elm zigzag sawfly larvae feeding on an elm leaf; photo by Delaney Serpan
As one of the newest – and most unique – invasive insects, elm zigzag sawfly (EZS; Aproceros leucopoda) has been making headlines across the eastern U.S. and Canada since 2020. The defoliating pest was first confirmed in North America in Québec, Canada and has since spread rapidly across many states and provinces. As its name suggests, EZS larvae feed primarily on elm in a distinctive zigzag pattern. Moving inwards from the leaf edge, the larvae can eventually consume nearly the entire leaf, leaving nothing but the midrib and a few lateral veins behind. Defoliation from EZS can range from nearly undetectable to 100% canopy defoliation of a mature tree.
EZS is a multivoltine insect, meaning it can have multiple generations in a single growing season. In Europe, where EZS has been invasive since 2003, 1 to 4 generations are common though up to 6 generations have been recorded. In the U.S., many regions document up to 5 generations per year.
In the early spring, EZS emerges from the soil where it has overwintered. They reproduce parthenogenetically- a form of asexual reproduction- allowing them to lay eggs immediately following adult emergence. Each individual is able to lay up to 49 eggs, drastically increasing EZS reproductive potential. Once the eggs hatch, the larvae begin feeding on the foliage until they are ready to pupate. At that point, the larva may build a summer cocoon, attached to a nearby object such as a branch or fence post. Four to 7 days later, an adult will emerge. The entire life cycle only takes 3 to 6 weeks. Alternatively, the larva could drop to the soil beneath the tree’s canopy where it will build its winter cocoon and overwinter, waiting to repeat the cycle the following spring. A small portion of each generation create overwintering cocoons.
EZS summer cocoons attached to the underside of a leaf with evidence of larval feeding; photo by Delaney Serpan
Where is EZS now?
As of the end of 2025, EZS can be found in 15 states and 4 provinces as far west as Minnesota and Manitoba and as far south as North Carolina and Tennessee.
map of states/provinces with official EZS detections;
Invasion pathways in North America are currently unknown; however, EZS has been documented attaching its summer cocoons to truck wheel wells and other objects which may be moved. The subsequent movement of these objects can potentially contribute to EZS spread. It has also been suggested that infested elm nursery stock or potted soil of any plants could be a potential pathway for EZS, but more research is needed to fully understand this.
EZS cocoons on truck – under side mirror & wheel well; photos by Jared Beach, adapted from Oten et al. 2025
How does EZS affect the trees?
Defoliating pests typically decrease the aesthetic value of trees but leave the host largely unharmed. Across Europe and its native range of eastern Asia, EZS defoliation is relatively minimal, with the occasional severe outbreak resulting in total defoliation of a tree. Resulting branch dieback is even more uncommon.
When EZS was first found in North America, particularly North Carolina and Virginia, there were initial concerns about the implications of a warmer climate accelerating development. Like most insects, EZS development is related to temperature; a warmer climate allows for faster insect development. It was hypothesized that a longer growing season could allow for faster population growth and potentially more damage to host trees. At this point, it is still unclear if this will consistently occur in the southern extent of the range. In North Carolina, reported damage has varied widely since it was found there in 2023. Some trees have been 75% defoliated or more multiple years in a row and are exhibiting upwards of 20% branch dieback after just 3 years. However, trees with less than 10% defoliation and no branch dieback have also been recorded.
Since its first detection in North America, researchers have been working to better understand how this pest will affect stakeholders. They’ve been conducting research on the phenology and voltinism of EZS, exploring novel host associations, and evaluating management techniques. Here’s what they’ve learned so far.
A severely defoliated American elm in Surry County, N.C. Photo by Delaney Serpan
First, the bad news.
Elm zigzag sawfly has recently been found to feed on Japanese zelkova (Zelkova serrata), another common ornamental planting within the Ulmaceae family. However, it is important to note that Japanese zelkova is likely not a preferred host. It is suggested that while EZS can complete its life cycle on Japanese zelkova, it will do so only when no other suitable host is present. Researchers are continuing to explore this novel host association.
But help is on the way! There are management recommendations to control elm zigzag sawfly.
Research conducted at North Carolina State University has determined that soil injections of imidacloprid or dinotefuran at label rate are effective methods to significantly reduce larval populations on infested trees. Both active ingredients are easily accessible to landowners and can provide at least one year of protection against EZS. There is ongoing research to explore more treatment options, including augmentative biocontrol.
What can you do about elm zigzag sawfly?
If you are in an EZS-infested region, check vehicles or outdoor items before moving them.
And if you find EZS, report it! To best manage and prevent the spread of EZS, forest health professionals need to know where it is. Elm zigzag sawfly is the only insect that feeds in the unique zigzag pattern on elm trees. If you see the diagnostic feeding pattern, take a picture of it and contact your county’s local Extension agent or state forestry agency to report it.
Invited blog posted by Delaney Serpan
Delaney Serpan is a second-year Ph.D. student in the Forest Health Lab at NC State University, where she studies elm zigzag sawfly biology and management. She first began working with elm zigzag sawfly as an undergraduate researcher shortly after it was detected in North Carolina for the first time. Working with a novel invasive species on the leading edge of its invasion has been incredibly rewarding. Her work aims to provide accessible management techniques to stakeholders while also protecting elms, an already imperiled species, from further damage.
CISP welcomes comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
Kevin Saville reports for the Journal of Commerce that containerized imports in 2025 are expected to be only 25.2 million TEUs, a decrease of 1.4% from 2024.
Declines are particularly large in the final months of 2025 since importers frontloaded their purchases to try to get ahead of the Trump Administration’s new tariffs. Imports for the first half of the year were up 3.6% compared with 2024 at 12.53 million TEUs. Thus, Saville’s sources expect November import levels to be 11.6% lower than in November 2024; December’s to be almost 13% lower.
Analysts expect the steeper decline to continue into the new year. Ben Hackett, of Hackett Associates, expects import volumes in the first four months of 2026 to be 10.3%, 8.5%, 16.8% , and 11% lower than the corresponding months a year earlier. The data source covers the ports of Los Angeles/Long Beach, Oakland, & Seattle & Tacoma on the West Coast; New York/New Jersey, the Port of Virginia, Charleston, Savannah, Port Everglades, Miami & Jacksonville on the East Coast; & Houston on the Gulf Coast. These are not all the maritime ports, but they are the major ones.
Another JOC reporter, Michael Angell, quoted several sources as saying they expect import volumes for all of 2026 to be flat or down 2% from 2025. Illustrating the reversal from past trends, The Port Authority of New York and New Jersey expects total container volumes in 2026 to be 8.5 million TEUs, a decline of about 2% from 2024. Since 2016, NY-NJ port container volumes have grown at an annual average of 4.2%.
As I have blogged before — see here and here — these swings in import volumes threaten to undermine programs intended to prevent introductions of wood-boring insects hitching rides in wood packaging material. While the higher volumes arriving from Asia in the first half of 2025 pose the most obvious risk, falling volumes reduce fee-based funding that support port inspectors. Another factor is the shift to suppliers other than China – primarily countries in Southeast Asia. Two beneficiaries of this shift are Vietnam and – at least initially – India. They have much better records of compliance with ISPM#15-mandated treatments for wood packaging link than does China.
A third JOC source reports that while US and European imports are down, trade volumes in Asia, Africa, the Middle East and Latin America are rising. I expect this growing trade to facilitate new pest introductions, although we will have to wait several years to see any data.
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
pine plantation near Buenos Aires; photo by Biologicadero via Wikimedia
I have learned about the introduction of a North American woodwasp, Sirex obesus, in Brazil. Forestry interests in South America are worried that this woodwasp will cause significant damage to the pine plantations occupying 4.6 million hectares on the continent.
In July 2023, experts at the Estação Experimental de Ciências Florestais at ESALQ/USP in Itatinga, São Paulo, Brazil, investigated dead and symptomatic trees of several Pinus species and subspecies. They expected the causal agent to be Sirex noctilio – a woodwasp native to Europe and North Africa that has caused considerable damage to South American pine plantations since the 1980s (Wilcken et al.).
However, the pine species attacked were not typical hosts for S. noctilio (in Brazil, loblolly pine Pinus taeda). Instead, the infected trees were Caribbean pines, i.e., Pinus caribaea hondurensis, P. caribaea bahamensis, P. caribaea caribaea, P. maximinoi, P. tecunumani. The responsible woodwasp was identified as Sirex obesus. This species is native to the southwestern United States and northern and central Mexico (Wilcken et al.). This species is closely related to S. californicus (Wilcken et al.).
A second outbreak was found in November ~ 130 km away (still in São Paulo state). Scientists have not determined whether the two São Paulo outbreaks are related. Dr. Villacide reports (pers. comm.) that the two populations genetics have been compared, but he does not have the results.
A third population has been detected in a second, neighboring, state, Minas Gerais (Wilcken to Lantschner and Villacide).
Dr. Villacide (pers. comm.) reports that Brazilian scientists are trying to delimit the extent of the outbreaks. Public and private scientists in other countries with pine plantations have begun developing responses.
This is the first record of S. obesus outside of North America (Wilckens et al.).
Little is known yet about this woodwasp’s probable impact. It is clear that it can oviposit in a wide range of pines. In its native range, S. obesus has been reported on three host species: Pinus ponderosa, P. teocote (twisted-leaf pine), and P. leiophylla (no common name; native to Chihuahua – mostly in Mexico, and border areas of New Mexico and Arizona]. In Brazil, as noted, it has been recorded on other species as well as the hybrids P. caribaea x P. elliottii and P. caribaea x P. tecunumanii (Wilcken et al.).
So for purposes of their risk assessment, Lantschner and Villacide assumed that S. obesus can affect any of the species commonly planted in the region: P. taeda, P. elliottii, P. ponderosa, P. contorta, P. caribaea, P. oocarpa, P. patula, P. radiata, and P. tecunumanii (Lantschner and Villacide).
