biological control – Center for Invasive Species Prevention

What I learned at the NPB meeting

The National Plant Board’s members are the lead plant health officials of the states and territories. Many federal officials also attend – from APHIS and DHS Bureau of Customs and Border Protection. Representatives of other North American phytosanitary entities participate – i.e., Canada, Mexico, and the North American Plant Protection Organization (NAPPO). Some stakeholder groups participate, especially the nursery industry. I have attended these meetings for over a decade because they provide an overview of pest issues and programs plus an unparalleled opportunity to network. The Nature Conservancy’s Leigh Greenwood also attends. We are the only representatives of the species conservation community to attend – others are missing great opportunities.

Here, I’ve listed 10 items that are among the most important the group discussed.

1) The funding situation for APHIS is worse than I realized

APHIS Administrator Mike Watson and Deputy Administrator (for plants) Mark Davidson both spoke about the need to cut programs to stay within the limits set by congressional appropriations. Funding for APHIS, as a whole, was cut only 1% for the current year (Fiscal Year 2024), cost-of-living salary increases mean less money for programs. (I believe Dr. Watson said $41 million less for FY24). If FY25 funding is the same, Congressionally mandated additional payraises will mean an another $20 million decrease in program funding.

Dr. Davidson said that the plant programs (Plant Protection and Quarantine) had been cut by 5% in FY24. However, Congress did not finalize the funding levels until about half-way through the fiscal year – so staying within the limits required even more severe cuts to programs in the remainder of FY24. To stay within these limits, APHIS cut several programs, among them a $3.6 million cut from the “tree and wood pest” program. This meant loss of funds to manage the polyphagous and Kuroshio shot hole borers, smaller cuts for programs managing Asian longhorned beetle and emerald ash borer, and perhaps the Asian flighted spongy moth. They anticipate additional cuts in these programs in FY25. The one bright light is the Section 7721 Plant Pest & Disease Management & Disaster Prevention Program. It provides steady funding for a range of plant health programs. The House version of the still-pending Farm Bill calls for increasing funding for this program by $15 million each year.

Nearly 100% ash trees in Oregon wetland — exposed to spreading EAB. Photo by Wyatt Williams, Oregon Department of Forestry

Remember this when I ask you to lobby for appropriations! If we don’t advocate for funding the programs dealing with “our” pests, they will shrink.

Watkins and Davidson also worry that whoever is the next secretary of USDA might not support the agency when it seeks to withdraw funds to cover emergencies from the Commodity Credit Corporation – as Secretary Vilsack has.

APHIS and the DHS Customs and Border Protection (CBP) both praised a recent regulatory action that increases user fees for importers having goods cleared at ports. Kevin Harriger, CPB official in charge of agriculture programs, said the new funds would allow CBP to hire 700 new agricultural inspectors (currently there are 2,800 agricultural officials). That sounds great, but … when trade and passenger volumes crashed early in the COVID pandemic, things looked dicey for a while. Plus – as I have argued repeatedly – real protection against pest introductions will come from stronger policies, not ramped-up inspections.

Pathologist Bruce Moltzan reported on the USFS Forest Health Protection program. He pointed out that the USFS has a very limited toolbox. In this fiscal year, the program has about $48 million, after salaries, to support its activities. Projects targetting insects receive 70% of the funding; those targetting pathogens 15%.

2) Invasive hornets

Washington State has not found any new nests of the Northern (formerly Asian) giant hornet (Vespa mandarinia). Miraculous!

However, Georgia detected another species, the yellow-legged hornet (Vespa velutina), near Savannah in August 2023. The Georgia Department of Agriculture, APHIS, and the University of Georgia are working to find nests – which are located at the top of tall pine trees in residential areas. Five nests were found in 2023; another four so far in 2024. Georgia hopes to place traps 100 miles out from each detection site. Like the northern hornet, V. velutina preys on honey bees. It was probably transported by ship or with its cargo.

A third species, V. tropica, has been introduced on Guam.

3) Better Federal-State Cooperation — Sometimes

APHIS and the state phytosanitary officials have set up structures – e.g., Strategic Alliance/Strategic Initiative, or SASI – to work together more closely. CBP joins the coordinating meetings. One program described at the meeting is the effort to contain spread of the box tree moth (Cydalima perspectalis). This effort came out of discussions at last year’s Plant Board meeting, with follow-up gatherings of APHIS, the states, and the nursery industry. The moth is known to be present in New York, Massachusetts, Michigan, Ohio, and now Delaware – plus several Canadian provinces.

A second project concerns how much data to share about state detections of pests – which are recorded in the National Plant diagnostic Network database. These data have accrued over 20 years … and are sought by both other states and academic researchers. States are often reluctant to allow public review of detection data because they fear it will cause other states or private parties to avoid buying plants or other goods from the infested area. While the project team has not yet decided how to deal with these conflicts, they said they were more inclined to share “nonconsequential data” – meaning data on a pest everyone already knows is present, not a pest under regulation or a new detection. In other words, “consequential” seems to pertain to industry profits, not damage to agricultural or natural resources.

EAB-killed ash along Mattawoman Creek, Maryland. Photo by Leslie A. Brice

4) Update: 20 years of tackling the emerald ash borer

Craig Kellogg, APHIS’ chief plant health representative in Michigan, reviewed 20 years of dealing with the emerald ash borer (EAB). He is optimistic about the impact of the biocontrol agents that have now been released in 32 states and four provinces. The larval parasitoids are dispersing and EAB densities are coming down. He conceded that over-story and mature ash are still dying, but says ash in long-infested areas are regenerating well. Scientists agree (see Wilson et al. 2024; full citation at end of the blog). Woodpeckers are still the most effective biocontrol agent of EAB for over-story ash, especially in locations where introduced parasitoids are not established. So far, the growing numbers of biocontrol agents are still parasitizing too few EAB larvae to prevent decline of over-story ash trees.

5) Flighted Spongy Moths

APHIS reported on recent detections of flighted spongy moth from Asia on ships coming to U.S. ports. The program covers four closely related species of Lymantria. All have much broader host ranges than Lymantria dispar, plus the females are capable of sustained flight, so they spread more rapidly.

The principal strategy to prevent their introduction is to require ships that call at ports along the Pacific coast in Russia, China, Japan, and North and South Korea to ensure that the ships’ superstructures and cargo are clean. Before arriving at U.S. ports, the ship’s captain must inform CBP where it has called over the last 24 months. Then, CBP conducts an inspection. If CBP inspectors find a small number of egg masses, they remove the eggs and spray pesticide. If the inspectors detect a large number of egg masses, the ship is ordered to leave port, clean itself, and undergo re-inspection before it can return.

Four countries in the Americas – the U.S., Canada, Chile, and Argentina – and also New Zealand have very similar programs.

Detections follow natural changes in population levels in the exporting regions. APHIS’ program leader, Ingrid Asmundsson, reported on an unfortunate coincidence in 2014. A huge moth population outbreak occurred simultaneously with very low fuel prices in Russia. The latter attracted many ships to call there. An even bigger population surge occurred in 2019. Asmundsson expects another high-moth period this year.

flighted spongy moths infesting a ship superstructure

APHIS is working on putting this program on a regulatory foundation; this would allow the agency to be more specific in its requirements and to impose penalties (other than expulsions from ports). I’ll let you know when the proposed rule is published for comment.

6) Regional Reports: Old Pests, New Pests

Representatives of the regional plant boards informed us of their “new pest” or other concerns.

Gary Fish, president of the Eastern Plant Board, mentioned

the need for additional research on management of beech leaf disease
concern about impact of box tree moth and vascular streak dieback on the nursery industry (the latter is a threat to dogwood and redbud)
spread of elm zig-zag sawfly in Vermont and Connecticut
awareness that laurel wilt is moving into Virginia and maybe farther north.

elm zig-zag sawfly; photo by Gyorgy Csoka *via* Bugwood

There was a more general discussion of beech leaf disease. What can be done, given that the disease is so widespread that no one is regulating movement of beech. Gary Fish advised outreach and efforts to reach agreement on management approaches. Chris Benemann, of Oregon, suggested informing other states so that they can decide whether to take regulatory action. A representative of CBP urged engaging stakeholders by asking for their help.

Chris Benemann, President of the Western Plant Board, expressed concern about APHIS’ reduced funding for spongy moth detection and control efforts. She also worries about the recently detected population of Phytophthora austrocedrii in an Oregon nursery. The western states are also focused on several longstanding pest problems – grasshoppers, Japanese beetle; and a new beetle from Australia that is attacking almonds, pistachios, and walnuts.

tree infested by hemlock woolly adelgid; photo by F.T. Campbell

Megan Abraham of Indiana reported that members of the Central Plant Board are concerned about

funding decrease for APHIS and USFS efforts to slow the spread of spongy moth and manage Asian longhorned beetle and emerald ash borer;
Invaders associated with Christmas decorations, e.g., hemlock woolly adelgid, elongate hemlock scale, and balsam woolly adelgid
spotted lanternfly finding new ways to travel;
invasion by beech leaf disease and possibly by sudden oak death;
elm zig-zag sawfly entering the region;
boxwood blight, potato pests, honeybee pests, and invasive plants – e.g., Hydrilla.

She noted that nursery stock is increasingly coming from more distant – and cheaper – producers, raising the risk of new pests being introduced.

Finally, Abraham expressed concern about decreased funding at the same time as the need is growing – and asked with whom states should collaborate in order to reverse this trend.

Kenny Naylor of Oklahoma, Vice President of the Southern Plant Board, concurred that funding levels are a major concern. He mentioned specifically the spongy moth Slow the Spread program and eradication of the Asian longhorned beetle outbreak in South Carolina. Another concern is the Georgia hornet outbreak.

7) Phasing Out Post-Entry Quarantine

APHIS and the NPB have agreed to phase out the post-entry quarantine (PEQ) program. A program review revealed several problems, some of which astound me. When examining plants in quarantine the scientists still relying on visual inspection! And they are looking for pests identified 45 years ago (1980)! While I think PEQ programs can be valuable in preventing introduction of disease agents, as implemented in recent decades it does not. Twenty years ago, citrus longhorned beetles escaped from a “quarantine” area in a commercial nursery in Washington state. These Cerambycids are more than an inch long!

citrus longhorned beetle; photo by Art Wagner, USDA *via* Bugwood

Part of this phase-out is to transfer plant species harboring pests of concern to the Not Authorized for Importation Pending Pest Risk Assessment (NAPPRA). While the APHIS speaker said that NAPPRA allows the agency to act quickly when it detects evidence of pest risk, I have found lengthy delays. The third round of proposals was published in December 2019! The fourth round of species proposed for NAPPRA listing should be published soon; a fifth round is now in draft inside the agency.

8) Christmas Greens – Spreading Pests

Officials from Oregon, Maine, and Illinois described their concerns about pests being spread by shipments of various forest or plant products, especially Christmas greens. Mentioned were spongy moths, link hemlock woolly adelgid, link elongate hemlock scale, balsam woolly adelgid, link and box wood moth. Part of the challenge is that the vectoring items are often sold by unregulated outlets – multiple stores, Christmas tree lots – and through on-line or catalog outlets. There are also extreme demands on the regulatory enforcement staff during the brief holiday sales season. Several states are unsure whether they have authority over decorative products – although others pointed out that they are regulating the pest, regardless of the object for sale or type of store.

