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Current California Oak Mortality Task Force Newsletter: February 2026

(Printable COMTF Report February 2026)

Editor’s note. In this issue, we summarize the status of Phytophthora ramorum in 2025 for Oregon forests, California’s SOD Blitz, the United Kingdom, nurseries, and landscapes.

Monitoring and Management in Oregon – 2025 in Review

The following is an update on P. ramorum findings and management activities in 2025. Thanks to Sarah Navarro, USDA Forest Service, Region 6, sarah.navarro@usda.gov, and Gabi Ritokova, Oregon Department of Forestry, gabriela.ritokova@odf.oregon.gov, for this update.

Northern SOD Infestations. In 2025, new infestations were found between Rogue River and Port Orford. Altogether, 51 new infested sites were detected outside of the 2015 SOD Quarantine. These new detections triggered an immediate expansion of the SOD Emergency Quarantine Boundary. The area has expanded to 289 square miles. ODF is working closely with landowners affected by the new emergency quarantine boundary and infested sites to prioritize treatments. Seven of the new sites are on USFS lands and are the top priority for 2024 and 2025 treatments, while two of the new sites are on BLM lands and are the top priority for 2025 treatments. Infected trees from outlier sites were submitted to the Oregon Department of Agriculture and then to USDA APHIS for final confirmation per official protocols.

2025 Stream Baiting. 56 stream baits were installed the week of April 24, 2025. Streams in the Myers Creek, Hunter Creek, and Gold Beach areas were not monitored this year. New streams along the Sixes and Elk Rivers were added for increased monitoring of high-priority areas. Stream baits WA-12 and WA-114 will continue to be used as positive control streams for NA1 and EU1, respectively. Altogether, 22 streams tested positive for P. ramorum through plate culture methods, and eight streams tested positive for P. ramorum by PCR. These stream baits will now be plated to culture the pathogen. Notable positives include all three stream baits in the upper Winchuck area, including Bear Creek, Fourth of July Creek, and East Fork Winchuck River. Five of the new stream baits along the Elk and Sixes rivers have tested positive for PCR and will be monitored closely.

2025 Aerial and Ground-based Detection Surveys. The Oregon Department of Forestry contracted with GeoTerra, Inc. to acquire high-resolution imagery for 2025. The imagery was delivered in mid-September, and SOD Foresters have begun the pan-and-scan methodology across the 1021 square miles covered by the imagery. Additionally, USFS and ODF staff completed four helicopter surveys in 2025 January, May, and October flights focused on high priority areas of the Sixes River, Elk River, and Nail Keg (Rogue River area). ODF staff completed the annual fixed-wing survey on July 2. The Generally Infested Area was not flown during this survey and will be covered by a pan-and-scanning of the high-resolution imagery. A follow-up helicopter flight was completed on August 14th, and all points identified in the fixed-wing survey were flown over. On the ground, 495 samples were collected in 2025, of which 170 were positive for P. ramorum (Figure 1).

Eradication Treatments for 2025 Infestations. In 2025, 54 new infestations were detected at or beyond the Generally Infested Area. Assuming a 300-600 ft treatment buffer, the approximate areas of 2025 treatment are as follows:

• Private – 44 infestations = 511 ac
• Bureau of Land Management – 2 infestations = 104 ac
• State – 3 infestation = 19 ac
• US Forest Service – 5 infestations = 41 ac

Altogether, in 2025, the Oregon SOD Program completed treatments on 202 acres.

2025 Ramorum log study. The objective of this study is to determine the viability or persistence of P. ramorum in felled tanoak trees. In late 2024 and early 2025, 45 infected tanoaks were identified in China Creek and Crew Canyon to be monitored for over twelve months. Of these trees, only 33 were felled in mid-April, followed by two periods of resampling in August and November. The remaining twelve trees were damaged during the unit harvest and, therefore, were unsuitable for the study. In the fall of 2025, we decided to replicate the effort in wetter conditions, since some trees from the pilot study dried out in the sun, and therefore don’t represent winter conditions. In November, an additional 45 infected trees were felled in Myers Creek and Myrtle Creek. These trees will be resampled every three months: in February, May, and August 2026, to determine how long P. ramorum persists in logs.