The risk assessment predicts suitable climatic conditions for invasion by S. obesus in 48% of the areas where South American pine plantation occur, particularly in montane and high-altitude regions along the Andean corridor and central-eastern Brazil. Incorporating other factors – host distribution, proximity to invaded areas, and volume of wood imports from Brazil – identified the most vulnerable areas as in southern Brazil, northeast Argentina, the Argentine Patagonia, and central Chile (Lantschner and Villacide).
pine plantation in Argentina; photo by Tomas Asurmendi via pexels
Preliminary sampling (Wilcken et al.) indicates the impacts could be severe. Mortality varies by species: in the worst cases average mortality approached 43% on P. caribaea hondurensis but only 11% on loblolly pine (P. taeda). They expect mortality rates to increase. Another 30% of P.c. hondurensis trees are dripping resin, a sign of woodwasp oviposition. If these eggs hatch, those larvae will probably kill the affected trees. Such a result would increase total mortality of P.c. hondurensis from 43% to ~ 73%. For P. taeda, the current mortality rate of 11% could rise to 49% as an additional 38% of trees succumb. Following this logic, these areas could experience complete tree mortality within a few years. Given the extent of pine plantations, and possible mortality rates, even a partial spread of S. obesus could lead to significant econ losses.
As second factor is the number of generations per year; the higher the number, the faster woodwasp populations can increase. Wilckens et al. report that adult emergence in Pinus logs maintained in cages indicates that S. obesus could have two or three generations per year.
S. obesus seems to prefer a different climate than S. noctilio. As noted, S. obesus seems to prefer montane and high-altitude climates. S. noctilio is concentrated in lowland temperate and humid regions (Lantschner and Villacide). The newly introduced species might substantially broaden the geographic area where pine plantations might be at risk – although further research is needed to clarify this point.
S. obesus also appears to be spreading at a rapid rate — ~46 km / year. At this rate, Lantschner and Villacide say it could spread throughout all major pine plantation areas in Brazil in less than years.
Sirex woodwasps kill trees by injecting a symbiotic wood decay fungus and a phytotoxic mucus into the tree when ovipositing. The toxin weakens the tree, allowing the fungus to spread, typically killing the tree in as little as three–four months. In North America S. obesus is associated with Amylostereum chailletti. While this species has not yet been confirmed in Brazil, (Wilckens et al.). Brazilian scientists are exploring whether S. obesus might adopt the fungus already present, Amylostereum areolatum, which is associated with S. noctilio.
Two insect species known to feed on woodwasps have emerged from logs infested with S. obesus: Ibalia leucospoides (Hymenoptera: Ibaliidae) and a species of Schlettererius (Hymenoptera: Stephanidae). While these two predators have not proved to be effective controls of woodwasps by themselves, they might become part of a control program. The parasitic nematode, Deladenus siricidicola (Nematoda: Neotylenchidae) used successfully in several South Hemisphere countries to control S. noctilio has not been found in Brazil (Wilckens et al.).
Scientists don’t know the pathway by which S. obesus entered Brazil. Wilckens believes it was via wood packaging; technicians from the Ministry of Agriculture have found some pallets associated with imports that lacked the ISPM#15 mark (Wilckens et al.).
Both Lantschner and Villacide and Wilcken et al. stress the vulnerability of South American pine plantations to introduction of damaging pests. The plantations are reportedly intensively managed, even-aged, regularly spaced monocultures. These conditions can facilitate invasive species establishment and spread by providing abundant host resources and reduced natural enemy pressure. Lantschner and Villacide cite Michael Wingfield that in plantation forestry, introduction of a single pest species can damage large areas of valuable timber.
mortality caused by Sirex noctilio in a pine plantation in Argentina; photo courtesy of Jose Villacide
The family Siricidae contains more than 120 species distributed across the forests of the Northern Hemisphere. In their native ranges they are typically minor or secondary pests (Wilckens et al.). Woodwasps have demonstrated that they can be transported in international commerce – S. noctilio alone has invaded pine stands (native or exotic) in nine countries in Oceania, Africa, and South and North America. Three other species in the family — Urocerus gigas, Urocerus flavicornis and Tremex fuscicornis – have been detected in South America (Wilckens et al.). If each represents a unique threat, countries with widespread pine plantations should enhance their phytosanitary programs. Exporting parties, e.g., the United States and European Union, should assist in efforts to prevent spread of these wood borers. One major step would be to strengthen regulations governing wood packaging material. [To see my criticisms of shortfalls of the ISPM#15 system, scroll down the list of blogs to “Categories” and click on “wood packaging”.]
Lantschner and Villacide cautionthat their assessment is based on a limited record of S. obesus occurrences in its native range. This range might be restricted by factors other than climate, including geographic barriers or biotic interactions (natural enemy pressure or interspecific competition). If so, the species’ potential invasive range might be larger than the climate-based models predict.
Recommendations for management strategies
I applaud Lantschner and Villacide for proposing immediate steps to improve management of the threat posed by introduction of S. obesus. These recommendations should prioritize enhanced phytosanitary inspections of wood products moving between high-risk regions and other South American countries. They suggest that Brazil adopt bilateral agreements with its major trading partners which would specify protocols for woodwaspdetection and quarantines. [Since many of these countries already have established populations of S. noctilio they probably do not have strong phytosanitary measures targeting wood borers at present.] Lantschner and Villacide advise creation of targeted surveillance programs in southern Brazil, northeastern Argentina, Argentine Patagonia, and central Chile. They should focus on sites near major transportation hubs and border crossings. Less intense surveillance should be instituted in regions they classified as medium risk. Again, the focus should be on major points of entry for imported goods and on plantations located near the Brazilian border. They note that preventing spread of S. obesus into new areas will require not only national efforts but also regionally coordinated monitoring, research, and forest health policies.
Lantschner and Villacide also identify priority areas for future research. These include clarifying S. obesus’shost range, the environmental conditions that enable the woodwasp to establish and persist beyond its native range, dispersal rates, and whether S. obesus exhibits pulse-like pop dynamics[long periods of low density interrupted by sudden outbreaks] seen in S. noctilio.
Dr. Villacide (pers. comm.) reports that Brazilian scientists are trying to delimit the extent of the outbreaks. Public and private scientists in other countries with pine plantations have begun developing responses. Dr. Villacide has posted a video from a recent online seminar sponsored by the Southern Cone Forest Health Group. Go to https://youtu.be/uVU6CpFNhlQ?si=lqXtwJTtz5rKXfL3 or https://sanidadforestalconosur.org/
A wider prespective
Dr. Villacide’s attention to Sirex obesus is part of his broader work on pest issues in South America’s commercial plantations. In another publication (Villacide and Fuetealba 2025; full citation at the end of this blog), he explores how to make these plantations sustainable in the face of rising threats from pests – both introduced and native to the region. Dr. Villacide and Alvaro Fuetealba report that every year 1.2 million hectares of plantations in the Southern Cone are affected by pests. Their vulnerability of will be worsened by the extreme weather events expected under climate change.
These plantations present vast areas of homogeneous stands: ~97% of the Southern Cone planted area consists of exotic tree species – mainly Pinus and Eucalyptus. Typical plantations are high density and managed intensively – including thinning, pruning, and fertilizing – to prompt rapid growth. As Villacide and Fuetealba point out, while these practices maximize wood production efficiency, they also lead to biological homogenization and reduced resilience to pests.
They report that pine plantations are under attack by wood and bark borers that have followed pines to the region, including Sirex noctilio, Orthotomicus erosus, and Cyrtogenius luteus; and now the newly detected Sirex obesus (above). At least two fungal pathogens — Fusarium circinatum and Dothistroma septosporum – have also been introduced. The principal threat to pine plantations from native pests comes from leaf-cutting ants (Atta and Acromyrmex).Eucalyptus plantations are plagued by several insects that have arrived from Australia, including Phoracantha semipunctata, Thaumastocoris peregrinus, and Leptocybe invasa. Pests native to the region that attack Eucalyptus are the Chilean carpenter worm (Chilecomadia valdiviana) and the leaf-cutting ants.
Cordilleran cypress; photo by LBM 1948 via Wikimedia
Threat to native conifer
More worrying to me is that introduced pests have entered native forests. Villacide and Fuetealba report that the aphid Cinara cupressi is attacking the native conifer Austrocedrus chilensis. Cordilleran cypress, also called Chilean or Patagonian cedar, is an endemic, monospecific tree in the Cupressaceae family. In southern Argentina and Chile the species forms pure and mixed stands with southern hemisphere beech (Nothofagus spp.) across ~ 160,000 ha. The profile Cinara cupressi on the Global Invasive Species Database is unclear about how many species are in the species complex and their places of origin.
Cordilleran cypress is also under attack by the oomycete Phytophthora austrocedri, an oomycete of unknown origin. This pathogen is of unknown origin. It is now thought to have been present in Argentina since at least the 1960s. P. austrocedri has also been ntroduced to Europe, western Asia, and North America.
Villacide and Fuetealba advocate several actions to might diversify tree species in the plantations to reduce their vulnerability to pests. They note that this recommendation builds on foundational ecological theory, including the resource concentration and natural enemy hypotheses. Diversity-promoting actions should reach beyond any plantation to the landscape level. Managers should consider connectivity of susceptible stands, the number of nutritionally optimal host trees in the landscape, and the availability and quality of hosts in adjacent stands.
Villacide and Fuetealba say mixed plantations can provide additional ecological and economic benefits, such as enhanced stand-level productivity; production of a wider range of commercial and subsistence products; and greater resistance and resilience to natural disturbances, e.g., extreme weather events.
They warn that designing and implementing mixed plantations must reflect ecological interactions and pest dynamics as well as management. There is need for regionally coordinated experimental plantations where scientist could test how variables such as tree species composition, density and spatial arrangement, and silvicultural practices influence pest dynamics, forest productivity, and ecosystem resilience under local conditions. They suggest incorporating sentinel plantings both early-warning systems and decision-support tools at plot and regional scales. Researchers should evaluate pest-specific responses, productivity trade-offs, long-term forest health outcomes under different scenarios.