9) Pests in Firewood

Leigh Greenwood of The Nature Conservancy noted that the state agencies that issue firewood regulations – often the plant protection organization (state department of agriculture) — do a good job alerting the public about the risks and rules. However, the public looks first to state parks agencies for information about camping – and those agencies have less robust educational efforts. It is important to put the message where the public can find it when they don’t know it exists – before they include firewood from home in their camping gear.

10) Projects of the North American Plant Protection Organization

The North American Plant Protection Organization (NAPPO) is working on several projects of interest to those of us concerned about tree-killing pests. One project is evaluating risks associated with wood products, especially how well one international regulation, ISPM#15 is working for dunnage. Another projects is testing the efficacy of the heat treatment specified by ISPM#15 (50^o C for 30 minutes). A third project — almost completed – is evaluating fumigants that can be alternatives to methyl bromide.

In conclusion, each annual meeting of the National Plant Board is packed with new information, updates on current pests, and comments on by the state agencies who suggest new approached to APHIS and hold the agency to account. It is well worth attending. Information about upcoming meetings of both the national and four regional plant boards is posted on the NPB website, https://www.nationalplantboard.org/

Signatories to the APHIS-NPB strategic alliance

SOURCE

Wilson, C.J., T.R. Petrice, T.M. Poland, and D.G. McCullough. 2024. Tree species richness and ash density have variable effects on emerald ash borer biological control by woodpeckers & parasitoid wasps in post-invasion white ash stands. Environmental Entomology.

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 https://treeimprovement.tennessee.edu/

www.fadingforests.org

APHIS Annual Report Describes Helpful Programs … Since Cut Back Because of Funding Shortfalls

Flighted spongy moths infesting a ship’s superstructure

USDA’s Animal and Plant Health Inspection Service (APHIS) has issued its annual report for Fiscal Year 2023. The report is part of an enhanced outreach effort that I believe is an effort to persuade the Congress to provide additional funds. However, as I describe below, at this summer’s annual meeting of the National Plant Board, link APHIS’ leadership stated that funding shortfalls are forcing them to curtail many programs. These include ones important to those of us concerned about threats to North American trees. I applaud this action and hope it succeeds!

The report contains some good news but I consider the overall approach depressing. Tree-killing pests continue to receive little attention. The report also emphasizes APHIS’ efforts to facilitate export of agricultural products – an understandable stance given American politics.

The opening summarizes the agency’s activities includes:

Examples of programs targetting pests abroad, before they can reach the U.S. All are fresh fruits and vegetables;
APHIS or staff at U.S. borders:
- Approved (cleared) 27,235 shipmentscontaining over 1.87 billion plant units (e.g., a single plant or cutting, or vial of tissue culture plantlets) and 670,811 kilograms of seeds. They intercepted 2,176 quarantine pests. (APHIS carry out these inspections at Plant Inspection Stations – separate from the port environment where DHS Customs and Border Protection (CBP) staff inspects other cargo.)

Identified approximately 92,000 pestsfound during CBP inspections of cargo, mail, and express carrier shipments and took quick action to prevent those of concern from entering the U.S.
Facilitated entry of regulated agricultural cargo by monitoring more than 62,000 treatments of various kinds, that is, fumigations, cold or heat treatments, and irradiation.
Examples of APHIS’ efforts to slow pests’ spread within the country cited plant pest surveys — with coordinated responses — for approximately 45 pests. Also APHIS described funding to help citrus growers combat citrus greening.
The report has separate subreports on the following programs: risk analysis, pest detection, “specialty crop” pests, and tree and wood pests. The last two contain information specific to our interests.

Tree and Wood Pests

This program protects forests, private working lands, and natural resources. It targets specific pests: the Asian longhorned beetle, emerald ash borer, spongy moth, and most recently the invasive shot hole borers. The report notes that numerous native, widespread hardwood tree species are vulnerable to these pests. APHIS asserts an economic justification for the program: conserving forests enhances rural communities’ economic vitality, supports forest-related industries, and maintains the ecosystem services provided by urban trees.

Unfortunately, at this summer’s annual meeting of the National Plant Board APHIS leadership said funding shortfalls forced them to pull back on all these programs.

Programs as Described in the Report

Asian Longhorned Beetle

ALB eradication aims to protect the 30% of U.S. trees that are ALB hosts. These trees support multi-billion-dollar maple syrup, timber, tree nursery, trade, and tourism industries. After reviewing the history of ALB detections, starting in Brooklyn in August 1996, the report describes APHIS’ eradication strategy as comprising surveys, regulatory inspections and quarantine restrictions, removal of infested and high-risk trees, and chemical treatment applications. In FY 2023, the program surveyed more than 763,000 trees across the four regulated areas: New York, Massachusetts, Ohio, and South Carolina. Each program is summarized.

Good news at two locations. On Long Island: only 11 new infested trees were found after a survey of 43,480 trees. In Worcester County, Massachusetts, no new infested trees were found after surveying nearly 360,000 trees. However, in Tate Township, Ohio, surveys detected 163 new infested trees. And in

South Carolina, the program is at an earlier stage — surveying a portion of the quarantine area. The program surveyed nearly 140,000 trees and removed 1,700 in FY 2023.

At the National Plant Board Meeting, Deputy Administrator Mark Davidson explained that the FY2024 appropriation cut $3.6 million from the “tree and wood pests” account. This required the agency to reduce funding for the ALB eradication program.

Emerald Ash Borer

The report summarizes the spread of EAB since its first detection in 2002 in Michigan to 37 states and the District of Columbia (APHIS does not mention EAB’s presence in five Canadian provinces.)

Saying that EAB has spread beyond what a regulatory program can control, the report notes that APHIS ended the regulatory program in FY 2021. In FY 2023 the agency continued the transition to a program relying primarily on biocontrol. In FY2023, APHIS provided parasitoids to 155 release sites – three in Canada, the rest in 122 counties in 25 states. APHIS and cooperators continue to assess their impacts on EAB populations and tree health at release sites and nearby areas. Field evaluations indicate the EAB parasitoid wasps and other EAB natural enemies (woodpeckers) are protecting regenerating sapling ash from EAB.

Spongy Moths

Spongy moths (the species formerly called European gypsy moths) are established in all or parts of 20 eastern and midwestern states, plus the District of Columbia. APHIS and state cooperators regulate activities in the quarantine area to prevent the moths’ human-assisted spread to non-quarantine (non-infested) areas – primarily West coast states. To address the moths’ natural spread, APHIS PPQ monitors the 1,200-mile-long border of the quarantine area and adds newly infested areas to the regulated area. The USDA Forest Service – APHIS – Slow-the-Spread Foundation program has greatly reduced the moth’s rate of spread and has eradicated isolated populations.

Another component of the program aims to prevent introduction of members of the flighted spongy moth complex link from Asia. The Asian species have broader host ranges and the females can fly, so they could spread faster. A multi-nation cooperative program is designed to prevent the moths’ hitchhike on vessels coming from Asia. link APHIS supports this program through negotiations and support of CBP’s offshore vessel inspection, certification, and cleaning requirements. Canada participates in the same program.

In FY 2023, APHIS and state cooperators continued efforts to delimit possibly introductions in Washington State (no additional moths detected); and California and Oregon (initial detections in FY 2020).

California sycamore infested by polyphagous shot hole borer; photo by Beatriz Nobua-Behrmann UC Cooperative Extension

Shot Hole Borers

The report notes that various non-native shot hole borers have been detected in several states. Their hosts include trees in forests and urban landscapes, tea plantations, and avocado orchards. The program’s focus was apparently on the polyphagous and Kuroshio shot hole borers devastating riparian habitats in southern California and urban areas in other parts of California. At California’s request, APHIS and the USDA Forest Service helped establish a working group, led by USFS, with the goal of strategically addressing both shot hole borers in California. In FY 2023, APHIS’ helped with foreign explorations for possible biocontrol agents, as well as host specificity testing.

APHIS leadership told the National Plant Board in July 2024 that it had dropped this entire program due to funding shortfalls.

Specialty Crop Pests

While much of this report concerns pests of agricultural crops (e.g., grapes, citrus, potatoes), it also summarized efforts re: Phytophthora ramorum (sudden oak death) and spotted lanternfly. APHIS says its efforts protected nursery stock production worth approximately $1.3 billion as of 2019, and tree fruit production worth approximately $1.7 billion in 2021.

map showing areas of the Eastern United States at risk to *P. ramorum* – developed by Gilligan of Cambridge University

Phytophthora ramorum

The report states that APHIS seeks to limit P. ramorum’s spread from affected nurseries. The agency does this via regulatory strategies. During FY 2023, 16 nurseries were governed by more stringent rules under the federal program which are imposed on nurseries that have been determined in past years to harbor P. ramorum-infected plants.

In addition, Oregon officials continued surveys of an area outside its quarantine zone because of a detection the previous year. APHIS will adjust the federal quarantine depending on the state’s findings.

The APHIS report does not discuss several pertinent events that occurred in FY2023. [For more details, read the California Oak Mortality Task Force newsletters for 2023 – posted here.

First, APHIS does not mention or discuss the implications of detection of two new strains of P. ramorum — EU1 & NA2 — in west coast forests. The presence of EU1 in a new California county (Del Norte) was confirmed in Feb 2023.

Second, the report said that Oregon is trying to determine the extent of the P. ramorum infection detected outside the state’s quarantine zone. However, it does not mention that this outbreak involves the new NA2 lineage – and that NA2 was known to be present in nurseries in the region since 2005.

The report also does not clarify that three nurseries to added to the more stringent program were so treated because SOD-infected plants were found on their premises.

Nor does the report note that at least two new naturally-infected hosts of P. ramorum were identified: Western sword fern (Polystichum munitum) and Arbutus x ‘Marina’.Koch’s postulates need to be completed on the latter so it has not yet been added to APHIS’ official host list.

Spotted Lanternfly

Spotted Lanternfly (SLF) was found in 16 states in FY 2023. APHIS’ program enjoyed funding provided through Specialty Crop Pests and from the Plant Protection Act’s Section 7721 link ($6 million from the latter).

The report notes that APHIS still does not have enough data to determine SLF’s impacts on agriculture. Thus far, vineyards have been the most adversely affected agricultural segment, mostly due to SLF acting as a stressor to vines. Also, the sticky, sugary “honeydew” produced by SLF attracts other insects and promotes sooty mold growth. These can ruin the fruit and further damage the plant.

SLF populations are strongly linked to major transportation pathways, such as railroads and interstate highways. APHIS targets treatments and, in some areas, removes SLF’s preferred host plant (tree of heaven [Ailanthus]), from transportation hubs. The aim is to reduce the risk of SLF’ spread to new areas and to eradicate isolated infestations. In FY 2023, APHIS and cooperators treated 4,637 properties covering 6,455 acres in affected areas. However, during the National Plant Board meeting both state and APHIS officials complained to me that managers of these transportation hubs raise many barriers to their access, sharply limiting the program’s chance of success.

