatively treated 8,937 acres in FY 2017; 8,331 acres in FY 2018. They carried out inventory and monitoring projects on 169,057 acres in FY17, 210,000 acres in FY18.
Since the Miller article concerns the region from Virginia to Maine, I checked the FY17 and FY 18 reports from the Invasive Plant Management Teams from the Mid-Atlantic, National Capital Area, and Northeastern regions. The Mid-Atlantic team emphasized work on wavyleaf basketgrass and meadows in parks established to protect cultural or historic sites. The National Capital Area team emphasized partnerships and success eradicating Giant Hogweed (Heracleum mantegazzianum) on private land neighboring Rock Creek Park. The Northeastern Team serves 25 parks; the report emphasized leveraging resources and testing efficacy of pre-emergent herbicide for control of Japanese stiltgrass. With this exception, the teams do not appear to be prioritizing the species recommended for action by the Miller study.
Brief, “popular” articles about the NPS’ invasive plant effort are available here
Lehan, N.E., J.R. Murphy, L.P. Thornburn, and B.A. Bradley. 2013. Accidental Introductions are an Important Source of Invasive Plants in the Continental United States. American Journal of Botany 100(7): 1287–1293. 2013.
Miller, K. M., B. J. McGill, A. S. Weed, C. E. Seirup, J. A. Comiskey, E. R. Matthews, S. Perles, & J. Paul Schmit. 2020. Long-term trends indicate that invasive plants are pervasive and increasing in eastern national parks. Ecology. 00(00):e02239. 10.1002/eap.2239
Posted by Faith Campbell
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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