Since the plantations extend across a multinational region with few natural barriers and uniform silvicultural practices, as well as high levels of trade, so do the pest problems. Therefore, the response must also be regional – e.g., regional experimental plantations and living laboratories. A collaborative approach linking researchers, forest managers, and policymakers is essential to translate experimental findings into practice and develop adaptive, ecol grounded silvicultural strategies. Long-term ecological trials must be embedded in operational contexts and aligned across countries.
SOURCES
Lantschner, V. and J. Villacide. 2025. Invasion Potential of the Recently Established Woodwasp Sirex obesus. Neotropical Entomology. (2025) 54:117 https://doi.org/10.1007/s13744-025-01347-6
Villacide, J. and A. Fuetealba. 2025. Pests in plantations: Challenging traditional productive paradigms in the Southern Cone of America. Forest Ecology and Management 597 (2025) 123127
Wilcken, C.F., T.A. da Mota, C.H. de Oliveir, V.R. de Carvalho, L.A. Benso, J.A. Gabia, S.R.S. Wilcken, E.L. Furtado, N.M. Schiff, M.B. de Camargo, M.F. Ribeiro. 2025. Sirex obesus (Hymenoptera: Siricidae) as invasive pest in pine plantations in Brazil. Scientific Reports. 2025. 15:22522 https://doi.org/10.1038/541598-025-06418-7
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
Japanese knotweed (Reynoutria japonica) – one of the worst invaders around globe. Photo by Will Parson, Chesapeake Bay Program via Flickr
On 23 October, Science published a five-page, data-packed analysis of bioinvasion impacts on terrestrial ecosystems!!!
Thakur, Gu, van Kleunen, and Zhou (full citation at end of this blog) analyzed 775 studies with the goal of improving understanding of factors contributing to invasions’ impacts – as distinct from “invasibility” (ability to establish). This knowledge is essential to assessing the risk posed by introduced species and setting priorities for management. They analyzed five ecological contexts—diversity of native species and introduced species in the recipient systems, latitude, invader residence time, and invader traits.
They concluded that ecological factors commonly used to explain invasion success do not consistently translate into strong predictors of invasion impacts. Impacts vary in response to the context of the invasion.
[In January 2026, the authors announced changes in details of the article due to some errors in the database and their understanding of it. (Science 8 Jan 2026 Vol. 391 Issue 6781) They conclude that the corrected analysis did not alter the trends described or the overall conclusions.]
limber pine (Pinus flexilis) – one of the species killed by Cronartium ribicoli; photo by F.T. Campbell
Among the studies available for analysis, reports on plants dominated: 605 focused on plant invasions, 114 on animal invasions, and only 56 on microbial invasions. Among the animals were one study of Adelges tsugae(hemlock woolly adelgid), two studies of Agrilus planipennis(emerald ash borer) and one study each of Lymantria dispar (spongy moth), and Ips pini (North American pine engraver). Studies also addressed earthworms, ants, rats, and feral hogs. Microorganisms included Cronartium ribicoli (white pine blister rust) and several Phytophthora species, including P. agathidicida(kauri dieback), P. alni (affects alders),and P. ramorum (sudden oak death).
Thakur et al. note the skewed taxonomic coverage and say that the low number and narrow taxonomic/ecological variety in the animals and microorganisms probably limit their ability to reach robust conclusions about the impacts of such invasions.
The most consistent negative impact they found is reductions in native plant diversity. While this is not surprising given the studies analyzed, I think it is still important since it counters the widespread sense that plant invasions are somehow less deserving of a robust response.
The authors also detected some broader ecosystem impacts of plant invasions. Plant invasions increased soil organic carbon; soil nitrogen (ammonium and nitrate), and available phosphorus; soil moisture, litter biomass; and emissions of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). The changes in biogeochemical properties might reinforce impacts on native plant communities. The reported increase in greenhouse gas emissions might reflect a bias in the studies so Thakur et al. call for more research to solidify this finding.
High native plant species richness had only a weak overall effect on ecosystem-level impacts. While plant invasions often resulted in higher overall plant species richness, when considering only native community responses, the gain in species numbers did not necessarily indicate conservation benefits. Native plants’ biomass increased after invasion. This might reflect short-term increases in productivity in response to altered resource conditions or structural facilitation, rather than a long-term reversal of competitive exclusion. Finally, the longer the invasive [plant] species had been present, the greater the negative effects on native diversity. However, soil abiotic property impacts weakened over time. In fact, the initial increase in soil organic carbon and total nitrogen disappeared after 6 to 10 years. This development might reflect fertilization of ecosystems by long-established nitrogen-fixing invaders such as non-native legumes.
Traits of non-native plant species related to growth and resource acquisition were overall weak predictors of ecosystem impacts. Thakur et al. consider that this finding reflects the relatively narrow range of specific leaf area exhibited by the plant species studied most commonly.
Consequently, Thakur et al. urge managers to focus on containment and impact mitigation, and to prioritize persistent losses of native plant diversity. When considering abiotic responses that might lessen over time, managers should apply “adaptive monitoring” (which is not defined).
Thakur et al. had greater difficulty determining the impacts of animal and microorganism invasions because of the smaller number of studies. They could not determine the effect of native species richness. The observed decline in soil organic carbon they thought was attributable to the large proportion of studies (9 out of 114) that focused on introduced earthworms. Earthworms reduce organic matter by consuming litter. Mammals were also found to reduce soil organic carbon. Introduced insects had no significant ecosystem effects on soil organic carbon. Non-native animals also increased soil emissions of carbon dioxide and nitrous oxide. The microorganisms included in reviewed studies decreased soil ammonium and increased nitrate, consistent with elevated nitrification. While data on body size of invasive animals were sparse, the authors could determine that larger-bodied species tended to increase soil nitrate while reducing effects on total soil N.
Applying the Results
Thakur et al. report that residence time outperformed other factors as a predictor of invasion impacts. The authors regret the scarcity of long-term studies, especially in the Global South, that could increase our understanding of whether these impacts persist or shift under sustained invasion pressure.
How can scientists apply this information in risk assessments evaluating not-yet introduced species or in deciding what is the appropriate intensity of immediate response to newly detected incursions. Should they give greater weight to others’ studies that focus on long-established invasions by the species in question? Otherwise, this finding seems to largely duplicate the long-established “invasion curve”.
I hope scientists will note that observational studies generally showed stronger impacts than experimental ones, particularly in the case of plant invasions. Perhaps this is true because observational studies better incorporate environmental heterogeneity and longer time spans.
Agrostis stolonifera – one of the plants invading on Prince Edward Island, an Antarctic region island under South African jurisdiction. Photo by Stefan Iefnaer via Wikimedia
Thakur et al. note that one factor they analyzed, “latitude”, incorporates several ecological and anthropogenic components relevant to invasion impacts. One element is the greater native bioidiversity in warmer, lower-latitude, regions. According to the “biotic resistance” hypothesis, greater diversity might make these systems more resistant to bioinvasion. However, the situation is complicated by the fact that temperate regions have also often experienced longstanding and intensive land-use modifications — which are believed to facilitate invasive species establishment and spread. I regret that the authors make no attempt to separate the effects of factors that are anthropogenic from those arising from immutable conditions, e.g., latitude, topography, weather patterns, etc.
Thakur et al. call for more studies that cover a wider geographic range. In addition, the studies should include more experimental designs and explore the relationship between invaders’ traits and impacts — especially regarding animals and microbes.
SOURCE
Thakur, M.P., Z. Gu, M. van Kleunen, X. Zhou. 2025. Invasion impacts in terrestrial ecosystems: Global patterns and predictors. Science 23 October 2025
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
ohia trees killed by ROD near Pahoa, Hawai`i; with JB Friday; photo by F.T Campbell … APHIS has not applied NAPPRA to this pathogen
As I have documented numerous times in these blogs, [see here, here, here, here, here, here, here and here] forests throughout the world are being reshaped by rising numbers of introduced, non-native pathogens. Once established, these diseases are nearly impossible to contain, much less eradicate.
While the worst effect of such bioinvasions is widespread mortality of host species, even “lesser” results produce significant changes in the impacted ecosystems.
I believe that the international phytosanitary “system” adopted by the World Trade Organization (WTO) and amended by the International Plant Protection Convention (IPPC) in the mid-1990s impedes efforts to prevent introductions of pathogens. These rules require unattainable levels of certainty about an organism’s impacts before it can be restricted. Scientists such as Haoran Wu and Kenneth Raffa have called for phytosanitary approaches that will be more effective because they are realistic, reflect the true level of threat, and the limits of current science. I agree and have repeated their calls.
How Well Is This “System” Keeping Pathogens At Bay?
If the world’s phytosanitary system worked well, we should be seeing fewer high-risk forest pathogens being introduced to new countries. Instead, examples abound of pests invading new ecosystems in the post-WTO/IPPC era: Austropuccinia psdii — detected in Hawai`i in 2005, Japan in 2009, Australia in 2010, China in 2011, New Caledonia and South Africa in 2013, Indonesia and Singapore in 2016, and New Zealand in 2017.
Phytophthora ramorum – 8 to 14 additional introductions to California after its initial detection.
Fusarium disease vectored by beetles in the Euwallaceae genus:
Euwallacea fornicatus s.s.— detected in southern California in 2003, Hawai`i in 2007, Israel in 2009, in South Africa in 2012, in Australia in 2021, and in Argentina and Uruguay in 2023 and 2024 . The haplotype detected in South America and several European greenhouses differs from that established elsewhere.