*Ailanthus altissima* – drive of spotted lanternfly invasion

The program was expanded after National Environmental Policy Act-mandated environmental review. This allowed APHIS to conduct treatments in four additional states—Indiana, Massachusetts, Michigan, and Rhode Island. In addition, program cooperators identified three potential biological control organisms, one that targets the tree of heaven and two that target SLF. APHIS will continue to evaluate them and develop methods to rear them in the laboratory.

Finally, in fiscal year 2023, APHIS joined the National Association of State Departments of Agriculture and the National Plant Board to develop a national strategic plan outlining the future direction of the SLF program. With the strategic plan, PPQ aims to harmonize the approach across states to slow SLF’s spread, develop consistent outreach messaging for a nationwide audience, and more effectively use existing state and Federal resources. Continued spread of SLF despite the huge effort, rising costs of the program, and new scientific findings spurred reconsideration of the strategy.

To summarize, I hope that APHIS’ annual report will – in the future – help members of Congress and their staff understand the agency’s programs’ purpose and past successes. This increased understanding might make it easier to advocate for more funding. I am troubled, however, by the agency’s glossing over significant problems.

Posted by Faith Campbell

www.fadingforests.org

Congress is considering the Farm Bill – help improve it!!!

The House and Senate Agriculture committees are edging toward adopting the next Farm Bill, which is a year past due. Farm bills set policy, funding levels, and more, for 5 years. Each covers a wide range of subjects, including crop subsidies and insurance; food stamps; rural development (including wifi access); forestry policy; and research.

As you might remember, CISP aims to improve USDA’s programs — not only to prevent introductions of non-native tree killing pests and pathogens but also to better respond to those that enter the US and become established. I summarize here what the Senate and House bills have in common and how they differ on these issues.

I understand that the minorities, that is, House Democrats and Senate Republicans, have not accepted all aspects of the majorities’ drafts. So let’s take the opportunity to ask for better bills.

Both the House and Senate bills would “simplify” the USDA Forest Service’s obligations to prepare environmental assessments under the National Environmental Policy Act (NEPA). I have not analyzed which bill weakens NEPA more.

The Senate Bill: The Rural Prosperity and Food Security Act of 2024

The Senate bill addresses forest pest species in several places: Title II — Conservation, Title VII — Research, and Title VIII — Forestry. Here, I describe relevant sections, beginning with the section that partially addresses CISP’s proposal.

Title VIII — Forestry. Section 8214 requires the USDA Secretary to establish a national policy to counter threats posed by invasive species to tree species and forest ecosystems and identify areas for interagency cooperation.

This mandate falls far short of what we sought in a previous bill (S. 1238). However, depending on the exact wording of the bill and accompanying report, perhaps we can succeed in building a stronger program.

It is most important to obtain funding for applied, directed research into resistance breeding strategies, “bulking up,” and planting seedlings that show promise. Please contact your senators and ask them to work with the sponsors – Peter Welch [D-VT], Maggie Hassan [D-NH], and Mike Braun [R-IN] – to try to incorporate more of S. 1238 in the final bill.

The Senate bill contains other provisions that might be helpful for invasive species management – although not part of what CISP and our partners asked for.

‘ōhi‘a trees killed by rapid ‘ōhi‘a death; photo by Richard sniezko, USFS

Title VIII — Forestry. In Section 8506, the Senate bill would require that the US Departments of Agriculture and Interior continue working with Hawai`i to address the pathogen that causes rapid ‘ōhi‘a death. The section authorizes $5 million for each of the coming five fiscal years to do this work. Unfortunately, authorization does not equal funding. Only the Senate and House Appropriations Committees can make this funding available. Hawai`i’s endemic ‘ōhi‘a trees certainly face a dire threat. CISP is already advocating for funding to support resistance breeding and other necessary work.

Title VIII — Forestry. Sections 8247 and 8248 support USDA Forest Service’s nursery and tree establishment programs. My hesitation in fully supporting these provisions is that I fear the urge to plant lots of trees in a hurry will divert attention for the need to learn how to propagate many of the hardwood tree species that have been decimated by non-native pests. However, I agree that the U.S. lacks sufficient nursery capacity to provide anything close to the number of seedlings sought. Perhaps this program can be adjusted to assist the “planting out” component of our request.

Title VII — Research. Section 7208 designates several high-priority research initiatives. On this list are spotted lanternfly, and “invasive species”. A number of forest corporations have been urging Members of Congress to upgrade research on this broad category, which I believe might focus more on invasive plants than the insects and pathogens on which CISP focuses. How the two ideas are integrated will be very important.

Another high-priority initiative concerns the perceived crisis in failed white oak regeneration.

Title VII — Research. Section 7213 mandates creation of four new Centers of Excellence at 1890 Institutions. These are historically Black universities that are also land-grant institutions]. These centers will focus on: 1) climate change, 2) forestry resilience and conservation; 3) food safety, bioprocessing, and value-added agriculture; and, 3) food and agricultural sciences and the social sciences.

Title II — Conservation. Section 2407 provides mandatory funding (which is not subject to annual appropriations) of $75 million per year to the national feral swine eradication/control program (run by USDA APHIS’ Wildlife Service Division). I discuss this program in a separate blog.

The Senate bill also mandates use of several conservation and other programs to address the causes and impacts of climate change. This requirement is directly countered by the House Agriculture Committee’s bill (see below).

The House Bill

Title VIII — Forestry. This section contains none of the provisions CISP’ sought to USDA’s management of tree-killing non-native insects and diseases.

Instead, the House bill calls on the USFS to establish a comprehensive approach to addressing the demise of the giant sequoia trees.

Title VII — Research The House bill, like the Senate’s, lists the invasive species and white oak research initiatives as high priority. The House, unlike the Senate, does not include spotted lanternfly.

Title II — Conservation. As I noted above, the House bill explicitly rescinds all unobligated conservation funding from the Inflation Reduction Act. It reallocates these funds to the traditional conservation programs, e.g., the Environmental Quality Incentive Program and Watershed Protection and Flood Prevention. The bill would use these funds to support “orphan” programs – naming specifically the national feral swine eradication/control program. The House bill provides $150 million – apparently across the five years covered by the Farm Bill, so $30 million per year. Finally, the House allocates 60% of the hog management funds to APHIS, 40% to the Natural Resources Conservation Service.

spotted lanternfly – target of at least 11 projects funded through APHIS’ the Plant Pest and Disease Management and Disaster Prevention Program in FY24. Photo by Holly Raguza, Pennsylvania Department of Agriuculture

Title X —Horticulture, Marketing, and Regulatory Reform. The House’s summary says it is taking steps to protect plant health. It does this by increasing funding for the grant program under the Plant Pest and Disease Management and Disaster Prevention Program – §7721 of the last (2018) Farm Bill. The increase would raise the amount of money available each year from the current level of $70 million to $90 million. These funds are mandatory; they are not subject to annual appropriations. Research, development, and outreach projects funded by this program have certainly added to our understanding of plant pests, hence to their effective management. However, they are usually short-term projects. Therefore they are not suitable for the long-term commitment required for resistance breeding programs. See here and here.

Title III — Trade. Here, the House bill exacerbates the current imbalance between trade promotion and phytosanitary protection. The bill doubles the authorized funding for USDA’s Market Access and Foreign Market Development programs. I concede that this measure probably does reflect a bipartisan consensus in the Congress to support robust programs for promoting agricultural exports.

Also under this Title, the House bill requires the USDA Secretary to conduct regular assessments to identify risks to critical infrastructure that supports food and agriculture sector. This might be helpful – although it is not clear that this assessment would include to threats to forest or urban trees not used commercially (e.g., for timber).

At a recent forum on biological control sponsored by the National Association of State Foresters (NASF), it was reported that participants noted several problems: insufficient funding, significant delays in refilling positions, inadequate research capacity, lack of brick-and-mortar infrastructure, and declining college enrollments in biocontrol-related studies. The NASF Forest Science Health Committee is developing a “Statement of Needs” document that NASF and others can use to lobby for funding to fill these gaps. I hope you will join them in doing so!

salt cedar (*Tamarix* sp.) attacked by biocontrol agent; photo by J.N. Stuart via Flickr

However, as I note above, empowering resistance breeding programs requires a long-term commitment, that is, a comprehensive alteration of policies and infrastructure – beyond annual appropriations.

Posted by Faith Campbell

www.fadingforests.org

U.S. Department of the Interior’s Guidance on Nature-Based Solutions

whitebark pine in Glacier National Park killed by white pine blister rust; National Park Service photo

As I noted in the accompanying blog, the U.S. Department of Interior has also weighed in on how to mitigate climate change as part of the Nation’s response to COP24 of the UN Framework Convention on Climate Change.

Interior’s Nature-Based Solutions “Roadmap” (citation at the end of the blog) is 480 pages long! It includes lots of pictures and extensive lists of examples of various types of projects. The document reviews “nature-based” restoration techniques, the benefits they provide in various realms (ecosystem, economy, social values); and the challenges or barriers likely to be encountered. These analyses cover six types of ecosystems – coastal (further divided into five subgroups), forests, grasslands (two types), inland wetland habitats, riverine habitats (three subgroups), and built environments. The obvious emphasis on aquatic and semi-aquatic habitats reflects the Department’s responsibilities. The threat from invasive species is recognized in each case. Plus there are separate chapters discussing management/removal of invasive pests and pathogens, plants, and vertebrates in all types of ecosystems.

The document’s purpose is to provide Interior’s staff – and others who are interested – with reliable information on determining the conditions and goals under which “nature-based” strategies perform best, the benefits they are likely to provide, instructive examples, and additional resources. Much of the information is intended to help staff persuade skeptics that a “nature-based” approach can solve a climate-related problem, such as sea level rise, as well as, or better than, “grey” infrastructure. This includes discussion of: construction and maintenance costs, efficacy in solving a specific problem, and managing conflicts over land use. Also, it considers benefits to other realms, for example, protecting biodiversity and providing opportunities for recreation and mental and physical well-being.

I will focus on aspects dealing with forests. These occur in several chapters. Each chapter has a brief description of the climate and other services provided by that ecosystem type, followed by sections on ways forward (“Technical Approach”), factors affecting site suitability, tools and training resources, likely benefits and outcomes (economic and ecological), barriers and solutions, and examples of projects.

The forest chapter (Chapter 10) discusses forest conservation and restoration with an emphasis on improving forest health, including fuels management, reforestation, and addressing threats from native and non-native pests. One proposed solution is thinning. This measure is said to enhance tree health and promote invasive plants. The “Roadmap” does not recognize that experts consider thinning is helpful in managing native pests such as mountain pine beetle but not non-native pests.

I was startled to find another suggestion – to plant native tree species that are resistant to non-native pests to restore stands. The “Roadmap” refers readers to the National Park Service Resilient Forests Initiative for Region 1 [which reaches from Virginia to Maine]. The Initiative encourages collaboration among parks with similar issues; provides park-specific resource briefs for 39 parks in the Region; and offers management strategies for a host of problems. These include invasive species control, prescribed fire, deer management, silvicultural treatments, tree planting, and fencing. My confusion is that – as far as I know – there are no sources of trees resistant to the non-native pests plaguing forests of the Northeast, e.g., beech, butternut, chestnut, hemlocks, ash, and oaks.

test planting of pathogen-resistant whitebark pine seedlings in Glacier National Park; photo by Richard Sniezko

In the “Tools” section Chapter 10 lists forest restoration guides published by the U.S. Forest Service (USFS) and the International Union of Forest Research Organizations. The “Examples” section includes a few thinning projects.