Is the cure worse than the disease? Ecosystem resilience in the face of sudden oak death. Jared LeBoldus, Oregon State University, presented this during the OSU winter Botany and Plant Pathology seminar series. To understand the ecological impacts of SOD on the mixed conifer forests of southwest Oregon, a permanent plot network was established in 2020. The plots encompass healthy tanoak forests, infected tanoak forests, and tanoak forests treated for SOD. Within this 88-plot network, plant demographics, soil characteristics, microbiomes, disease severity, and wildlife use are being monitored using a variety of approaches.

California Wildland Monitoring: 2025 SOD Blitz

The 2025 SOD Blitz citizen science effort led by the Garbelotto Lab at UC Berkeley found that P. ramorum is currently at epidemic phase in the coastal counties, perhaps because of abundant precipitation during recent winters and/or longer precipitation duration into the spring months. The percent of samples found positive doubled for the second year in a row, indicative of this epidemic phase, and the mean percent of bay laurels and/or tanoaks found positive was 26.2%. Typically, when this percentage is above 20%, true oaks are at increased risk of infection from proximity to these transmissive taxa. Overall, locations at high risk of true oak infection include Big Sur, western Sonoma County, the Santa Cruz Mountains, Carmel, northern San Francisco, the San Francisco Bay Peninsula, Marin County, Santa Cruz County, and Del Norte County. In 2024, the NA2 strain of P. ramorum was found for the first time not only in Del Norte County, but also at five locations in the Bay Area. The 2025 SOD Blitz effort documented that these infestations are larger on average than most NA1 infestations. It has been documented that NA2 is favored over the other strains by warmer temperatures, which could have implications for pathogen spread in a warmer future climate as well as farther to the east in California. For more information, including a detailed a breakdown of infection rates by locality, refer to the Garbelotto Lab website at https://sites.google.com/berkeley.edu/matteogarbelottolab/sod.

Monitoring and Management in the United Kingdom – 2025 Year in Review

Following are short updates on P. ramorum (and related pathogen) research, monitoring, and management in the United Kingdom in 2025. COMTF expresses gratitude to the update providers, whose contact information appears at the end of each one.

Forest Research. Forest Research has tested ~850 samples in the survey year to date (April – Nov 2025) from Phytophthora surveillance undertaken by the Tree Health teams in England, Wales and Scotland. The samples received for testing were predominately (~75%) larch (Larix) species, with other species tested commonly including (but not limited to) sweet chestnut (Castanea sativa), Rhododendron ponticum and Vaccinium myrtillus. All samples are now routinely screened using multiplex qPCR for P. ramorum, P. pseudosyringae and P. pluvialis, with isolation and sequencing also undertaken for non-larch species. The multiplex assay was developed in part due to the increasing incidence of P. pseudosyringae findings on larch, which over the last 5-10 years has not only been found more commonly, but may be causing levels of damage similar to P. ramorum at some locations. This survey year, around a third of samples received from the survey teams in Great Britain have so far tested positive for P. ramorum, with a similar proportion positive for P. pseudosyringae. Only 1% of samples tested positive for P. pluvialis but surveillance focus in recent years has moved away from this species. For more information contact Mick Biddle, mick.biddle@forestresearch.gov.uk, or Joan Webber, joan.webber@forestresearch.gov.uk.

England – Forestry Commission. The 2025 Phytophthora ramorum aerial surveillance program surveyed over 34,738 Ha of larch across England. This generated approximately 200 targets for follow-up ground surveillance. At the time of this report, ground surveillance has discounted P. ramorum infection at a majority of target sites. Infected sites are predominately located in the Southwest, East Midlands and Northeast, in the vicinity of previously confirmed infections. The number of infested sites in 2025 is lower than previous years, continuing the downward trend seen since 2022. Similarly, symptom levels at infested sites are low compared to previous years (perhaps due to the exceptionally hot, dry weather conditions for much of 2024). Conversely, the number of symptomatic sites yielding exclusively Phytophthora pseudosyringae positive results has increased across England this year. For more information contact Brontë Thomas, bronte.thomas@forestrycommission.gov.uk.

Wales – Natural Resources Wales. In Wales in 2025 we identified 282 hectares of symptomatic larch forest. This is consistent with last year, but both 2025 and 2024 represent a significant drop off from the previous ten years, where areas over 1,000 hectares were regularly identified for follow-up survey. This is likely due to the main larch forests being infected already, and the remaining areas are smaller and more scattered. Over 90% of symptomatic sites visited resulted in finding Phytophthora pseudosyringae, with only a handful of P. ramorum findings, which continues and expands a trend from 2024. Felling Notices are not being issued on sites infected with P. pseudosyringae as it is not a quarantine organism, despite causing significant damage (Figure 2). In light of both diseases now being well established across the whole country, the Welsh Government are working on an update to the P. ramorum strategy, likely due sometime in early 2026. For more information contact Sam Milner, Sam.Milner@cyfoethnaturiolcymru.gov.uk.