E. kuroshio detected in southern California in 2013; has spread to nearby Mexico
E. interjectus detected in central California in 2024.
Boxwood blight fungus Calonectria pseudonaviculata — first detected in the Caucuses in 2010 and the US in 2011. Now established in at least 24 countries in three geographic areas: Europe and western Asia; New Zealand; and North America. Boxwood blight has caused rapid and intensive defoliation of native stands of Buxus sempervirens. Although disease was detected in United Kingdom in the mid-1990s, the causal agent was not determined until 2002.
Beech leaf disease caused by the nematode Litylenchus crenatae subsp. mccannii — detected near Cleveland, Ohio, in 2012. Has since spread east to the Atlantic Ocean, south to Virginia, north into Ottawa.
Phytophthora austrocedrii — detected in nurseries in Ohio and Oregon in 2024. Previously known from Argentina and in England and Scotland. At the latter location it is causing mortality of native Juniperus and introduced Cupressaceae. See here and here.
Most of these pathogens were unknown at the time they were discovered – because they were causing disease in the invaded ecosystems.
beech leaf disease symptoms in northern Virginia; photo by F.T. Campbell
In the Face of International Failures, How Can USDA’s APHIS Succeed?
When countries choose to prioritize preventing bioinvasions, they can impose more restrictive controls than those implemented by the WTO/IPPC system.
I urge USDA to more proactively use its authority to protect America’s plant resources. In particular, I urge USDA leaders to use the NAPPRA authority more effectively and quickly. This allows the agency to temporarily prohibit importation of plants that host potentially damaging pathogens. ). https://www.aphis.usda.gov/plant-imports/nappra
We Americans can’t protect our forests from pathogens without APHIS responding more promptly to recent detections of pathogens in North America and on Pacific islands. Recent events are not encouraging.
The agency did undertake an analysis of Phytophthora austrocedrii after it was detected in nurseries in two states. Unfortunately, in my view, APHIS and the states decided the pathogen was too widespread so they dropped any idea of regulating it. This was despite the apparent threat to junipers across the country. See here and here. P. austrocedri also attacks cypress trees, including Port-Orford cedar, Chamaecyparis lawsoniana. USFS scientists recently announced success in breeding POC trees resistant to a different pathogen.
There are no indications that APHIS will respond to detection of a new pathogen causing wilt disease in elms (Plenodomus tracheiphilus) recently discovered in Alberta, Canada. The pathogen is spread primarily through movement of infected plant material, including on asymptomatic material. Current U.S. regulations do not prohibit importation of plants or cut greenery in the Ulmus genus from Canada. Beyond the risk associated with elm material, I think it is probable that this pathogen also survives on plants in additional taxa, since it was formerly known for causing disease on citrus trees.
Although APHIS has classified Leptosillia pistaciae as a federal quarantine pest, I have learned of no response to detection of the pathogen on the native California shrub, lemonade berry (Rhus integrifolia), in 2019.
Rhus integrifolia – host of Leptosillia pistaciae
Has APHIS Changed its Practices in Response to Recent Detections?
We’ve known about gaps and weaknesses in APHIS’ approach for a long time. Here are specifics.
Has APHIS upgraded its attention to nematodes – as should have been prompted by detection of the beech leaf disease nematode (above) and as recommended by Kantor et al.?
Has APHIS changed any of its practices or policies in response to detection of plant and human pathogens associated with wooden handicrafts from countries other than China? Or wood pieces used for unanticipated purposes, e.g., to decorate aquaria? All 31 fungal taxa detected by one of these studies were viable despite having been subjected to various phytosanitary requirements.
USDA has no authority to regulate organisms that pose a risk to non-plant hosts, like us humans! Has APHIS contacted officials at the relevant agency?
Does APHIS respond to detections abroad when pests attack congeners of North American trees? I have blogged about several — see here, here, here and here — detected in Europe or Asia that attack cypress, magnolia, dogwood, Persea, and oaks. PestLens — an alert system created by APHIS — reported these.
How has APHIS incorporated the findings at various “sentinel garden” projects? And the wider implications of findings by Eliana Torres Bedoya and Enrico Bonello regarding findings on asymptomatic plants?
How is APHIS applying the impact assessment tools developed (for insects) by Ashley Schulz and Angela Mech? Has APHIS incorporated Kenneth Raffa’s advice about the strengths and weaknesses of various prediction tools?
I wonder whether APHIS has responded in any way to the rash of woodborer introductions on the west coast, including three species in the invasive shot hole borer complex and the Mediterranean oak borer. Has the agency explored the threat that the spotted poplar borer (Agrilus fleischeri) – another wood-boring beetle native to northern Asia – might pose to North American Populus species? Canada has twice intercepted the species on solid wood packaging material .
USDA APHIS is explicitly not a research agency. However, it claims that its decisions are science-based. In my view, this means APHIS has a responsibility to respond to scientific findings (such as those above) and to bring about research aimed at answering pertinent questions,e.g., those related to risks of pest introduction and establishment, effective detection and management technologies, etc.
APHIS has occasionally done this:
It established the NORS-DUC research facility to study what aspects of nursery management facilitate establishment of Phytophthora ramorum.
It enabled and participated in several studies of wood-borer introduction via wood packaging, including those by Robert Haack and colleagues (see blogs on this website under the category “wood packaging”).
It enabled and participated in a study of introduction pathways that included plants-for-planting – relying on 2009 data. (Liebhold et al. 2012)
Did APHIS support the study by Li et al. to evaluate the vulnerability of two oak and two pine species to 111 fungi associated with Old World bark and ambrosia beetles?
APHIS could do much more to determine whether North American trees are vulnerable to pathogens and arthropods detected on the congeners in trade partner countries. Opportunities include:
studying which North American species might be vulnerable to the growing number of the 38 new Phytophthora species detected overseas. This would be a monumental task: 216 species have been recognized in the genus. I have focused specifically on the 38 species detected by Jung, Brasier, and others in Vietnam and now the 18 Phytophthora species detected in the Alps. (I have already noted that APHIS and the states dropped any idea of regulating one of those species, P. austrocedrii).
Regarding P. ramorum specifically, scientists now recognize 12 genetic strains; 8 are in Southeast Asia, a ninth (EU2) in Europe. How likely is it that some of these will be introduced to the U.S.? Three strains are known to be established in western North American forests – NA1, NA2, and EU1.
In addition, new hosts continue to be identified. APHIS has pledged to update the host list annually. In the past I have criticized APHIS for not accepting hosts identified in the United Kingdom.
While APHIS is not well-funded, it has largely escaped budget slashing by “DOGE,” other Trump Administration cuts, and congressional decreases. Scientific expertise at the USDA Forest Service has been shrinking for decades (see Chapter 6). Now, loss of expertise has reached crisis levels. The result will be less capacity to assist APHIS in evaluating pest risks and research needs.
Earlier, I noted the importance of APHIS using its full NAPPRA authority. Unfortunately, the record is not encouraging here, either.
Since the agency gained this authority in 2011, it has adopted lists of species temporarily prohibited for importation only three times – in 2013, 2017, and 2021. I complained that the last action was tardy and provided insufficient protection to Hawai’i’s unique flora arising from multiple strains of the ‘ōhi‘a rust pathogen Austropuccinia psidii and here. Even worse, four years after promising to close the loophole that allowed continued imports of cut flowers and foliage – the most likely pathway by which the rust was introduced to Hawai`i, APHIS has not proposed the necessary rule.
Pathogens are more difficult to detect and manage than invasive insects. The “disease triangle” is complex! Numerous pathways are involved! But they also get less attention – and this reflects unwise decisions by agency leaders. I suggest that they should respond to this complexity by adding resources. Voglmayr et al. (full reference at the end of this blog) also called for more attention to pathogens. Kantor et al. noted that nematodes are also neglected.
Of course, I have repeatedly urged APHIS leadership to enhance enforcement of regulations governing imports of wood packaging. One suggestion is that it prohibit importation of Chinese wood packaging because of its 25-year record of not complying with – first – U.S. and Canadian regulations and – later – the international regulation known as ISPM#15.
Information Gaps Impede APHIS’ Domestic Program
I have criticized APHIS’ failure to find answers to several questions important to managing the sudden oak death pathogen, Phytophthora ramorum. Like the many questions listed earlier, these also need priority attention.
APHIS has regulated interstate movement of nursery stock to contain P. ramorum for over 20 years. I appreciate its creation of NORS-DUC. But it is also responsible for protecting natural systems in regions not yet invaded, e.g, in the East. APHIS should have studied these issues years ago, given the frequency with which pests spread nationwide via the nursery trade.
Other pathogen systems also have genetic variation that might be important in determining pest-host relationships. As of 2022, scientists had identified 43 haplotypes (genetic variants) of E. fornicatus s.s. worldwide, with the greatest diversity in several Asian countries (P. Rugman-Jones, pers. comm). Other species of plant pathogens also have several haplotypes.
Forests At Risk Outside of North America
North American forests are not alone in being besieged by non-native pathogens. Their numbers have been rising also in Europe and Oceania. The record is less clear in Africa, South America, and Asia.
Reports of tree pathogens in Europe began rising suddenly after the 1980s – admittedly 15 years before the WTO took effect. By 2012, more than half of infectious plant diseases in Europe were caused by introduction of previously unknown pathogens https://www.nivemnic.us/?p=5164
Antonelli et al. (full citation at the end of this blog) report that three previously undetected species of Phytophthora have been detected in European nurseries since 2016. Voglmayr et al. reported that the number of alien fungi in Austria increased 4.6-fold over 20 years. Eighty percent were plant pathogens. The introductory pathway was unclear for the vast majority. They note that differences in research efforts probably explain some discrepancies.
The ash decline pathogen, Hymenoscyphus fraxineus, has apparently been present in eastern Europe since the 1980s, so its spread has probably not been facilitated by the downsides of the WTO/IPPC system.