Chapter 16 advises on enhancing urban forests, which provide many benefits. The chapter stresses the importance of ensuring that projects’ budgets can support protecting trees from such risks as flooding, fire, pests, disease, “invasive species” (presumably other than insects or pathogens), and climate change. The authors note that urban trees are often more susceptible to pests because of their proximity to human activities that facilitate pests’ spread. However, there is no mention that such pests spread to nearby natural forests. They warn against planting a single tree species. An issue noted but not discussed in detail is the use of non-native species in urban forests, some of which have already become invasive.

Three chapters discuss invasive species per se — insects and pathogens (Chap. 26), plants (Chap 27), and vertebrates (Chap. 28) Each chapter summaries invasion stages and stresses the importance of preventing new introductions, detecting them early, and responding rapidly. Most of the text deals with managing established populations – with the emphasis on applying integrated pest management (IPM). Each raises caveats about biological control agents possibly attacking non-target organisms. Again, the authors emphasize the necessity of ensuring availability of adequate resources to carry out the program.

Chapter 26 addresses Invasive and Nuisance Insects and Pathogens. Examples listed include Asian longhorned beetle, emerald ash borer, hemlock woolly adelgid, spongy moth, Dutch elm disease, sudden oak death, laurel wilt, white pine blister rust, chestnut blight and butternut canker. (All these invaders are profiled under the “invasive species” tab here). The examples also include several native pests, e.g., mountain pine beetle, southern pine beetle, and several pathogens, including Swiss needlecast. I am confused by a statement that priorities for management should be based on pests’ traits; my understanding of the science is that other factors are more important in determining a pest’s impact. See, for example, Lovett et al. 2006.This chapter reiterates the impractical advice to plant trees resistant to the damaging pest. I also wonder at the following statement:

“The process of detection and prevention will need to continue over time to prevent reintroductions or reinvasions of nuisance or invasive pests and pathogens. In some cases, long-term management will be required to contain and prevent spread.” [p. 425] I believe long-term management will required in all cases!

The tools listed in the chapter include various DOI websites re: training and funding; the USDA website listing states’ plant diagnostic laboratories; a USDA IPM “road map”; The Nature Conservancy’s guidebook for assessing and managing invasive species in protected areas; the DOI Strategic Plan; and the University of Georgia’s Center for Invasive Species and Ecosystem Health.

Chapter 27 discusses invasive and nuisance plants. It starts by noting that an estimated 5,000 non-native plant species are stablished in the US. While not all are invasive, there is still potential for these plants to spread and cause harm. The authors state that controlling such plants reduces fire risk and lowers demand for water in arid areas.

The authors say early management is crucial to eradicate or control invasive plant species. Because plant invasions cross property lines, agencies must form partnerships with other agencies and private landowners. Because invasive and nuisance plant species are so widespread, managers must set priorities. The “Roadmap” suggests focusing on sites at the highest risk, e.g., heavily trafficked areas. Continued effort will be necessary to prevent reinvasions or reintroductions. However, long-term management and containment can be incredibly costly and labor-intensive.

lesser celandine invade bottomlands of Delaware Water Gap National Recreation Area

The “Roadmap” complains that many invasive and nuisance plant species are still offered for sale; in fact, that this is the primary pathway by which invasive plants enter the US, (While which we have known this for decades, it is encouraging to see a U.S. government report say: “Advocating for federal regulation and cohesive local policies for preventing invasive [plant] sales is essential to avoid disjointed state rulings.” – even if it does not specify which agencies should take the lead.

In the “Tools” section the chapter lists two USFS guides on managing invasive plants; two California Invasive Plant Council guides; the Interior Department’s 2021 Invasive Species Strategic Plan; EDDMapS (a University of Georgia site on which members of the public can report invasive species); and the TNC guidebook for Assessing and Managing Invasive Species in Protected Areas.

Chapter 28 addresses invasive & nuisance vertebrates (called “wildlife”). It notes that invasive animals are present in more than half of all US National parks. It briefly mentions the Lacey Act as providing legal power to curb the introduction and spread of these animals. It does not discuss strengths and weaknesses of this statute, both of which are substantial. This chapter repeats the odd wording from the pest and pathogen chapter – that in some cases long-term management will be required to contain and prevent spread of invasive species. I find it doubtful that short-term actions will be effective in virtually all cases.

Tools listed include Interior guides on IPM, funding sources, and protecting aquatic systems along with the Department of Interior’s 2021 Invasive Species Strategic Plan. Other tools include the USDA guide on IPM, EDDMapS, and the TNC guidebook.

Forests were also mentioned in the discussion of assisted migration of coastal wetlands to avoid drowning by rising seas (Chapter 1). The text notes that forests upland from coastal wetlands might be killed – either as a result of waterlogging as sea levels rise or as deliberate action to make room for the new marsh. Mortality in either case will reduce carbon sequestration. The authors also note the probability that invasive plants – shrubs in the woods, Phragmites on the edge of the wetland — will be present and have to be controlled.

SOURCES

Lovett, G.M, C.D. Canham, M.A. Arthur, K.C. Weathers, R.D. Fitzhugh. 2006. Foret Ecosystem Responses to Exotic Pests and pathogens in Eastern North America. BioScience Vol 56 No. 5 May 2006.

Warnell, K., S. Mason, A. Siegle, M. Merritt, & L. Olander. 2023. Department of the Interior Nature-Based Solutions Roadmap. NI R 23-06. Durham, NC: Nicholas Institute for Energy, Environment & Sustainability, Duke University. https://nicholasinstitute.duke.edu/publications/department-interior-nature-based-solutions-roadmap.

Posted by Faith Campbell

www.fadingforests.org

What do “Self-Introduced” & “Door-Knocker” Species Tell Us?

*Woldstedtius flavolineatus* – one of at least 13 taxa of non-native ichneumonid wasps established in restoration forests in Hawaiian Forest National wildlife rfefuge; photo by Torgrim Breiehagen for the Norwegian Biodiversity Information Centre; via Wikipedia

As we know, non-native insects and pathogens pose a significant and accelerating threat to biodiversity in forests and other ecosystems. They undermine some conservation programs and reduce ecosystem services and quality of life in urban areas. Nevertheless, damaging introductions continue.

Two recent articles have advocated accelerating biocontrol programs. These articles have reminded us of ongoing failures of international and national biosecurity programs, including that of the US. The articles also make interesting suggestions regarding ways to be more pro-active in preventing introductions.

1. “Self-introductions” of invaders’ enemies

Weber et al. (full citation at end of blog) provide many examples of unintentional “self-introductions” of natural enemies of arthropod pests and invasive plants. In fact, “self-introductions” of natural enemies of arthropod pests might exceed the number of species introduced intentionally. These introductions have been facilitated by the usual factors: the general surge in international trade; lack of surveillance for species that are not associated with live plants or animals; inability to detect or intercept microorganisms; huge invasive host populations that allow rapid establishment of their accidentally introduced natural enemies; and lack of aggressive screening for pests already established.

Among the examples illustrating failures of biosecurity programs:

Across six global regions, nearly two-thirds of parasitoid Hymenoptera species were introduced unintentionally. The proportion varies significantly by region. For example, four-fifths of these insects in New Zealand arrived accidentally.
The unintentional spread of the glassy-winged sharpshooter (Homalodisca vitripennis) and a biocontrol agent Cosmocomoidea ashmeadi has been so rapid among islands in the Pacific Ocean (including Hawai`i) they are considered ‘biomarkers’ of biosecurity failures.
Regarding the United States specifically, an estimated 67% of beneficial insects introduced to Hawai`i and 64% of parasitoid Hymenoptera introduced to the mainland U.S. were accidental “self-introductions.”

Weber et al. consider their figures to be underestimates. The situation is particularly uncertain regarding pathogens that kill arthropods. Many microbial species are not yet described.

spotted lanternfly; photo by Stephen Ausmus, USDA

In some cases, these “self-introduced” arthropods have proved beneficial. Two examples are Entomophaga maimaiga and Lymantria dispar nucleopolyhedrovirus (LdNPV), which help control the spongy moth (Lymantria dispar). In other cases the “self-introduced” creatures are pests themselves. A prominent example is the invasion by the spotted lanternfly (Lycorma delicatula). This was facilitated by the widespread presence of the highly invasive plant Ailanthus altissima. It illustrates what Weber et al. call “receptive bridgehead effects.” That is, once an invasive pest is well-established, the chance that its natural enemies will find a suitable host and also establish in the pest’s invaded range is much higher.

Weber et al. reaffirm that there are many good reasons not to allow such random invasions of diverse non-native species – including their natural enemies. Deliberately introduced biocontrol agents are chosen after determining their efficacy, host-specificity, and climatic suitability. Random introductions, on the other hand, might favor generalist species, which could threaten non-target species. Accidental introductions might also be accompanied by pathogens and hyperparasitoids that could compromise the efficacy of biocontrol agents.

In short, unintentionally introduced natural enemies might have about the same level of success in controlling the target pest’s populations as do intentionally introduced agents. However, unintentional introductions of both pests and pathogens carry additional risks of non-target impacts and contamination with their own natural enemies that would hamper the efficacy of the biocontrol agent. Weber et al. conclude that delays in releasing a deliberately chosen and evaluated biocontrol agent reduce the probability that it will successfully establish instead of an unintentionally introduced organism.

cactus moth larva on *Opuntia*; photo by Doug Beckers via Flickr

It is especially likely that an arthropod – whether or not a biocontrol agent – will spread within a geographic region. Weber et al. say both the U.S. and Canada have received more than a dozen species intentionally introduced into the other country. They also cite spread of the cactus moth, Cactoblastis cactorum, into Florida from several Caribbean countries. The cactus moth has spread and now threatens the center of diversity of flat-padded Opuntia cacti in the American southwest and Mexico.

Another example is California: 44% of invading terrestrial macroinvertebrates that have established in the state came from populations established elsewhere in the US and Canada (Hoddle 2023). This number exceeds the total number of invasive macroinvertebrates in the state that originated anywhere in Eurasia (Weber et al.).

True, it is very difficult to prevent natural spread. But a lot of this spread is facilitated by human activities, e.g., transporting vectors such as living plants, firewood, outdoor furniture or storage “pods.” I have complained often — here and here and here — that interstate movement of invasive plant pests is particularly poorly controlled.

Some scientists and regulators have responded to these situations by improving phytosanitary programs. California officials, in 2019, set up a program to fund projects aimed at developing integrated pest management strategies for species thought to have a high invasion potential before they arrive. I urge other states to do the same. This would probably be most effective in controlling the target species – and in relation to cost — if developed by regional consortia.

Weber et al. suggest that given continuing unintentional introductions of non-native species, phytosanitary agencies need to focus on those invasion pathways that are particularly likely to result in invasions, e.g. live plants, raw lumber (including wood packaging), and bulk commodities e.g. quarried rock.