Scotland – Scottish Forestry. The 2025 P. ramorum aerial surveillance season in Scotland was completed earlier than anticipated by the end of August, due to better-than-expected weather conditions. Over 480 suspect larch target sites were created (predominantly through aerial surveillance, but a small number identified on the ground including through TreeAlert reports), almost all of which have now been visited. Currently 245 of these have returned positive for P. ramorum (the 2024 season had 249 positive sites), indicating a continued trend of reduction in number and intensity of infections since peaks in 2020/2021 (over 600 positive sites). All new positive sites were in proximity to previously infected larch, mostly clustered in the south and southwestern regions (particularly the Cowal and Kintyre peninsulas) and islands of Mull and Skye. An optimistic note was that no new infected larch was identified across large regions of northern and eastern Scotland in spite of potentially conducive weather for Phytophthora later in the summer of 2024. A distribution map of P. ramorum Statutory Plant Health Notices is available here: Ramorum disease | Scottish Forestry.

Unlike other parts of Great Britain, Scotland has had limited findings of P. pseudosyringae on larch during 2025 – as also observed in 2024. Two P. pseudosyringae findings in the past year have been associated with bleeding cankers on stems of Betula spp. The majority of larch sites with P. pseudosyringae identified in 2024 also yielded evidence of P. ramorum with subsequent investigation and sampling – similar reinspection and resampling work will take place on 2025 sites. For more information contact Barnaby Wylder, Barnaby.Wylder@forestry.gov.scot.

Northern Ireland – Department of Agriculture, Environment and Rural Affairs. The annual aerial survey in Northern Ireland took place on June 18-19, 2025. Following analysis of the aerial photographs four forests were identified for follow-up in respect of P. ramorum. At one of these sites Phytophthora pseudosyringae was confirmed.

In 2025 P. ramorum EU2 lineage was identified in Araucaria araucana (it has previously been recorded from this host in Scotland in previous years). At the same forest P. ramorum was detected in Larix spp. and Tsuga heterophylla, with P. pseudosyringae also detected in Larix spp. Across the calendar year 2024 and up to October 2025 more cases of Phytophthora pseudosyringae have been confirmed in Larix spp. than cases of Phytophthora ramorum. In 2025 P. pseudosyringae has been confirmed in two further forests within Northern Ireland to the north and east of the first detection. For more information contact Aoife Smith, aoife.smith@daera-ni.gov.uk.

Nurseries and Managed Landscapes – 2025 Year in Review

First P. ramorum find in Minnesota nursery. In late 2025, University of Minnesota researchers from the Invasive Terrestrial Plants and Pests Center identified Phytophthora ramorum while working on a multi-year project to detect a variety of invasive forest pathogens with the potential to damage Minnesota’s landscapes and cause significant economic loss. This was the first detection of the pathogen in Minnesota. The pathogen was identified from a sample the researchers collected from a plant at a Hennepin County nursery in July, and later confirmed by the Minnesota Department of Agriculture (MDA) Plant and Seed Laboratory. The plant was destroyed and follow-up samples from plant hosts, water, and soil collected in September were all negative for the pathogen, though State officials will continue to monitor the site.

California Department of Agriculture P. ramorum Nursery Program 2025 summary report. The California Department of Food and Agriculture (CDFA) receives funding from the United States Department of Agriculture (USDA) to administer the cooperative Phytophthora ramorum (P. ramorum) program. The CDFA assists and reimburses the county agricultural commissioners as they enforce Federal Domestic Quarantine 7 CFR 301.92 and California Code of Regulations 3700 regulations at the 308 establishments regulated for P. ramorum in California (see Table 1). Program funding allocated to the CDFA for the P. ramorum program is $1,308,771 for fiscal year 2025/2026.

Approximately 8,277 P. ramorum program samples were submitted to the CDFA Plant Pest Diagnostics Laboratory for processing in 2025. There were 20 samples determined to be positive for P. ramorum in 2025 (see Table 2).