Other sources report recent introductions of insects to Europe. Musolin et al. reported that 192 species of phytophagous non-native insects had been documented in European Russia as of 2011. They included the emerald ash borer detected in Moscow in 2003. Some of these insects were probably introduced to Europe (outside Russia) before the WTO/IPPC system came into effect. Examples are two insects from North America that were detected in 1999 and 2000, respectively – the western coniferous seed bug, Leptoglossus occidentalis, which vectors a pathogenic fungus Sphaeropsis sapinea (=Diplodia pinea); and the oak lace bug, Corythucha arcuata.
Australia was slow to respond to detection of myrtle rust, Austropuccina psidii. Few federal resources were made available to study its impacts – although the Australian flora includes at least 1,500 species in the vulnerable plant family. Carnegie and Pegg said this experience demonstrated the need to integrate the work of agencies responsible for conservation of natural ecosystems with those determining and implementing phytosanitary policy. New Zealand initially responded more assertively, but also found little funding to support resistance breeding or even to track the rust’s spread.
The record is less clear regarding Africa, South America, and Asia.
Africa
Sitzia et al. expressed concern that bark and ambrosia beetles threaten to cause significant damage to tropical forests. Several factors contribute to these threats: the long history of plant movement between tropical regions; conversion of tropical forests that disturbs canopies, understory plant communities, and soils; and, generally, regions with fewer resources to prevent or respond to invasions.
In Africa, Graziosi et al. reported on the cumulative economic impact of invasive species and the continent’s limited capacity to prevent or respond to introductions. They don’t discuss whether pests attacking plantations of non-native trees followed those trees from their point of origin. They found that some introduced insects pose significant threats to native tree species. They mentioned the Cypress aphid, Cinara cupressi, which was attacking both native African cedar, Juniperus procera, and exotic cypress plantations. All the examples appear to have been introduced before the WTO/IPPC system took effect. All the examples appear to have been introduced before the WTO/IPPC system took effect.
Cinara cupressi; photo by Blackman & Eastop via Wikimedia
Graziosi et al. point out that South Africa plays a central role because it imports significant volumes of goods that can transport pests. At most immediate risk is South Africa’s highly diverse and endemic flora. For example Phytophthora cinnamomi is attacking native Proteaceae, which are important components of the unique Cape Floral Kingdom. Other pathogens are attacking native conifers in the Podocarpus genus, Ekebergia capensis (Meliaceae), and Syzygium trees. However, pests first introduced to South Africa often spread. Graziosi et al. name several insects and pathogens of Eucalyptus and the wood-boring pest of pine Sirex noctilio.
Pests in Asia
Available information about China is not definitive. The FAO reports that half of the most damaging forest pests are non-indigenous. They were estimated to occur over an area of 1.3 million ha and to kill over 10 million trees per year. However, the three tree-killing pests which receive the most attention are the pinewood nematode (Bursaphelenchus xylophilus), red turpentine beetle (Dendroctonus valens), and fall webworm (Hyphantria cunea). These were all introduced before the World Trade Organization was founded.
The FAO notes several non-native insects that attack native trees in India, but all were introduced decades before the World Trade Organization began. There is no discussion of tree pathogens.
Thu et al. report a growing number of pest outbreaks damaging plantations of non-indigenous trees in Vietnam. In most cases the pests are indigenous to the country. They report that almost nothing is known about pests that attack species in the highly diverse native forests.
The September 2025 meeting of the International Forest Quarantine Research Group (IFQRG) had a session devoted to the topic “Risk of international trade in plants for planting”. The specific presentations are titled
“Using molecular tools to elucidate the pathways of cryptic pests on plants for planting”
“Risk-based approach to the movement of germplasm into Australia: the luxury afforded to an affluent continent” (note my earlier blog criticizing Australian efforts re forest pests)
“Challenges in the validation of methods for detection of quarantine pathogen – P. ramorum”
“Challenges in surveillance and detection of quarantine fungal tree pathogens in European Union”
“Pathogens in trade and the risk of establishment – update”
I hope that some of these discussions begin to tackle the crucial questions I raised in this blog and earlier. Also, I hope IFQRG continues to explore these important questions.
As Wu and Raffa et al. have said, Earth’s forests cannot afford delay in finding solutions to the challenges posed by introductions of novel pathogens to naïve systems.
SOURCES
Antonelli, C.; Biscontri, M.; Tabet, D.; Vettraino, A.M. 2023. The Never-Ending Presence of
Phytoph Spp in Italian Nurseries. Pathogens 2023, 12, 15. https://doi.org/10.3390/pathogens12010015
Voglmayr, H., A. Schertler, F. Essl, I. Krisai-Greilhuber. 2023. Alien and cryptogenic fungi and oomycetes in Austria: an annotated checklist (2nd edition). Biol Invasions (2023) 25:27–38 https://doi.org/10.1007/s10530-022-02896-2
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
Michigan’s champion green ash – killed by emerald ash borer
As readers of this blog know, I worry when volumes of imports rise (scroll down the webpage to “categories”, then scroll down to the “wood packaging” category), especially when the rise is rapid and supply chains are in chaos – as they are now. As I reported a month ago, U.S. imports from China landing at U.S. west coast ports grew by significant amounts during January through April 2025 as importers sought to get their goods before a threatened strike by longshoremen and high tariffs mandated by President Trump. The blog provides specific proportional increases for the ports of Los Angeles, Long Beach, Oakland, Seattle, and Tacoma. After a dip in May and June [as reported in both the Washington Post article and that by M. Angell] – in response to President Trump announcing a 145% tariff on goods from China – imports surged again in July when this tax was postponed (see below).
These spurts in imports worried me because wood packaging from China has a nearly 30-year history of higher-than-average failure to comply with phytosanitary regulations (see Haack et al. 2022; full citation at the end of this blog; and earlier blogs). I fret that when importers are in a rush neither exporters nor importers pays much attention to whether the crates and pallets have been treated in accordance with ISPM#15 to prevent insect infestation.
The surge in imports was across the board. Indeed, other countries saw even higher growth in exports to the United States than did China. According to the Journal of Commerce (JOC), www.joc.com containerized imports from all exporters reached an all-time high in July 2025 — 2.6 million TEUs Over the six-month period January through June, 12.53 million TEUs [Robb] (otherwise measured as approximately 6.3 million 40-ft containers). JOC also recorded single-digit declines in import volumes from all regions in May and June.
In a blog in March 2025 I noted that the Department of Homeland Security’s Bureau of Customs and Border Protection (CBP) had processed 36.6 million shipping containers holding imports in Fiscal Year 2023 – which ended in September 2023. Together, Mexico and Canada provided 30% of U.S. imports in 2022. So probably ~25 million shipping containers arrived via ship from Asia, Europe, and other overseas trading partners.
Note that the CBP reports containers, while the JOC reports TEUs [TEU = twenty-foot equivalent unit; standardized measure of container]. Most sea-borne containers are actually 40 feet long; CBP numbers probably refer predominantly to 40-feet containers. The numbers reported by the two sources are not equivalent. The trends do match, however.
container ship at Hai Phong container port; photo by Nathan.cima via Wikimedia
Origins
Despite the spurts in volumes of incoming containers, total imports from China have declined from previous years. According to Angell, the 1.228 million TEU imported from China in July was 8% lower than the number of TEUs from China in July 2024. Importers have shifted to suppliers in Southeast Asia. Containerized imports from that region rose 24% over the previous July, reaching records of 542,414 TEUs in June and 581,803 in July. In fact, the U.S. imported more goods from Southeast Asia in the months March – June than from China (Wallis 2025).
The second greatest increase was in imports from countries on the Indian subcontinent. They also reached a record in July of 152,630 TEUs – 21% above July 2024.
Vietnam and India have much better records of compliance with ISPM#15 than does China: only one of 257 consignments from Vietnam and three of 1,549 consignments from India inspected over the period 2010 – 2020 harbored pests. Thus, from the perspective of introduction of non-native tree-killing insects, the shift to Southeast Asia and India is a plus. However, this improvement might not last. I expect that the 50% tariff on most goods from India that came into effect in late August 2025 will result in a steep fall-off in imports from that country.
Imports from Southern Europe also rose 7% from a year earlier to 155,587 TEUs. Imports from Northern Europe were essentially flat over the July 2024 – July 2025 period.
discarded dunnage in Houston
Ports
Shifts in trade patterns also appear in port data. The Port of Los Angeles received 542,940 TEUs in July, a 10% increase from a year earlier and the highest monthly total for the port since August 2024. However, it was Houston that saw the strongest year-over-year import growth; the 184,418 TEUs entering in July 2025 volume were 18.5% higher than the number imported in July 2024. Imports from Southeast Asia saw a 63% increase; those from China rose by 9.8% [Angell].
As you might remember, pest detections by CBP have risen at ports in America’s southeast: at the National Plant Board meeting in July, representatives of APHIS and state phytosanitary agencies expressed surprise about this finding. I reminded the group that ports in that region had been receiving higher import volumes in recent years, including from Asia through the widened Panama Canal. I added that there had been problems with dunnage in the port of Houston.
De Minimis packages
As of 29 August 2025, the United States is imposing tariffs on small-value imports that previously could enter the country tax-free. In 2016, the U.S. raised the threshold from $200 to $800. Importers of these packages not only avoided paying taxes on this newly expanded list of items. They also were subjected to minimal processing, including inspections (Chapell). This change coincided with on-line shopping becoming the norm. De minimis shipments started to dominate cargo entering the U.S. According to a press release from the Bureau of Customs and Border Protection, cited by NPR, the number of de minimis shipments grew from 140 million in 2014 to 1.36 billion in 2024.