The authors also suggest research opportunities that arise from biocontrol agents’ “self-introductions”. These include:

Comparing actual host ranges to those predicted by laboratory and other studies;
Quantifying the role of Allee effects, for example by studying the spread of the glassy-winged sharpshooter and its biocontrol agent across the Pacific region;
Using molecular analyses to disentangle multiple routes of entry (e.g., the “invasive bridgehead effect”) and hybridization.

2. Door-knocker species

Hoddle (2023) suggests further that early detection programs should focus on “door-knocker” species — those likely to enter and cause significant negative impacts. In an earlier article (Hoddle, Mace and Steggall 2018) argued that the benefits of a pro-active biocontrol program outweigh the costs. The authors say the information gained would cut the time needed to deploy effective biocontrol. Ultimately, this could reduce the prolonged and even irreversible ecological and economic disruption from invasive pests, associated pesticide applications, and lost ecological services.

Asian citrus psyllid (*Diaphorina citri*); USDA photo by Justin Wendell; Hoddle cites this species as one that a pro-active biocontrol program should have targetted

Hoddle calls funding pro-active biocontrol research programs before they’re needed as analogous to buying insurance. The owners of insurance policies hope not to need them but benefit when catastrophe strikes. Furthermore, the information gained from early research might identify natural enemy species that could “self-introduce” along with the invading host. Finally, proactive research might clarify whether the increasing number of natural enemy species that are “self-introducing” pose a threat to non-target organisms.

Recognizing the difficulty of identifying an “emerging invasive species” before its introduction, Hoddle endorses other components of prevention programs:

Collaborating with non-U.S. scientists to identify and mitigate invasion bridgeheads. Such efforts would both lessen bioinvasion threats and possibly aid in determining native ranges and facilitating location of natural enemies.
Sentinel plantings, such as those established under the International Plant Sentinel Network. These plantings can also support research on natural enemies of key pests.
Integrating online platforms, networks, professional meetings, and incursion monitoring programs into “horizon scans” for potential invasive species. He mentions specifically PestLens; online community science platforms, e.g., iNaturalist; international symposia; and official pest surveillance, e.g., U.S. Forest Service’s bark beetles survey and surveys done by the California Department of Food and Agriculture and border protection stations.

date palm mealybug (*Pseudaspidoproctus hyphaeniacus*); threat to native *Washingtonia* palms of California; one of pests tracked by PestLens

Weber et al. also support the concept of sentinel plant nurseries – especially because accidental plant and herbivore invasions often occur at the same points of entry.

Both Weber et al. and Hoddle urge authorities not to strengthen regulations governing biocontrol introductions. Weber et al. say that would be to make perfect the enemy of the good. The need is to balance solving problems with avoiding creation of new problems.

SOURCES

Hoddle, M.S., K. Mace, J. Steggall. 2018. Proactive biological control: A cost-effective management option for invasive pests. California Agriculture. Volume 72, No. 3

Hoddle. M.S. 2023. A new paradigm: proactive biological control of invasive insect pests. BioControl https://doi.org/10.1007/s10526-023-10206-5

Weber, D.C. A.E. Hajek, K.A. Hoelmer, U. Schaffner, P.G. Mason, R. Stouthamer, E.J. Talamas, M. Buffington, M.S. Hoddle, and T. Haye. 2020. Unintentional Biological Control Chapter for USDA Agriculture Research Service. Invasive Insect Biocontrol and Behavior Laboratory. https://www.ars.usda.gov/research/publications/publication/?seqNo115=362852

Posted by Faith Campbell

www.fadingforests.org

Invasive Tree Species in the U.S. Caribbean: New Attention!

African Tulip Tree (*Spathodea campanulata*) on Puerto Rico; photo by Joe Schlabotnik via Flickr

While it is widely accepted that tropical island ecosystems are especially vulnerable to invasions, there has been little attention to terrestrial bioinvaders in the Caribbean; there has been more attention to marine bioinvaders such as lionfish. I am glad that is starting to change. Here I review a new study by Potter et al. (full citation at end of this blog), supplemented by information from other recent studies, especially Poland et al.

Potter et al. used USFS Forest Inventory and Analysis (FIA) survey data to examine regeneration rates by non-native tree species introduced to the continental United States, Hawai`i, and Puerto Rico. I rejoice that they have included these tropical islands, often left out of studies. They are part of the United States and are centers of plant endemism!

Potter et al. sought to learn which individual non-indigenous tree species are regenerating sufficiently to raise concern that they will cause significant ecological and economic damage in the future. That is, those they consider highly invasive. They defined such species as those for which at least 75% of stems of that species detected by FIA surveys are in their small tree categories – saplings or seedlings. They concluded that these species are successfully reproducing after reaching the canopy so they might be more likely to alter forest ecosystem functions and services. They labelled species exhibiting 60 – 75% of stems in the “small” categories as moderately invasive.

The authors recognize that many factors might affect tree species’ regeneration success, especially at the stand level. They assert that successful reproduction reflects a suite of factors such as propagule pressure, time since invasion, and ability of a species to adapt to different environments.

As I reported in an earlier blog, link 17% of the total flora of the islands of the Caribbean archipelago – including but not limited to Puerto Rico – are not native (Potter et al.). In Puerto Rico, two-thirds of forests comprise novel tree assemblages. The FIA records the presence of 57 non-native tree species on Puerto Rico. Potter et al. identified 17 non-native tree species as highly invasive, 16 as potentially highly invasive, and two as moderately invasive. That is, 33 of 57 nonnative tree species, or 58% of those species tallied by FIA surveyors, are actual or potential high-impact bioinvaders. While on the continent only seven non-native tree species occurred on at least 2% of FIA plots across the ecoregions in which they were inventoried, on Puerto Rico 21 species occurred on at least 2% of the FIA plots (38%). They could not assess the invasiveness of the eight species that occurred only as small stems on a couple of survey plots. These species might be in the early stages of widespread invasion, or they might never be able to reproduce & spread.

The high invasion density probably reflects Puerto Rico’s small size (5,325 mi² / 1,379,000 ha); 500 years of exposure to colonial settlement and global trade; and wide-scale abandonment of agricultural land since the middle of the 20^th Century

Naming the invaders

The most widespread and common of the highly invasive non-native tree species are river tamarind (Leucaena leucocephala), on 12.6% of 294 forested plots; algarroba (Prosopis pallida) on 10.9%; and African tuliptree (Spathodea campanulata)on 6.1%. Potter et al. attribute the prevalence of some species largely to land-use history, i.e., reforestation of formerly agricultural lands. In addition, some of the moderately to highly invasive species currently provide timber and non-timber forest products, including S. campanulata, L. leucocephala, Syzgium jambos (rose apple) and Mangifera indica (mango).

Potter et al. contrast the threat posed by Spathodea campanulata with that posed by Syzgium jambo. The latteris shade tolerant and can form dense, monotypic stands under closed canopies. Because it can reproduce under its own canopy, it might be able to remain indefinitely in forests unless it is managed. In contrast S. campanulata commonly colonizes abandoned pastures. Since it is shade intolerant, it might decline in the future as other species overtop it. Meanwhile, they suggest, S. campanulata might provide habitat appropriate for the colonization of native tree species.

Second-growth forest in Caribbean National Forest “El Yunque”

Poland et al. say the threat from Syzgium jambos might be reduced by the accidentally introduced rust fungus Puccinia psidii (= Austropuccinia psidii), which has been killing rose apple in Puerto Rico. In Hawai`i, the same fungus has devastated rose apple in wetter areas.

Potter et al. note that stands dominated by L. leucocephala and Prosopis pallida in the island’s dry forests are sometimes arrested by chronic disturbance – presumably fire. However, they do not report whether other species – native or introduced – tend to replace these two after disturbance. The authors also say that areas with highly eroded soils might persist in a degraded state without trees. The prospect of longlasting bare soil or trashy scrub is certainly is alarming.

Potter et al. warn that the FIA’s sampling protocol is not designed to detect species that are early in the invasion process. However, they do advise targetting eradication or control efforts on the eight species that occurred only as small stems on a couple of survey plots. While their invasiveness cannot yet be determined, these species might be more easily managed because presumably few trees have yet reached reproductive age. They single out Schinus terebinthifolius (Brazilian pepper), since it is already recognized as moderately invasive in Hawai`i. I add that this species is seriously invasive in nearby peninsular Florida and here! APHIS recently approved release of a biocontrol insect in Florida targetting Brazilian pepper. It might easily reach nearby Puerto Rico or other islands in the Caribbean. I am not aware of native plant species in the Caribbean region that might be damaged by the biocontrol agent. However, two native Hawaiian shrubs might be harmed if/when this thrips reaches the Hawaiian Islands. Contact me for specifics, or read the accompanying blog about Potter et al. findings in Hawai`i.

Poland et al. looked at the full taxonomic range of possible bioinvaders in forest and grassland ecosystems. The Caribbean islands receive very brief coverage in the chapter on the Southeast (see Regional Summary Appendices). This chapter contains a statement that I consider unfortunate: “Introduction of species has enriched the flora and fauna of Puerto Rico and the Virgin Islands.” The chapter’s authors assert that many of the naturalized species are restoring forest conditions on formerly agricultural lands. They say that these islands’ experience demonstrates that introduced and native species can cohabitate and complement one another. I ask – but in what kind of forest? These forests, are novel communities that bear little relationship to pre-colonial biodiversity of the islands. Was not this chapter the right place to note that loss? Forests are more than CO₂sinks.

I also regret that the chapter does not mention that the Continental United States can be the source of potentially invasive species (see several examples below).

Mealybug-infested cactus at Cabo Rojo National Wildlife Refuge, Puerto Rico. Photo by Yorelyz Rodríguez-Reyes

The chapter does concede that some introduced species are causing ecological damage now. See Table A8.1. Some of these troublesome introduced species are insects:

the South American Harrisia cactus mealybug (Hypogeococcus pungens) is killing columnar cacti in the islands’ dry forests. The chapter discusses impacts on several cactus species and control efforts, especially the search for biocontrol agents.
the agave snout weevil (Scyphophorus acupunctatus), native to the U.S. Southwest and Mexico , is threatening the endemic and endangered century plant (Agave eggersiana) in St. Croix & Puerto Rico.
Tabebuia thrips (Holopothrips tabebuia) is of unknown origin. It is widespread around mainland Puerto Rico. Its impacts so far are primarily esthetic, but it does apparently feed on both native and introduced tree species in the Tabebuia and Crescentia genera.

The Caribbean discussion also devotes welcome attention to belowground invaders, i.e., earthworms. At least one species has been found in relatively undisturbed cloud forests, so it is apparently widespread. Little is known about its impact; more generally, introduced earthworms can increase soil carbon dioxide (CO₂) emissions as through speeded-up litter decomposition and soil respiration.

A factsheet issued by the British forestry research arm DEFRA reports that the pine tortoise scale Toumeyella parvicornis has caused the death of 95% of the native Caicos pine (Pinus caribaea var. bahamensis) forests in the Turks and Caicos Islands (a UK Overseas Territory). The scale is native to North America. It has recently been introduced to Italy as well as to Puerto Rico, and the Turks and Caicos Islands.

SOURCES

Lugo, A.E., J.E. Smith, K.M. Potter, H. Marcano Vega, C.M. Kurtz. 2022. The Contribution of Non-native Tree Species to the Structure & Composition of Forests in the Conterminous United States in Comparison with Tropical Islands in the Pacific & Caribbean. USFS International Institute of Tropical Forestry General Technical Report IITF-54.