Enhanced inspections requiring increased numbers of samples to be collected twice a year are required at previously positive nurseries that ship P. ramorum host material out of the quarantined area. These biannual inspections require samples to be collected based on the number of host plants in the nursery. A nursery with 20,000 host plants is required to collect 322 samples biannually. In 2025 there were nine nurseries undergoing biannual inspections in California. For more information, please contact Carolyn Lambert, carolyn.lambert@cdfa.ca.gov.

Oregon Department of Agriculture P. ramorum Nursery Program 2025 summary report. In 2025, the Oregon Department of Agriculture (ODA) Phytophthora ramorum Nursery Program worked with eight interstate shippers under federal compliance agreements (7 CFR 301.92). These nurseries are in Washington (3), Marion (1), Lane (1), and Clackamas (2) Counties. The ODA also held compliance agreements with four intrastate retail shippers, which are regulated under Oregon state quarantine requirements (7 CFR 301.92 and OAR 603-052-1230). These nurseries are in Clackamas (2), and Lane (2) Counties.

Spring compliance surveys were completed by the end of April (see Table 3). The ODA tested 1,350 foliar samples for P. ramorum, of which 29 tested positive. The Confirmed Nursery Protocol delimitation work was conducted on 7 nurseries that tested positive. A total of 1,382 foliar samples were taken, of which 156 tested positive. The ODA did eight trace inspections in April and May 2024 and found 79 positive P. ramorum foliar samples. These trace inspections resulted in 4 interstate nurseries and 2 intrastate nurseries being added to the program.

Fall compliance surveys were completed by end of November. The ODA tested 2,631 foliar samples for P. ramorum, of which 14 tested positive. The Confirmed Nursery Protocol delimitation work was conducted on 3 nurseries that tested positive. A total of 263 foliar samples were taken, of which 48 tested positive. The ODA did one trace inspection in December 2025 and found 1 positive sample. This trace inspection resulted in one nursery that is pending to be added to the program.

To be released from the program, nurseries must achieve six consecutive negative results from compliance inspections over three years. One interstate nursery In Marion County was released from the program after the Fall survey. One intrastate nursery in Lane County closed permanently.

Going into 2026, the ODA will continue implementing the CNP on the nursery where positive foliar samples were found. For more information, please contact Kevin Bailey, kevin.f.bailey@oda.oregon.gov or Emily Perkins, Emily.perkins@oda.oregon.gov.

Washington State Department of Agriculture (WSDA) P. ramorum 2025 summary report. In 2025, the Washington State Department of Agriculture (WSDA) processed over 550 plant, soil, and water samples collected within the state (see Table 4). WSDA inspected nurseries that ‘opted-out’ of the Federal DA-2014-2 regulations and can no longer ship interstate. Host material at these sites appeared free of symptoms and no samples were collected, and WSDA confirmed none of the ‘opt-out’ nurseries are shipping interstate.

WSDA Plant Services staff conducted six Trace Forward investigations and collected symptomatic plant samples from out of state positive nurseries. Two of the investigations yielded positive plant samples. Both positive sites were intrastate nurseries that completed the Confirmed Positive Nursery Protocols. A botanical garden in WA observed symptomatic plants in their incoming plant quarantine area, WSDA collected samples and confirmed two positive plants. As a result, Trace Back investigations were conducted at two Washington Nurseries; samples were collected and found negative.

For more information contact Haley Palec, HPalec@agr.wa.gov.

Research

Hossain, O., Mainello-Land, A., Wang, Y., Mativenga, B., Jamalzadegan, S., Xu, J., Ristaino, J.B., Razavi, S., Li, F., and Wei, Q. 2025. Smartphone-Based Colorimetric VOC Sensor for Early Detection of Phytophthora Ramorum in Rhododendrons. ACS Sensors 2025. https://doi.org/10.1021/acssensors.5c02872.