Not coincidentally, phytosanitary officials have expressed growing concern about on-line sales of plant species considered invasive in one or more states, and exacerbated appearance of items infested by plant pests. These concerns have been voiced at National Plant Board meetings since at least 2021. At that meeting, then APHIS Deputy Administrator Osama el-Lissy said that managing
e-commerce was a priority of the new Biden Administration. The topic has been on the NPB agenda since then. Two kinds of shipments raise concern: those by North American suppliers that send plants or other items that violate regulations of the destination state, and those from abroad. All recognize that persuading foreign suppliers to comply with U.S. regulations is nearly impossible. At this year’s meeting, Acting Deputy Administrator Matt Rhoads conceded that APHIS has not yet figured out how to curtail this risk. The volume of illegal imports can be huge: an illegal shipment of tens of thousands of black pine (Pinus thunbergii) seedlings was sent to Georgia. State officials found out about the importation and stopped sale of the plants. Although the Trump Administration’s decision to end the de minimis exemption was not prompted by the plant health risks, it will probably help reduce it.
Japanese black pine bonsai at National Arboretum; photo by Ragesoss via Wikimedia
Imports during the Pandemic: will we soon see a jump in new detections?
We already know that import volumes first fell dramatically during the COVID-19 pandemic, then rebounded to record levels. According to David Lynch (citation below), in 2021 the Port of Los Angeles handled more than 535,000 incoming shipping containers in May 2021. During that month and three others in 2021, the number of arriving containers exceeded the single busiest month in 2019 (476,000) [p. 257]. Other ports also saw increased volume. Lynch discusses how this import surge stressed capacity of ports, warehouses, and transportation systems (truckers and railroads). He does not examine how this surge might have affected traders’ compliance with wood packaging treatment requirements or phytosanitary agencies’ ability to enforce those rules. Those agencies’ funding had decreased during the pandemic drought.
Five years have passed since this disruptive swing from low numbers to record-breaking quantities. Will we begin to see evidence — trees stressed by newly introduced insects or pathogens?
Wallis, K. Surging Southeast Asia volumes strain Intra-Asia Capacity. https://www.joc.com/article/surging-southeast-volues-strain-intra-asia-capacity-6078465
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
healthy eastern hemlock in Shenandoah National Park; photo by F.T. Campbell
PestLens reports newly detected insects and pathogens that seem to pose a threat to North American forests.
Insects on hemlock – Tsuga spp
a) Adelgeslepsimon (Hemiptera: Adelgidae) – found infesting Tsuga dumosa (Himalayan hemlock) trees in Bhutan.
b) bark beetle Pityokteines spinidens (Coleoptera: Curculionidae) – infesting Tsuga canadensis trees in an arboretum in the Czech Republic. Affected trees showed branch dieback, entry holes, and internal galleries.
2. Several fungi infesting loblolly pine – Pinus taeda
needle chlorosis and drying, canopy dieback, and root necrosis on loblolly pines in Brazil is caused by the fungi Ilyonectria leucospermi, I. protearum, I. robusta, and I. vredehoekensis (Sordariomycetes: Hypocreales).
PestLens is supposed to alert APHIS to threats; I hope the agency is paying attention!
The USFS Southern Research Station reports that it is investigating brown spot needle blight, caused by the fungal pathogen called Lecanosticta acicola. The report says the pathogen has been present in the U.S. for more than 100 years, but does not indicate an origin. Other sources show it as widespread in both North America and Europe. The USFS notes two recent significant outbreaks, one affecting more than a million acres of loblolly pine in the Southeast, the second on eastern white pine in the Northeast. The pathogen also infects other species. .
You can subscribe to PestLens and receive weekly alerts – go to the website.
The National Plant Board (NPB) represents the state officials responsible for preventing the introduction, establishment, and spread of invasive species called “plant pests” – including insects and pathogens that attack our native flora and invasive plants. The NPB has just held its 2025 meeting, on which I report here.
Coming to the Mid-Atlantic: NPB 2026 Annual Meeting
The next annual meeting will be in Alexandria, Virginia at the end of July 2026.I have attended these annual meetings since 2006 and always find them worth my time. They provide a wonderful opportunity to interact with the state and federal officials responsible for managing invasive plants and plant pests, and to assess regulatory issues. Contact me for more information.
The agendas focus on practical topics, such as science and technology tools, changes in APHIS policies or practices, and progress in cooperation among relevant federal agencies (i.e., the U.S. Department of Agriculture and the Department of Homeland Security’s Bureau of Border Protection) and with the states. While agricultural pest issues are stressed, tree-killing pests also get attention. Sometimes invasive plants are also discussed. The Board’s state representatives seek ways to coordinate their efforts both at these meetings and throughout the year.
Issues in the host location are part of the focus. Next year, that will be the Mid-Atlantic. The meeting is being co-hosted by the departments of Agriculture of Virginia, Maryland, Washington, D.C., and Delaware.
I expect that there will be opportunities for presenting concerns of non-governmental organizations – at least through staffed display tables and possibly other activities. I hope the many conservation organizations that have a Washington, D.C., presence will consider participating.
In Honolulu: NPB 2025 Annual Meeting
NPB’s 2025 Annual Meeting in Honolulu focused to some extent on the unique aspects of agriculture and introduced pests on remote Pacific islands. (Guam was co-host.) This blog reports on current efforts by federal and state authorities to counter bioinvasions there and around the country.
I took advantage of the meeting to visit the “Big Island” of Hawai`i to see for myself the impact of rapid ‘ōhi‘a death and enjoy the native flora (for example, the hapu tree fern – below). I posted another blog reporting what I learned there.
native Hawaiian tree ferns & ʻōhiʻa; photo by F.T. Campbell
Federal
In an earlier blog, I outlined the Administration’s proposed cuts to staff of the U.S. Department of Agriculture (USDA) and contradictory actions by Congress in the annual appropriations bills.
As that blog makes clear, the work of USDA’s Animal and Plant Health Inspection Service (APHIS) is viewed much more positively by the Trump Administration than is the USDA Forest Service. While APHIS’ funding is much more secure, staff cuts and reorganization of the USDA still have caused setbacks. APHIS is expected to lose 15% of employees – 1,180 people. Four hundred APHIS employees accepted the Administration’s deferred resignation offer. These included the leadership of many programs – including the previous Deputy Administrator, Mark Davidson. Higher up, no one has been appointed to the position of Deputy Secretary for Marketing and Regulatory Affairs.
In his report to the meeting, APHIS Acting Deputy Administrator for Plant Protection and Quarantine Matthew Rhoads noted that the Administration’s Farm Security Plan, which emphasizes efforts to combat bioterrorism, includes APHIS’ safeguarding role. However, abrupt and incomplete leadership changes hamper efforts to replace those who have left and set agency priorities. While I am cheered by the reported priority for preventing pest introductions, I fear that the focus might be quite narrow, leaving out threats to natural resources such as native forest trees.
Rhoads announced that after years of effort, the Asian longhorned beetle has been declared eradicated on 12.3 square miles of the Massachusetts quarantine zone.
Much of the presentation by Matthew Rhoads and later ones by other APHIS staff updated attendees on progress on technologies important in pest detection and control, and specific projects being carried out jointly by APHIS and NPB members (that is, state regulatory officials chosen to represent the state phytosanitary agencies). I consider the collaborative projects — begun in February 2023 – to be very important. Twenty years ago, relations between APHIS and its state counterparts were characterized by an “us vs. them” attitude.
I will summarize progress on the projects of greatest interest to those of us focused on non-native insects and disease pathogens threatening tree species. Rhodes mentioned improvements in the plant pathogen diagnostic certification program and development of improved molecular diagnostics for 45 insects and plant pathogens, including several Phytophthora species.
Joint APHIS-NPB teams have completed many risk analyses: 18 datasheets, 20 assessments, and four pathway analyses. As usual, insects – especially beetles – are the most numerous taxa detected. Many were surprised that the majority of new detections occurred in the south. When he was asked about this, Rhoads speculated that this reflected the region’s more hospitable climate and Florida’s surveillance efforts. I noted that ports in the southeast – e.g., Savannah and Charleston – are receiving higher import volumes; and that there have been problems with dunnage in the port of Houston.
Large container ship docked at Port of Savannah; photo by F.T. Campbell
Rhoads praised the federal-state strategic alliance’s project targetting illegal importation of plants purchased on-line. His example should concern us: importation of as many as 10,000 black pine seedlings to Georgia. The state stopped sale of these plants and APHIS’ investigatory unit began an investigation. This example illustrates the volume of plants that might be moving in this trade. Several states asked APHIS to offer more help in countering trafficking involving smaller numbers. All agree that no one has yet figured out an effective way to control this pathway.
A second example of successful coordination between APHIS and the states was said to be the decision to not regulate Phytophthora austrocedri, a pathogen detected in several nurseries in Oregon in 2024. Possible hosts in the Pacific Northwest include the already-depleted Port Orford cedar, and here; Juniperus californica, J. grandis, J. occidentalis, and J. maritima. Federal and state plant health officials, in coordination with the nursery industry trade association (AmericanHort), reached this decision after determining that the pathogen has probably been present in Oregon for many years and been spread to other states on the large volumes of host plants shipped. Now it will be up to states and non-governmental conservation organizations to try to detect whether this pathogen has established and devise management strategies.
New Information (as of December 2025): someone has posted on the web a written explanation of this decision by APHIS to the National Plant Board. [Visit cdn.ymaws.com, search for “Phytopthora austro”]. APHIS estimated that delimitation surveys in just one nursery would cost more than $9 million. Because the pathogen cannot be detected by visual symptoms, even tracking spread requires expensive destructive sampling of large numbers of plants. Meanwhile, thousands of possibly infected plants have been shipped from at least two Oregon nurseries in recent years. APHIS concluded that a Federal survey program for P. austrocedri would not contribute to ultimately controlling the spread or eradication of this pathogen. The agency recommended instead that natural resource agencies adopt a “protective-style approach”, focused on actively managing highest-value natural sites.
Are federal, state, and non-governmental managers of the many types of ecosystems inhabited by junipers and cypresses equipped to do this?
Ordinarily, the USFS Forest Health Protection program would be in a position to assist states which want to manage this pest (assuming its establishment). But considering the current uncertainty regarding USFS’ future, blog states cannot count on that help.