Poland, T.M., Patel-Weynand, T., Finch, D., Miniat, C. F., and Lopez, V. (Eds) (2019), Invasive Species in Forests and Grasslands of the United States: A Comprehensive Science Synthesis for the United States Forest Sector. Especially the Appendix on the Southeast and Caribbean. Springer Verlag. Available gratis at https://link.springer.com/book/10.1007/978-3-030-45367-1

Potter K.M., Riitters, K.H. & Guo. Q. 2022. Non-nativetree regeneration indicates regional & national risks from current invasions. Frontiers in Forests & Global Change Front. For. Glob. Change 5:966407. doi: 10.3389/ffgc.2022.966407

Posted by Faith Campbell

www.fadingforests.org

Support House & Senate bills to Enhance Response to Forest Pests

white ash: a species that might be restored under the programs envisioned in the proposed bills

Bills have been introduced into both the House and Senate to enhance USDA APHIS and Forest Service programs intended to curtail introduction and spread of non-native forest pests and disease and – especially – programs aimed at restoring pest-decimated trees to the forest.

The House bill is H.R. 3174; it was introduced by Reps. Becca Balint (VT).

The Senate bill is S. 1238; it was introduced by Senators Peter Welch (VT), Mike Braun (IN), and Maggie Hassen (NH). [Both senators Welch and Braun are on the Agriculture Committee – which will write the bill.]

CISP hopes that the contents of these two bills will be incorporated in the Farm Bill that Congress is expected to adopt this year or next. The proposals have the support of the Forests in the Farm Bill coalition. [Unfortunately, neither the “Consolidated Recommendations” nor “Summarized Recommendations appears to be posted on the internet at present.]

In the last Congress, a nearly identical bill introduced by then-Representative Peter Welch was endorsed by the organizations listed below. We hope they will endorse the new bills now! If you are a member of one of these organizations, please ask them to do so.

Organizations that endorsed the previous bill: Vermont Woodlands Association, American Forest Foundation, Center for Invasive Species Prevention, Reduce Risk from Invasive Species Coalition, National Woodland Owners Association (NWOA), National Association of State Foresters (NASF), The Society of American Foresters (SAF), the North American Invasive Species Management Association (NAISMA), the Ecological Society of America, Entomological Society of America, a broad group of university professors and scientists, The Nature Conservancy (TNC) Vermont, Audubon Vermont, the Massachusetts Forest Alliance, the New Hampshire Timberland Owners Association, the Maine Woodland Owners Association, and the Pennsylvania Forestry Association.

I seek your help in generating support for incorporating these proposals into the 2023 Farm Bill. Please urge your representative and senators to co-sponsor the bills or otherwise support that action.

beech in a breeding experiment at The Holden Arboretum; photo by Jennifer Koch

Key points of the two bills:

They strengthen APHIS’ access to emergency funds. APHIS has had the authority to access emergency funds from the Commodity Credit Corporation since 2000. However, the Office of Management and Budget has often blocked its requests. See § 2, of the bills, EMERGENCY AUTHORITY WITH RESPECT TO INVASIVE SPECIES.
It creates two separate but related grant programs.
- The first grant program – in § 3. FOREST RECLAMATION GRANTS – funds research addressing specific questions impeding the recovery of tree species that are native to the US and have suffered severe levels of mortality caused by non-native plant pests or noxious weeds.
- The second grant program – in § 4. FOREST RESTORATION IMPLEMENTATION GRANTS – funds implementation of projects to restore these pest-decimated tree species to the forest. These projects must be part of a forest restoration strategy that incorporates a majority of the following components:

(1) Collection and conservation of native tree genetic material.

(2) Production of propagules of the target tree species in numbers sufficient for landscape-scale restoration.

(3) Preparation of planting sites in the target tree species’ former habitats.

(4) Planting of native tree seedlings.

(5) Post-planting maintenance of native trees.

§ 5 states that the absence of a national policy on addressing nonnative forest pests has resulted in their receiving a low priority within all Federal agencies. It then mandates a study to analyze agencies’ available resources, raise the issue’s priority, and improve coordination among agencies. This study is to be carried out by an independent institution, for example the National Academy of Sciences. The authors are to consult with specialists in entomology, genetics, forest pathology, tree breeding, forest and urban ecology, and invasive species management.
Funding for all three action components – the emergency response and both grant programs – would come from the Commodity Credit Corporation, so it would not be subject to the vagaries of annual appropriations bills.

Forest Restoration Alliance volunteers potting hemlock seedlings; photo provided by Fred Hains

Entities which could apply for the research grants (§ 3 of the bills) include Federal agencies; State cooperative institutions; academic institutions offering degrees in the study of food, forestry, and agricultural sciences; and non-profit organizations exempt from taxes under §501(c)(3) of the tax code. Types of research funded could include:

‘‘(A) biocontrol of nonnative pests & diseases or noxious weeds severely damaging native tree species [the bill does not specify, but Project CAPTURE identifies many qualifying species; see also my earlier blog];

‘‘(B) exploration of genetic manipulation of the plant pests or noxious weeds;

‘‘(C) enhancement of pest-resistance mechanisms of hosts; and

‘‘(D) development of other strategies for restoring individual tree species.

The maximum amount of such grants is $400,000 per year.

Entities which could apply for the implementation grants (§ 4 of the bills) include a cooperating forestry school; a land-grant college or university; a State agricultural experimental station; a 501(c)(3) organization. Funding would begin at $3 million for FY 2023 and rise to $10 million for FY 2026.

The Secretary of Agriculture would be guided in implementing these programs by two committees. One – the committee of experts – would constitute representatives of the USFS, APHIS, ARS & State forestry agencies. The second – the advisory committee – would be composed of representatives of land-grant colleges and universities and affiliated State agriculture experiment stations, forest products industry, recreationists, and professional forester, conservation, and conservation scientist organizations.

Port-Orford cedar seedlings at USFS Dorena Center – a model for success! Photo provided by Richard Sniezko

Please contact your Member of Congress (Representative) and senators to urge them to support inclusion of these provisions in the Farm Bill. [Remember: they work for us!] Telling them of your support for these bills is especially important if your Representative or Senator is on the Agriculture Committee. I list those legislators here:

State	HOUSE AGRIC COMM	SENATE AGRIC COMM
AL	Barry Moore	Tommy Tuberville
AR	Rick Crawford	John Boozman
CA	Doug Lamalfa John Duarte Jim Costa Salud Carbajal
CO	Yadira Caraveo	Michael Bennet
CT	Jahana Hayes
FL	Kat Cammack Darren Soto
GA	Austin Scott David Scott Sanford Bishop	Raphael Warnock
HI	Jill Tokuda
IA	Randy Feenstra Zach Nunn	Joni Ernst Charles Grassley
IL	Mike Bost Mary Miller Nikki Budzinski Eric Sorensen Jonathan Jackson	Richard Durbin
IN	Jim Baird	Mike Braun
KS	Tracey Mann Sharice Davids	Roger Marshall
KY		Mitch McConnell
MA	Jim McGovern
ME	Chellie Pingree
MI	Elissa Slotkin	Debbie Stabenow
MN	Angie Craig	Amy Klobuchar Tina Smith
MO	Mark Alford
MS	Trent Kelly	Cindy Hyde-Smith
NC	David Rouzer Alma Adams
ND		John Hoeven
NE	Don Bacon	Deb Fischer
NJ		Cory Booker
NM	Gabe Vasquez	Ben Ray Lujan
NY	Marc Molinaro Nick Langworthy	Kirsten Gillibrand
OH	Max Miller Shontel Brown	Sherrod Brown
OK	Frank Lucas
OR	Lori Chavez-Deremer Andrea Salinas
PA	Glenn Thompson	John Fetterman

SD	Dusty Johnson	John Thune
TN	Scott Desjarlais Brad Finstad
TX	Ronny Jackson Monica de la Cruz Jasmine Crockett
VA	Abigail Spanberger
VT	Peter Welch
WA	Marie Gluesenkamp Perez
WI	Derrick van Orden

Posted by Faith Campbell

www.fadingforests.org

Protecting ash & hemlock – latest information

nearly dead ash in Shenandoah National Park; photo by F.T. Campbell

I participated in the annual USDA Interagency Invasive Species Research Forum in Annapolis in January 2023; as usual, I learned interesting developments. I focus here on updates re: efforts to protect ash and hemlock

Hopeful Developments re: countering EAB to protect ash

There are hopeful results in both the biocontrol and resistance breeding programs. The overall goal is to maintain ash as a viable part of the North American landscape.

Biocontrol

Juli Gould (APHIS) reminded us that the agency began a classical biocontrol program targetting emerald ash borer (EAB) in 2003 – only a year after EAB had been detected and much earlier than is the usual practice. [Thank you, former APHIS PPQ Deputy Administrator Ric Dunkle!] By 2007 scientists had identified, tested, and approved three agents; a fourth was approved in 2015.

Nicole Quinn (University of Florida) stressed that the egg prarasitoid, Oobius — if it is effective — could prevent EAB from damaging trees. However, it is so small that it is very difficult to sample. One small study demonstrated that Oobius will parasitize EAB eggs laid in white fringe trees (Chionanthus virginicus) as well as in ash. This is important because it means this secondary host is not likely to be a reservoir of EAB.

The numbers

According to Ben Slager (APHIS), more than 8 million parasitoids have been released at 950 sites since the program began in 2007. These releases have been in 418 counties in 31 states, DC, and four Canadian provinces. Still, these represent just 28% of infested counties. Parasitoids have been recovered in 21 states and two provinces.

Rafael de Andrade (University of Maryland) specified that these releases included more than 5 million Tetrastichus in 787 sites; ~2.5 million Oobius in 828 sites in 30 states; ~500,000 Spathius agrili – lately only north of the 40^th parallel. Releases of Spathius galinae began in 2015; so far ~ 470,000 in 395 sites.

Impact

Several presenters addressed questions of whether the agents are establishing, dispersing, and – most important – improving ash survival. Also, can classical biocontrol be integrated with other management techniques, especially use of the pesticide emamectin benzoate.

Dispersal

Several studies have shown that the four biocontrol agents disperse well (with the caveat that Oobius is very difficult to detect so its status is much less certain).

Implementation considerations

De Andrade found that the longer the delay between the date when EAB was detected and release of Oobius, the less likely Oobius will be recovered. Tetrastichus surprised because the higher the numbers released, the fewer were recovered. He could determine no association between recovery of S. agrili and variations in release regime [numbers released; delay in releasing biocontrol agents; or frequency of releases]. He said it is too early to assess Sp. galinae since releases began only in 2015, but he did see expected relationship to propagule pressure – the more wasps released, the higher the number that were recovered. Sp. galinae did surprise in one way: it seemed to perform better at lower latitudes. De Andrade noted he was working data from less than half of release sites. He asked collaborators to submit data!!!!

Initial signs of ash persistence and recovery

Claire Rutledge (Connecticut Agriculture Experiment Station) determined that

More large trees were surviving in plots where the biocontrol agents were released
EAB density was lower at long-invaded sites
Parasitism rates were similar across release age treatments and release/control plots

Gould focused on protecting saplings so they can grow into mature trees which could be sources of seeds to establish future generations. She noted that there are many “aftermath” forests across the northern United States – those dominated by ash saplings.