Abstract: Traditional plant pathogen detection often relies on molecular technologies, which allow species-level detection but are often time-consuming. Plant volatile organic compounds (VOCs) have recently been harnessed to assist in disease detection and plant health monitoring. However, current VOC detection methods are unsuitable for field use due to the need for expensive laboratory equipment and slow processing times. To address this, we developed a portable paper-based colorimetric sensing technology for early detection of ramorum blight in rhododendron caused by Phytophthora ramorum. This colorimetric sensor array, which includes nanomaterials and organic dyes, was optimized to detect alcohol, terpene, and ester, key VOC biomarkers emitted by infected rhododendron leaves. Color quantification was done quickly by smartphone imaging. Principal component analysis (PCA) was used to cluster and classify individual plant volatiles. Our VOC sensing platform detected ramorum blight 2 days after inoculation, aligning with real-time loop-mediated isothermal amplification (LAMP) analysis. Moreover, the platform distinguished pathogen-induced VOCs from those produced by nonbiological stresses such as drought and mechanical damage. This noninvasive diagnostic technology demonstrates significant potential for disease detection in the field.

Mainello-Land, A., O’Hanlon, R., Carbone, I. Ristaino, J.B. 2026. Evolutionary Relationships and a T-BAS Interactive Phylogeny of Emerging Lineages of the Plant Pathogen Phytophthora ramorum. Phytopathology https://doi.org/10.1094/PHYTO-07-25-0248-R

Abstract: The spread of Phytophthora ramorum, the causal agent of Sudden Oak Death and Sudden Larch Death, has resulted in a destructive loss of trees, woody shrubs, and ornamentals in nurseries and forests in the US, Canada, and Europe since the late 1990s. Twelve lineages of P. ramorum are described that vary in global distribution and virulence. Herein, we present a maximum likelihood phylogeny for P. ramorum inferred using IQ-TREE and Tree-Based Alignment Selector Toolkit (T-BAS). The phylogeny was generated based on six loci (avh120, avh121, btub, gweuk.30.30.1, hsp90, and trp1). This phylogeny of P. ramorum improves on previous phylogenies since it is dynamic and interactive and incorporates a diverse set of all known global lineages from the US, Europe (NA1, NA2, EU1, and EU2), and ancestral lineages from the putative native range in East Asia. The phylogenetic relationships inferred in the T-BAS tree support lineages NP1 and NP2 of P. ramorum as ancestral to NA1 and NA2 lineages found in North America. In addition, East Asian IC1, IC2, IC3, and IC4 lineages are ancestral to EU1 and EU2 lineages found in Europe. We used sequence data generated from isolates of P. ramorum collected from Ireland and Northern Ireland and placed them accurately in the tree. The P. ramorum phylogeny is available through T-BAS within the DeCIFR platform. This “interactive phylogeny” can be used by the research community to rapidly update and better reflect the evolutionary relationships of new lineages of P. ramorum.

Taylor, M. 2023. An approach to estimate climate suitability for Phytophthora ramorum and Phytophthora pluvialis across the UK. Fera Science Ltd. Crown Copyright 2023, Met Office. https://hadleyserver.metoffice.gov.uk/Phytophthora/data/phytoReport.pdf

Executive Summary:

• This report and the associated web tool have been developed to provide easily accessible estimates of the spatial and temporal suitability of climate for Phytophthora ramorum and Phytophthora pluvialis across the UK.
• This report details the methodologies used to estimate climate suitability indices for ramorum and P. pluvialis. Sensitivities of the pathogens to daily climate variables (temperature and relative humidity) derived in previous studies were used with 1km gridded UK climate data to estimate the indices across the UK.
• Accompanying the report is an interactive web tool (‘Phytophthora climate risk tool’, https://hadleyserver.metoffice.gov.uk/Phytophthora/), developed to enable users to explore the ramorum and P. pluvialis indices and the associated climate data across the UK from 1991 to 2021. Further years can be added in future if required.
• Information provided via the web tool can support the understanding and management of risks to UK trees and ecosystems posed by the ramorum and P. pluvialis pathogens.
• Daily changes in climate can also be compared with the number of suitable days per month for individual years and regions, enabling users to make general assessments of the timing of suitable conditions in regions of interest and understand if the locations most at risk from these pathogens are shifting significantly due to climate variability or remaining relatively constant from year to year.
• The web tool provides functionality for the mapped data to be downloaded for inclusion into reports and/or layered with other relevant information, e.g. pathogen observation data. This enables users to undertake more detailed analyses, including to understand the potential of compound risks from both pathogen and other risk factors across the UK.
• This initial study could be improved upon for future developments by:
  • Comparing ramorum and P. pluvialis risk indices with other risk indices,
  • Including observations where the pathogens have been observed across UK,
  • Adding further Phytophthora species, where risk indices are available,
  • Including other relevant information on the web tool, e.g. vulnerable plant species,
  • Adding higher-resolution detail for high-risk areas, e.g. topographic or microclimate,
  • Including indices estimated with future climate change scenarios to enable understanding of the potential future severity and changes in risk.
• Further developments to the methodologies and web tool would need to be conducted in collaboration with a wide range of Plant Health and particularly Phytophthora experts and codesigned with the organisations and individuals who are responsible for managing these risks to ensure robust scientific estimates of risk are provided in a way that is most useful and useable by the users.