Sky Stevens (entomologist on the staff of USFS Forest Health Protection program) reported on the situation at the USFS. She noted that the Congressional appropriations bills continue funding for the agency’s research program and collaboration with non-federal entities managing forests. Still, the USFS lost 5,200 people through “voluntary” resignations and firings.
The program of greatest importance to us, Forest Health, was cut from 18 people to 8. Stevens replaced the long-time national entomologist. The comparable pathologist has retired. Stevens is struggling to make decisions regarding the pathology program, especially since diseases are inherently more difficult. While the USFS is doing lateral exchanges to fill high-need vacancies, FHP has not yet been asked what the program needs.
According to Stevens, in 2024 about 9 million acres were impacted by forest pests. The FHP program treated 1 million acres. As usual, the (European) spongy moth was the largest target based on acreage. Other non-native species targetted were emerald ash borer, goldspotted oak borer, sudden oak death, Asian longhorned beetle, hemlock woolly adelgid, and rapid ‘ōhi‘a death. See summaries of these pests’ impacts and status here.
Continuation of these projects in 2025 often became trapped in the new Administration’s funding freezes; opportune times for effective actions were often missed. On-going projects include several targetting emerald ash borer and its hosts in Oregon and black ash swamps of the Midwest and Northeast; managing sudden oak death in Oregon and California; and delimitation surveys for rapid ‘ōhi‘a death. The SOD program benefits from approximately $3 million earmarked by Congress (out of the total funding for the forest health program of $48 million).
Stevens noted that it is difficult to discuss the program’s future given the uncertainty. Program staff hope to continue issuing products that help people understand forest health in their region – not limited to federal lands.
I learned from the review of the following programs and technical tools that many were funded by the grant program under APHIS’ Plant Pest and Disease Management and Disaster Prevention program (Plant Protection Act Section 7721). Clearly, America’s efforts to prevent and respond to invasions by plant pests (including invasive plants) would be far less robust without this grant program.
boxwood (box tree) garden at Gunston Hall – an 18th Century plantation near Alexandria, Virginia (site of the 2026 NPB meeting); Photo by Roger 4336 via Wikipedia
Wendy Jin, APHIS PPQ Associate Deputy Administrator, urged states to use pest forecast models developed under the SAFARIS program. These models incorporate information on weather; pest biology, environmental needs and impact; hosts; land cover; and relevant human activities. Fifty pests have been evaluated so far, apparently including Asian longhorned beetle, spongy moth, spotted lanternfly, and boxtree moth. (All but the last are described briefly under the “invasive species” tab here.) The goal is to provide managers information about the insect’s life stage at specific times in specific localities so that they can time their surveillance and management actions. However, I am somewhat worried because the models use current and historical weather data – which might not be pertinent as the climate warms. Worse, the modelers lack sufficiently detailed data to develop models for Alaska, Hawai`i, Puerto Rico, or Guam.
Dr. Carrie Harmon (Deputy Director, National Plant Diagnostic Network) described the resources available for states use from two diagnostics tools. Both were developed under grants which are now expiring. Therefore updates and further development will depend on renewal of the grants. The National Plant Diagnostic Network (NPDN) provides accurate data and alerts about appearances of plant diseases. APHIS is said to be collaborating closely to ensure as much data as possible is shared. A separate body, the Diagnostic Assay Validation Network, is validating diagnostic assays.
A few years ago the NPB and APHIS formalized their new level of collaboration as the “Strategic Alliance, Strategic Initiative”. The Plant Board surveyed its members to gauge their feelings about several issues: 1) data-sharing issues that impede decision-making; 2) ways to strengthen coordination when dealing with on-line sales of plants or other vectors of plant pests (see the pine-Georgia example above); and 3) what structures and practices could make resolving these problems easier.
One of the resulting initiatives is an analysis of implementation of the Federal Noxious Weed program in the absence of a line-item appropriation. However, the President’s “Department of Government Efficiency” (DOGE) prompted resignations and firings, including this project’s APHIS liaison. Without a replacement, it is unclear how the analysis can proceed.
Another speaker, representing Bob Baca, Assistant Director of APHIS Plant Protection and Quarantine, warned state officials about new pressure to phase out use of methyl bromide (MB) as a phytosanitary tool. Use of ozone-depleting chemicals – including MB – has been regulated since 1988 under the Montreal Protocol. Americans use more MB for this purpose than any other country. Already manufacturers are ending its production. After mentioning substitutes under development, the speaker urged state departments of Agriculture to meet with growers and develop a nation-wide plan to weather this impending change. She noted that APHIS has no authority to require companies to produce substitutes.
The NPB leadership discussed turnover in the organization (several states are represented by officials new to their jobs); advocacy to APHIS for even better coordination and recognition of states’ need to act quickly; and efforts to expand its collaboration with other entities. A series of presentations tallied lessons learned during specific plant pest crises. These included the role of the public in pest detection; mobilizing initial responses to a new pest; and building higher-ups’ and legislators’ support for funding a “rapid response” capability before arrival of a new damaging pest.
In a separate blog I reviewed topics discussed that pertain particularly to Pacific island plant health issues.
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
stand of Miconia under albizia overstory on Big Island, Hawai`i; photo by F.T. Campbell
As I will describe in another blog, participants in the annual meeting of the National Plant Board link in Honolulu learned the basics about the uniqueness of agriculture and native species on remote Pacific islands. I want to complement this information by reminding you about other Hawaiian and Guamaian species at risk – although did not learn anything new.
As Martin and Andreozzi pointed out, the Pacific islands import nearly all their food and other consumables. Considerable interest in some quarters in Hawai`i to increase agricultural production. However, large swaths of land in the low-elevation area surrounding Pahoa on the Big Island is completely dominated by the albizia (Falcataria Molucca) [see photo above]. J.B. Friday says it is cost-prohibitive to remove these trees in order to restore agriculture in the area. Local people are concerned because in storms the trees fall onto houses and roads, causing considerable damage.
I saw numerous clumps of the notorious invasive plant Miconia calvescens. Dr. Friday told me that conservationists now focus on keeping this plant out of key areas, not trying to eradicate it completely.
area being restored by volunteers; photo by F.T. Campbell
Local people trying to restore disease-damaged forests by planting other native plants and hand-clearing invasive plants. Some of the ohia seedlings infected by Austropuccinia psidii.
ohia seedling with symptoms of ohia rust (Austropuccinia psdii); detected by J.B. Friday; photo by F.T. Campbell
Dr. Friday showed me many areas where ʻōhiʻa trees have been killed by rapid ʻōhiʻa death. Since this mortality occurred a decade or more ago, other plants have grown up. Pic In many if not most cases, this jungle includes dense growths of guava Latin the most widespread invasive tree on the islands (Potter). ‘Ōhi‘a trees continue to thrive in Hawai`i Volcanoes National Park – also on the Big Island – because the NPS makes considerable efforts to protect them from wounding by feral pigs. Demonstrates importance of fencing and mammal eradication in efforts to protect this tree species.
healthy ʻōhiʻa tree on cinder cone created by eruption of Kilauea Iki in 1959; photo by F.T. Campbell
I also saw healthy koa (Acacia koa) in the park, especially at sites along the road to the trail climbing Mauna Loa.
Regarding the wiliwili tree, I was told that it remains extremely scarce on Oahu.
wiliwili tree in flower; photo by Forrest Starr
I heard nothing about the status of naio – another shrub native to the Big Island – but on the dry western side of the island.
I rejoice that scientists are making progress in protecting and restoring Hawaii’s endemic bird species. Specifically, they are at the early stages of controlling mosquitoes that transmit fatal diseases. All 17 species of endemic honeycreepers that have persisted through the 250 years since Europeans first landed on the Islands are now listed as endangered or threatened under the federal Endangered Spp Act. The “Birds, not Mosquitoes” project has developed lab-reared male mosquitoes that, when they mate with wild female, the resulting eggs are sterile. (Male mosquitoes don’t bite, so increasing their number does not affect either animals or people.) Over time, the invasive mosquito population will be reduced, giving vulnerable native bird populations the chance to recover. Scientists began releasing these modified mosquitoes in remote forests on Maui and Kaua‘i in November 2023. In spring 2025, they began testing releases using drones. Use of drones instead of helicopters reduces the danger associated with flying close to complicated mountain rides in regions with variable weather. This project should be able to continue; the Senate Appropriations Committee report for FY26 allocates $5,250,000 for this project.
American Bird Conservancy is sponsoring a webinar about this program. It will be Wednesday, August 27, 2025 4:00 PM – 5:00 PM ET. Sign up for the webinar here
thicket of guava on the Big Island, Hawai`i; photo by F.T. Campbell
Finally, scientists are releasing a biocontrol agent targetting strawberry guava, Psidium cattleyanum, the most widespread invasive tree on the Islands (Potter et al. 2023). Distribution involves an interesting process. A stand of guava is cut down to stimulate rapid growth. The leaf-galling insect Tectococcus ovatus reproduces prolifically on the new foliage. Twigs bearing the eggs of these insects are collected and tied into small bundles. The bundles are then dropped from helicopters into the canopies of dense guava stands, where they establish and feed – damaging the unwanted host.
brown tree snake; photo via Wikimedia
Guam
Guam’s endemic birds have famously been extinguished by the non-native brown tree snake. Dr. Aaron Collins, State Director, Guam and Western Pacific, USDA APHIS Wildlife Services, informed participants at the National Plant Board meeting about the extensive efforts to suppress snake populations in military housing on the island, reduce damage to the electric grid, and prevent snakes from hitchhiking to other environments, especially Hawai`i and the U.S. mainland.
The program began more than 30 years ago, in 1993. The program now employs 80 FTEs and has a budget of $4 million per year. It was initiated because live and dead snakes had been found in shipments and planes that landed in Hawai`i and the U.S. mainland. Avoiding the snake’s establishment on Hawai`i is estimated to save $500 million per year. The program is a coordinated effort by USDA, U.S. Fish and Wildlife Service, and the Department of Defense. Probably this estimate helped advocates reverse a decision by the “Department of Government Efficiency” to defund the program.