In Michigan, at a site of green ash, as of 2015 – 2021, EAB populations are still low, parasitism rate by Tetrastichus and S. galinae high. The percentage of saplings that remained healthy was greater than 80%. There were similar findings in white ash in New York: very low EAB larval density; and more than 70% of ash saplings had no fresh galleries. Gould reported that Tetrastrichus impcts could be detected within three years of release.

So, EAB are being killed by the biocontrol agents combined with woodpecker predation; but in their fourth instar, after considerable damage to the trees.

downy woodpecker in Central Park, NYC. photo by Steven Bellovin, Columbia University

Jian Duan reported on two long-term studies in green & white ash in Michigan and New England. His team used the most labor-intensive but best approach to determine EAB larval mortality and the cause – debarking trees – to determine whether the EAB larva were parasitized, were preyed on by woodpeckers, or were killed by undetermined cause, such as tree resistance, disease, or competition. In Michigan, he linked a crash of EAB population in 2010 was caused by Tetrastichus; EAB tried to recover, but crashed again, due to S. galinae. EAB larval densities had been reduced to 10 / m². Predation by abundant woodpeckers and the native parasitoid Atanycolus was also important.

In New England, EAB has also declined from 20-30 larvae /m² to ~ 10 m².

In Michigan, healthy ash with dbh of larger than 5 inches were much more plentiful in sites where parasitoids had been released. Their survival/healthy rate also was much higher in release sites but the difference declined as years passed. In New England there were growing numbers of healthy trees in 2021-22; (almost none in 2017). Duan conceded that he could not prove a direct link but the data points to recovery.

Tim Morris (SUNY-Syracuse) found that white ash saplings continued to die in large numbers, but the mortality rate was significantly below the rate in 2017. Canopy conditions varied; some trees that were declining in 2013 were recovering in 2017. Forty percent of “healthy” ash in 2013 continued recovering in 2021. Few living trees were declining; trees were either healthy or dead. He thinks probably a combination of genetics and presence of parasitoids explains which trees recover. Morris also reported some signs of regeneration.

beaver feeding on ash saplings, Fairfax County, Va;
photo by F.T. Campbell

At this point, I noted that in parts of northern Virginia, beavers have killed ash saplings. Morris reported finding the same in some sites in New York. Perhaps others have, also; my comment was greeted by laughter.

Theresa Murphy (APHIS) looked at integration of biocontrol and insecticide treatment in urban and natural sites. A study of black and green ash in Syracuse, NY Naperville, IL, and Boulder, CO found continued high parasitism by Tetrasticus and S. galinae and woodpecker attacks in trees treated with emamectin benzoate. Researchers could not detect Oobius. By 2020, most of the untreated trees had died but treated trees remained healthy.

Murphy has begun studying integration of biocontrol and pesticides in green and black ash forests. The goal is to protect large trees to ensure reproduction; the biocontrol agents do not yet protect the large trees. This is especially important for black ash because it declines very quickly after EAB invades. Sites have been established in New York, through collaboration with New York parks, Department of Environmental Conservation, and the Mohawk tribe. She is still looking for sites in Wisconsin – where EAB is spreading more slowly than expected.

1 of the infested ash in Oregon; photo by Wyatt Williams, ODF

Max Ragozzino of the Oregon Department of Agriculture reported on imminent release of biocontrol agents targetting the recently detected outbreak there. I am encouraged by the rapid response by both the state and APHIS.

EAB resistance in ash

Jennifer Koch (USFS) said the goal is not to produce populations where every seedling is fully EAB-resistant, but to develop populations of ash trees with enough resistance to allow continued improvement through natural selection while retaining sufficient genetic diversity to adapt to future stressors (changing climate, pests, diseases). The program has developed methods to quantify resistance in individuals.. Initial field selections of “lingering ash” were shown to be able to kill as many as 45 % of EAB larvae. Already green ash seedling families have been produced by breeding lingering ash parents. This first generation of progeny had higher levels of resistance, on average, than the parent trees. Each generation of breeding can increase the proportion of resistance. Although the bioassays to test for EAB-resistance are destructive (e.g., cutting and peeling to count numbers of surviving larvae), the potted ash seedling stumps can resprout. Once the new sprouts are big enough they are planted in field trials to correlate bioassay results with field performers. Poor performers are culled; those with higher levels of resistance remain and become sources of improved seed.

To ensure preservation of local adaptive traits, this process must be repeated with new genotypes to develop many seed orchards from across the species’ wide range. To support this work, concerned scientists are building multi-partner collaborative breeding networks. These organizations provide ways for citizens and a variety of partners to engage through monitoring and reporting lingering ash, making land available for test planting, and helping with the work of propagation.

See Great Lakes Basin Forest Health Collaborative » Holden Forests & Gardens (holdenfg.org), Monitoring and Managing Ash (MaMA) – A citizen-science-driven program for conservation and mitigation (monitoringash.org), and TreeSnap – Help Our Nation’s Trees! for more information.

Resistance levels in some of the first generation progeny were high enough for use in horticulture, where it is important that trees can remain healthy in challenging environments (street trees, city parks, landscaping, etc.). Koch hopes to develop about a dozen cultivars comprising the best-performing trees, appropriate for planting in parts of Ohio, Michigan, Indiana, and Pennsylvania. Local NGO partners are planting some of these promising genotypes in Detroit to see how they withstand EAB attack.

The threat to black ash is especially severe, and this species presents unique difficulties. While scientists found several seedlings from unselected seedlots had killed high levels of larvae, those deaths did not always result in better tree survival. Koch thinks the tree’s defense response becomes detrimental to tree by blocking transport of water and nutrients. She is working with experts in genomics and others, such as Kew Royal Botanic Gardens, to try to identify candidate trees for breeding programs. The genomics work has been supported by APHIS and the UK forest research agency, DEFRA. Michigan and Pennsylvania have supported the breeding work. USFS Forest Health Protection has supported work with black and Oregon ash (see below) (J. Koch, USFS, pers. comm.).

Koch has also begun working with Oregon ash, in collaboration with the USFS Dorena Genetic Resource Center (located in Cottage Grove, Oregon) and other partners.

dead hemlock in Massachusetts; photo by Ian Kinahan,
University of Rhode Island

Hemlock woolly adelgid

Scientists are still trying to find the right combination of biocontrol, chemical treatments, and silvicultural manipulation.

For several years, hope has focused on two has been on two predatory beetles, Laricobius nigrinus and L. osakiensis. Scott Salom (Virginia Tech) reports that release of these beetles over the past 20 years has had a significant impact on HWA density and tree photosynthetic rate and growth. However, Laricobius aredifficult to rear and they attack only the sistens generation of the adelgid. Ryan Crandall (University of Massachusetts) reports it has been difficult to establish these beetles in the Northeast. He links this difficulty is caused by temporary drops in HWA populations after cold snaps.

Scientists now agree that need to find predators that attack HWA during other parts of its lifecycle. Hope now focuses on silverflies — Leucotaraxis argenticollis and Le. piniperda. While both species are established in eastern North America, the clades in the east feed almost exclusively on pine bark adelgid, and have not begun attacking HWA. Biocontrol practitioners therefore collect flies in the Pacific Northwest for release in the east. Salom is increasing his lab’s capacity to rear silverflies and exploring release strategies.

Preliminary evidence indicates that the western clades of Leucotaraxis are establishing, although data are not yet definitive (Havill, USFS).

Detecting the presence of biocontrol agents presents several challenges. Tonya Bittner (Cornell) described efforts to use eDNA analysis for this. Some puzzles have persisted; e.g., at some sites, she detected eDNA but caught no silverflies. This raised the question of long eDNA associated with the original release might persist. Another problem is that the assay cannot separate the introduced western L. nigrinus from the native congener, L. rubus (which also does not feed on HWA). She continues efforts to improve this technique.

Others explored interactions of the biocontrol agents with insecticides. Salom is studying the impact of soil-applied insecticides on Laricobius populations, which aestivate in the soil. Preliminary results showed significant reduction in the beetle’s population under soil drench application but not under soil injection. He has not yet analyzed all the data.

Michigan is trying to prevent spread of HWA from five counties along the eastern shore of Lake Michigan (where HWA was introduced on nursery stock) to widespread hemlock forests in northern part of the state. Phil Lewis (APHIS) is studying persistence of systemic insecticides in hemlock tissues, particularly twigs and needles. The pesticides involved are imidacloprid, dinotefuran, and Olefin. He has found that pesticide levels are highest 18 – 22 months after treatment, then decline. They are significantly higher after trunk injection compared to bark spray or soil treatments. Imidacloprid had higher residues in twigs; dinotefuran in needles. This difference affects the likelihood of adelgids actually ingesting the toxin.

healthy hemlock in experimental gap; Jefferson National Forest, VA; photo by Bud Mayfield, USFS

Bud Mayfield (USFS) reported on his study of silvicultural strategies to support healthier hemlocks. While hemlocks normally thrive in shade, it has been determined that sunlight assists small trees reducing HWA sufficiently to counter the tree’s leaf-level stress. Small sapling hemlocks grown in sunlight fix more carbon and convert it to growth in shoots and trunk diameter.

Mayfield found promising immediate suppression of HWA in large gaps in Georgia and Tennessee. By the third year the saplings were still growing, although their faster growth had attracted more HWA. These findings were less clear farther north in central Virginia and western Maryland – Mayfield thinks because HWA pressure there is lower. However, managers must maintain the gaps by cutting rapidly-growing competing woody species. He plans to test this strategy farther north in Pennsylvania. He is still trying to determine the optimal size of the gap.

Posted by Faith Campbell

www.fadingforests.org

FY 23 Funding of Tree Pest Projects

*Phytophthora ramorum*-infected rhododendron plant; photo by Jennifer Parke, Oregon State University

APHIS has released the list of projects funded under §7721 of the Plant Protection Act in Fiscal Year 2023. Projects funded under the Plant Pest and Disease Management and Disaster Prevention Program (PPDMDPP) are intend to strengthen the nation’s infrastructure for pest detection and surveillance, identification, threat mitigation, and safeguard the nursery production system.

APHIS has allocated $62.975 M to fund 322 projects in 48 states, Guam, & Puerto Rico. ~ $13.5 M has been reserved for responding to pest and plant health emergencies throughout the year. USDA is funding ~70% of the more than 460 PPDMDPP proposals submitted.

Funding by Goal Area

1A – Enhance Plant Pest/Disease Analysis $2,057,174
1S – Enhance Plant Pest/Disease Survey $14,375,000
2 – Target Domestic Inspection Activities at Vulnerable Points $6,356,964
3 – Pest Identification and Detection Technology Enhancement $5,295,125
4 – Safeguard Nursery Production $2,079,119
5 – Outreach and Education $4,131,333
6 – Enhance Mitigation Capabilities $13,875,775

By my calculation (subject to error!), the total for projects on forest pests is ~$6.5 M – or a little over 10% of the total. The top recipient was survey and management of sudden oak death: ~$700,000 for research at NORS-DUC and NCSU plus detection efforts in nurseries of 14 states. Other well-funded efforts were surveys for bark beetles and forest pests (projects in 14 states); surveys for Asian defoliators (projects in 14 states); and outreach programs targetting the spotted lanternfly (10 states, plus surveys in California).