Related Research

EFSA Panel on Plant Health (PLH). 2025. Commodity risk assessment of Castanea sativa plants from the United Kingdom. EFSA Journal. 2025(23):e9804. https://doi.org/10.2903/j.efsa.2025.9804

Abstract: The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. This Scientific Opinion covers plant health risks posed by graftwood, whips, bare root plants and potted plants of Castanea sativa imported from the United Kingdom. The assessment was performed considering the available scientific information, including the technical information provided by the UK. All pests associated with the commodities were evaluated against specific criteria. Three EU regulated pests (Cryphonectria parasitica, Dryocosmus kuriphilus, Phytophthora ramorum), present in the UK and associated with the commodity, were considered relevant for this opinion. One pest that is not regulated in the EU (Phytophthora kernoviae) fulfilled all relevant criteria and was selected for further evaluation. For the selected pest, the risk mitigation measures described in the submitted technical dossier were evaluated. An expert judgement was given on the likelihood of pest freedom taking into consideration the risk mitigation measures acting on the pest, including uncertainties associated with the assessment. The degree of pest freedom varied among the commodities evaluated, with P. kernoviae being most frequently expected on the imported bare root and potted plants. The Expert Knowledge Elicitation indicated with 95% certainty that 9060 or more units per 10,000 will be free from P. kernoviae.

EFSA Panel on Plant Health (PLH). 2026. Commodity risk assessment of Lonicera var. pileata, Lonicera ligustrina var. yunnanensis and Lonicera periclymenum plants from the United Kingdom. EFSA Journal. 2026(24):e9805. https://doi.org/10.2903/j.efsa.2026.9805

Abstract: The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. This Scientific Opinion covers plant health risks posed by (a) rooted plants in pots and (b) bare root plants and whips of Lonicera ligustrina var. pileata, L. ligustrina var. yunnanensis and Lonicera periclymenum from the United Kingdom (UK). The assessment was performed considering the available scientific information, including the technical information provided by the UK. All pests potentially associated with the commodities were evaluated against specific criteria. Five EU-quarantine pests [honeysuckle yellow vein virus (HYVV, Begomovirus macrotylomae), Bemisia tabaci, Meloidogyne fallax, Phytophthora ramorum and Scirtothrips dorsalis], present in the UK and which could be associated with the commodity, were considered relevant for this Opinion. No pests non-regulated in the EU were identified to be selected for further evaluation.

Horrocks, K.J., Romeis, J., Collatz, J. 2025. Environmental impacts of agricultural pest insects: five case studies reveal overlooked impact mechanisms and specify knowledge gaps. NeoBiota 104: 251-279. https://doi.org/10.3897/neobiota.104.158217

Abstract: Invasive species can cause environmental impacts through various mechanisms. Assessing their impact can inform management decisions and illuminate risks to non-invaded areas. Research on the environmental impacts of invasive insects is heavily focused on a few well-known examples, with agricultural pests in particular receiving little attention. We aimed to investigate whether evidence for environmental impacts of insect pests of agriculture may be overlooked. We conducted in-depth literature reviews of three globally relevant insect agricultural pests–Halyomorpha halys, Helicoverpa armigera, and Spodoptera frugiperda. For comparison, we reviewed two forest pathogens known for their environmental impacts–Bursaphelenchus xylophilus and Phytophthora ramorum. We identified many published articles containing evidence of environmental impacts among the three insect agricultural pests that were not captured by existing reviews on invasive insects, with some demonstrating high levels of impact severity. Crucially, a preponderance of the identified articles did not directly address the findings in relation to environmental impacts. As expected, we recorded more conspicuous examples of environmental impacts among the case-study forest pathogens, though we also identified underappreciated impact mechanisms. We further provide evidence that supports the importance of considering management interventions as a key mechanism of non-target environmental impacts. This review raises awareness about the underreported environmental impacts of agricultural insect pests and specifies knowledge gaps that should guide future research.