The program enjoys some advantages over vertebrate eradication programs on the mainland. For example, since Guam has no native snakes, it can use poison, e.g., in mouse-baited traps that can be dropped from planes. A recent innovation is auto-resetting traps baited with mammals; they can electrocute numerous snakes per night.
SOURCE
Potter, K.M., C. Giardina, R.F. Hughes, S. Cordell, O. Kuegler, A. Koch, E. Yuen. 2023. How invaded are Hawaiian forests? Non‑native understory tree dominance signals potential canopy replacement. Lands. Ecol. https://doi.org/10.1007/s10980-023-01662-6
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
effects of emerald ash borer — one of the non-native pests threatening forests across the North American continent; photo by Leslie A. Brice, taken in Maryland
Forest Service: What the Administration Proposed
According to the Washington Post, the Administration’s plans for shrinking the federal government would cut employees of the U.S. Department of Agriculture (USDA) by 35% by 2026 – a loss of ~32,000 employees. Of these, the USDA Forest Service (USFS) was targetted for significant losses. The Administration proposed to end the Research and Development program, firing 1,641 employees. The State, Private, and Tribal program would lose 94% of its staff of 580 people. The National Forest System was to be cut by 30%, or 1,603 people. These and cuts to additional USFS programs would have totaled 39% of the agency’s approximately 30,000 staff.
The Administration issued a plan to reorganize USDA. This plan called for phasing out the USFS’ nine Regional Offices. Apparently only two offices would remain: a reduced state office in Juneau and an eastern service center in Athens, Georgia. Seven of the current stand-alone Research Stations would be consolidated into a single location in Fort Collins. The proposal retains two separate entities: the Fire Sciences and Forest Products Laboratories.
How Congress’ Appropriations Committees Responded
As I reported earlier, the Congress has not accepted these proposed cuts to the USFS. Under normal circumstances provisions in Congressionally-enacted appropriations legislation should prevail over the Administration’s plan, but now, who knows?
beech leaf disease — one of many non-native diseases threatening our forests that need further research; photo by F.T. Campbell
USFS Research and Development Program
The House Appropriations bill provides $301,706,000 for the research account, including $34 million for Forest Inventory and Analysis (FIA). The Senate bill provides more for the overall research program — $308.5 million; but a little less — $32 million – for FIA. I remind you that FIA data inform us about changes in the forest, including damage caused by introduced insects and pathogens. But these data do not identify or disseminate information about how such threats might best be countered.
The Senate bill specifically retains the USFS’ five regional offices and experimental forests. The report accompanying the bill specifies funding for several issues, especially needle blights on loblolly pine and western conifers and poor regeneration of white oak (Quercus alba). The only other topic of research mentioned in the bill is fire research. I fear that might led to decreased attention to non-fire aspects of introduced tree-killing insects and pathogens – which collectively threaten a similarly sized area of America’s forests.
USFS State, Private, and Tribal Forestry program
The House bill provides $281 million for the forest health program. The bill specifies that this funding “includes forest health management, invasive plants, and conducting international programs and trade activities.” This would seem to restore funding for the Forest Health Management program – both the “cooperative lands” and “federal lands” subprograms. However, I found no language specifying funding levels for each subprogram.
The Senate bill provides $38 million more — $319.5 million — for the forest health program. The report specifies that the Cooperative lands forest health management program should be funded at $42 million. However, the Appropriations Committee allocated significant proportions of this total to specific projects. Nearly a quarter of the appropriation targets the spruce budworm outbreak in the eastern U.S. Also, $2 million is earmarked for management of the sudden oak death pathogen in the forests of Oregon and California. Another $3 million funds a pilot program for management of the highly invasive plant cogongrass. Other priorities are programs targetting Western bark beetles and invasive woody plant species – although no funding levels are specified.
dead whitebark pine at Crater Lake National Park; photo by F.T. Campbell
The Senate bill also provides $19.6 million to support Congressionally-directed components of Forest Resource Information and Analysis; I don’t understand whether this is within or separate from the FIA program.
Under the National Forest System, the Senate bill instructs the USFS to spend at least $2 million per year on recovery of species of plants and animals listed under the Endangered Species Act, presumably including whitebark pines.
Animal and Plant Health Inspection Service
The USDA Animal and Plant Health Inspection Service (APHIS) is relatively well-off under the Administration’s plans. This agency is expected to lose 15% of employees – 1,180 people. According to Acting Deputy Administrator for Plant Protection and Quarantine Matthew Rhoads, 400 APHIS employees have accepted the Administration’s deferred resignation offer. Leaving are many program leaders – including the previous Deputy Administrator, Mark Davidson. While APHIS is allowed to hire to refill some positions, the future remains uncertain. I note a positive here: the new Farm Security Plan emphasizes efforts to combat bioterrorism, including APHIS’ safeguarding role. While I welcome that priority, I fear that the focus might be quite narrow, leaving out threats to natural resources such as native forest trees.
The impact of the proposed USDA reorganization on APHIS is unclear. The plan envisions continued reductions of the workforce and moving more than half of the remaining USDA employees away from Washington, D.C. to five regional offices.
APHIS also has done well under the House and Senate appropriations process. The House Appropriations Committee issued a press release touting its work as “Champions of U.S. farmers, agriculture, and rural communities”. The first example of this supportive effort reads: “Continuing critical investments in agricultural research, rural broadband, and animal and plant health programs.” Funding for APHIS is described as supporting the Trump Administration and its mandate from the American people. The Office of Management and Budget is said to have prioritized protecting American agriculture from foreign pests and diseases.
The Senate’s report instead cites traditional justifications for funding APHIS. It said that the appropriated funds will help protect the nation’s animal and plant resources from diseases and pests. (As usual, the examples cited are all animal diseases: chronic wasting disease, new world screwworm, and avian influenza.)
The reports accompanying both bills say agricultural quarantine – preventing pest introduction – is an important responsibility of the federal government. I am cheered by this statement since the Trump Administration puts such emphasis on shedding responsibilities.
Unlike the USFS, funding levels for most APHIS programs are unchanged from this year. (Of course, inflation has reduced the amount of work that can be carried out using the same amount of money.) The following table shows funding for programs of interest during the current year (FY2025) and levels proposed by the House and Senate bills for Fiscal Year 2026 (which begins on October 1).
Figures in millions of dollars (rounded up)
FY2025 enacted FY26 House FY26 Senate
APHIS total $1,148 $1,146 $1,168
Plant health subtotal $387.5 $388.6
Agric. quarantine $35.5 $35.5 $35.5
Field crop and rangeland $12 $11 $11.5
Pest detection $29 $28.5 $29
Methods development $21.5 $21.5 $21.5
Specialty crops $206.5 $216.3 $208.5
Tree and wood pests $59 $59 $58.6
Emergency preparedness and response* $44.5 $44.5 $44.3
* this fund is apparently for both animal and plant emergencies
The Senate and House bills contain identical language authorizing the Secretary “in emergencies which threaten any segment of [US] agricultural production …, [to] transfer from other appropriations or funds available to the agencies or corporations of [USDA] such sums as may be deemed necessary, to be available only in such emergencies for the arrest and eradication of contagious or infectious diseases … in accordance with sections … 431 and 442 of the Plant Protection Act … and any unexpended balances of funds transferred for such emergency purposes in the preceding fiscal year shall be merged with such transferred amounts”. The House report reminds the Administration that this language means that the emergency fund is intended to enhance, not replace, use of funds transferred from the Commodity Credit Corporation when confronting pest or disease outbreak emergencies. I have long sought increased funding for APHIS to respond quickly when a new invasive organisms is detected. Such flexibility is necessary because the regular process for adopting an appropriation stretches over about three years.
Also, both bills support continuation of APHIS’ feral swine management program. However, they prioritize funding projects in areas with the highest pig populations. I think this is backwards from the perspective of efficiency – although it might build political support for the program.
The House report mentions management of Arundo canes, said to be depleting groundwater levels in western states; eastern spruce budworm in the Northeast; spread of the southern pine beetle and spotted lanternfly; and invasions by the non-native shrub glossy buckthorn (Frangula alnus).
The Senate report notes that two strains of the sudden oak death pathogen Phytophthora ramorum and here – the EU1 and NA1 strains – pose major threats to Douglas-fir-tanoak forests in Oregon and California and the associated quarantines restrict exports of logs. Therefore, the report says funding for addressing this threat should be no lower than the FY24 level. (Oregon senator Jeff Merkley is the top Democrat on the Agriculture Appropriations subcommittee.)
I am thrilled to see that the House report requires APHIS to report within a year on recommendations to enhance existing protocols to better protect Hawai`i from bioinvasion. The report is to evaluate the feasibility of APHIS working with the state to improve biosecurity, prevent invasive species establishment, and mitigate damage from those already there. The report is to evaluate the risk of invasive species arriving via movement of people, baggage, cargo, and other items.
endemic honeycreepers of Hawai`i
Finally, the “Big Beautiful Bill” adopted by the Congress in June, increased funding for APHIS’ Plant Pest and Disease Management and Disaster Prevention (Plant Protection Act Section 7721) from $75 million to $90 million – but only for Fiscal Year 2026. This grant program continues to be crucial to funding vital programs. This year the program has funded more than 300 projects. I wonder – might forest pathologists prepare a proposal for next year that would fund a study to improve America’s phytosanitary program regarding pathogens? Two possible study topics might be 1) evaluating the efficacy of APHIS’ current regulations in preventing introduction of fungal pathogens, oomycetes, bacteria, viruses, and nematodes on imported plants and/or 2) identifying currently unknown microbes resident in regions that are important sources of origin for traded plants, vulnerability of hosts in the U.S., and new technologies for detecting pathogens
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