Three states (Iowa, Kentucky and Maryland) received funding for surveys targetting thousand cankers disease of walnut; two states (Kentucky and Maine) obtained funding for outreach about the risk associated with firewood. Funding for the Nature Conservancy’s “Don’t Move Firewood” campaign appears under the home state of its leader, Montana.

Massachusetts obtained funding for outreach re: Asian longhorned beetle. Ohio State received funding for developing a risk map for beech leaf disease.

Ten states received funding for no forest pest projects; I don’t know whether they sought funding for this purpose. These states are Arizona, Colorado, Florida, Hawai`i, Idaho, Minnesota, Nebraska, New Mexico, North Dakota, and Puerto Rico. The “National” funding category also contained no forest pest projects.

Looking at the overall funding level might give a somewhat skewed impression because several of the projects with total funding of ~ $500,000 are actually carried out by USDA agencies. These awards are listed under the state in which the USDA facility happens to be located. Nearly half this money ($213,000) goes to a project by an Agriculture Research Service unit in Delaware to study the efficacy of the biocontrol targetting emerald ash borer. Another $105,588 is allocated to detection of the SOD pathogen (Phytophthora ramorum) in irrigation water, undertaken – I think – at the ARS quarantine facility in Frederick, Maryland. A smaller project at a USFS research facility in Connecticut is studying egg diapause in the spotted lanternfly. The Delaware ARS unit is also pursuing biological control of the red-necked longhorn beetle (RNB) Aromia bungi, which attacks primarily stone fruits. Native to China and other countries in Asia, RNB has been intercepted in wood packaging by the U.S. and Europe; it has become established in Italy and Japan [Kim Alan Hoelmer, ARS, pers. comm.] The APHIS lab in Massachusetts is developing a light trap for detection of the Asian spongy moths Lymantria dispar.

I am intrigued that two states (Mississippi and Nevada) are conducting “palm commodity” surveys. Palms are important components of the environment in some states – although I am not certain these are the two most important!

As you might remember, I am also interested in some invaders other than forest pests. Washington has obtained $998,000 to support two projects integral to its efforts to find and eradicate the Asian (or Northern) Giant hornet. Oregon has obtained funding to carry out a survey for these hornets.

Cactus moth larvae feeding on prickly pear cactus; photo by Doug Beckers, via Flickr

I rejoice to see that the Florida Department of Agriculture continues efforts to deploy biocontrol agents targetting the cactus moth. The Agriculture Research Service is evaluating the establishment of biocontrol agents released to counter two highly invasive plants. Re: Brazilian peppertree, I don’t question the damage it has caused in southern Florida but I have grave concerns should the psyllid and thrips reach Hawai`i. I am most distressed to see that Hawaiian Division of Forestry and Wildlife and Department of Agriculture are actively pursuing deliberate introduction of the thrips. ARS is also searching for potential biocontrol agents targetting the invasive cogongrass (Imperata cylindrica). Penn State is working on registering a soil fungus native to North America, Verticillium nonalfalfae, as a biocontrol targetting the highly invasive tree of heaven (Ailanthus).

Phragmites invading Merkle Wildlife Sanctuary, Upper Marlboro, Maryland; photo by Alicia Pimental, (c) Chesapeake Bay Foundation

APHIS is pursuing biocontrol for “Roseau” cane scale. This situation presents a conflict of geographic regions because the plant to be controlled is Phragmites australis. Phragmites is highly invasive in the Mid-Atlantic, Northeast, and Great Lakes states . On the Mississippi delta it is considered important in maintaining wetlands crucial to protecting the Louisiana coast from rising seas.

Finally, USDA is pursuing management tools to contain the Box Tree Moth – a threat to the most widely planted ornamental shrub.

Posted by Faith Campbell

www.fadingforests.org

EAB: Why Quarantines Are Essential

area devastated by EAB; photo by Nathan Siegert, USFS

The emerald ash borer (EAB; Agrilus planipennis) is the most damaging forest insect ever introduced. In late June 2022 it was detected in Forest Grove, Oregon — 26 miles from Portland. This is the first confirmation of EAB on the West Coast – a jump of over 1,000 miles from outbreaks in the Plains states. The infested ash trees were immediately cut down and chipped (see Oregon Department of Agriculture website; full link at end of blog). See my earlier blog on EAB’s threat to ash-dominated riparian wetlands in Oregon.

ash-dominated swamp along the Willamette River in Oregon; photo by William Wyatt, ODF

Oregon has been preparing for the EAB:

The state finalized its response plan in March 2021; see reference at end of blog.
The state sought and received funds from USDA APHIS to initiate a biocontrol program. The funds were not from APHIS’ operational budget, but from the agency’s Plant Pest and Disease Management and Disaster Prevention Program (PPDMDPP) (Farm Bill money).
State and federal agencies have begun collecting seeds for resistance screening and a possible breeding program.

EAB: Why Quarantines Are Essential

As you might remember, in January 2021 APHIS dropped its federal regulations aimed at curtailing EAB’s spread via movement of wood and nursery plants. This shifted the responsibility for quarantines to state authorities. Instead, APHIS reallocated its funding to biological control. I raised objections at the time, saying the latter was no substitute for the former.

A new academic study shows that APHIS’ action was a costly mistake.

Hudgins et al. (2022; full citation at end of this blog) estimate EAB damage to street trees alone – not counting other urban trees – in the United States will be roughly $900 million over the next 30 years. These costs cannot be avoided. Cities cannot allow trees killed by EAB to remain standing, threatening to cause injury or damage when they fall.

ash fallen onto house in Ann Arbor, Michigan; photo courtesy of former mayor John Hieftje

The authors evaluated various control options for minimizing the number of ash street trees exposed to EAB. They assessed the trees’ exposure in the next 40 years, based on management actions taken in the next 30 years.

In their evaluation of management options, Hudgins et al. tried to account for the fact that the effect of management at any specific site depends on the effects of previous management. Additional complexity comes from the facts that the EAB is spread over long distances largely by human actions (i.e., movement of infested wood); and that biocontrol organisms also disperse.

They conclude that efforts to control spread at the invasion’s leading edge alone – as APHIS’ program did – are less useful than accounting for urban centers’ role in long-distance pest dispersal via human movement. Cities with infested trees are hubs for pest transport along roads. Hudgins et al. say that quarantine programs need to incorporate this factor.

Hudgins et al. concluded that the best management strategy always relied on site-specific quarantines aimed at slowing the EAB spread rate. This optimized strategy, compared to conventional approaches, could potentially save $585 million and protect an additional 1 million street trees over the next 40 years. They also found that budgets should be allocated as follows: 74-89% of funds going to quarantine, the remaining 11% to 26% to biocontrol.

In other words, a coherent harmonized quarantine program – either through reinstatement of the federal quarantine or coordination of state quarantines — could save American cities up to $1 billion and protect 1 million trees over several decades. Since street trees make up only a small fraction of all urban trees, up to 100 million urban ash trees could be protected, leading to even greater cost savings.

Unfortunately, such a coordinated approach seems unlikely. States continue to have very different attitudes about the risk. For example, Washington has no plans to adopt EAB regulations, despite it being detected in Oregon. To the north, Canada already has EAB quarantines and Hudgins et al. advise that they be maintained.

The authors recognize that quarantines’ efficacy is a matter of debate. Quarantines require high degrees of compliance from all economic agents in the quarantine area. Also they need significant enforcement effort. Some argue that meeting either requirement, let alone both, is unrealistic. However, under Hudgins et al.’s model, use of quarantines was always part of the optimal management method across a variety of quarantine efficiency scenarios. Again, these models point to allocating about 75% of the total budget to quarantine implementation. In all scenarios, reliance solely on biocontrol led to huge losses of trees compared to a combined strategy.

Hudgins et al. asked their model for optimal application of both quarantines and biocontrol agents. For example, quarantine enforcement could focus on limiting entry of EAB at sites that: 1) have many ash street trees, 2) currently have low EAB propagule pressure, but 3) are vulnerable to receiving high propagule influx from many sites. Seattle is a prime example of such a vulnerable city with many transportation links to distant cities with significant ash populations.

On the other hand, quarantine enforcement could strive to limit outward spread (emigration) of EAB from which high numbers of pests could be transported to multiple other locales, each with many street trees and low propagule pressure. These sites would be along the leading edge of the invasion and where the probability of long-distance pest dispersal is high.

Authorities should be prepared to adjust quarantine actions in response to changing rates and patterns of invasion spread.

Biocontrol agents should be deployed to sites with sufficient EAB density to support the parasitoids, especially sites predicted to be hubs of spread.

Hudgins et al. concede that they did not explicitly account for:

1) The impact of uncertainty regarding EAB spread on the model;

2) Alternative objectives that might point to other approaches, e.g., minimizing extent of invaded range, or reducing the number of urban and forest trees exposed to EAB;

3) Impacts of predators, such as woodpeckers, on EAB populations;

4) Synergistic impacts from climate change, which by exacerbating stress on ash trees will probably increase tree mortality from EAB infestations; and

5) Variation in management efficiency depending on communities’ capacities.

In the future, Hudgins et al. hope to test their model on other species to determine whether there is a predictable spatial pattern for all wood boring pests, that is, should quarantines always be focused on centers of high pest densities as probable sources of spread. Determining any patterns would greatly assist risk assessment and proactive planning.

dead ash near major road in northern Virginia; photo by F.T. Campbell

In an earlier study, Dr. Hudgins and other colleagues projected that by 2050, 1.4 million street trees in urban areas and communities of the United States will be killed by introduced insect pests – primarily EAB. This represents 2.1- 2.5% of all urban street trees. Nearly all of this mortality will occur in a quarter of the 30,000 communities evaluated. They predict that 6,747 communities not yet affected by the EAB will suffer the highest losses between now and 2060. However, they evaluated risks more broadly: the potential pest threat to 48 tree genera. Their model indicated that if a new woodboring insect pest is introduced, and that pest attacks maples or oaks, 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 via a port in the South. I have blogged often about the rising rate of shipments coming directly from Asia to the American South

SOURCES

Hudgins, E.J., J.O. Hanson, C.J.K. MacQuarrie, D. Yemshanov, C.M. Baker, I. Chadès, M. Holden, E. McDonald-Madden, J.R. Bennett. 2022. Optimal emerald ash borer (Agrilus planipennis) control across the U.S. preprint available here: https://doi.org/10.21203/rs.3.rs-1998687/v2

Hudgins, E.J., F.H. Koch, M.J. Ambrose, B. Leung. 2022. Hotspots of pest-induced US urban tree death, 2020–2050. Journal of Applied Ecology

Members of this team published an article earlier that evaluated the threat from introduced woodborers as a group to U.S. urban areas; see E.J. Hudgins, F.H. Koch, M.J. Ambrose, B. Leung. 2022. Hotspots of pest-induced US urban tree death, 2020–2050. Journal of Applied Ecology

Oregon Department of Agriculture: https://www.oregon.gov/oda/programs/IPPM/SurveyTreatment/Pages/EmeraldAshBorer.aspx

Posted by Faith Campbell