Santa Monica Mountains National Recreation Area (SMMNRA) has suffered its fair share of fires over the past couple decades. The 2018 Woolsey fire burned close to 90% of National Park Service (NPS) land and the recent Palisades Fire was one of the most destructive fires in Los Angeles County history. Over 70% of the 150,000-acre recreation area has burned since 2007. Excessive fires at SMMNRA are an expression of a human influenced environment and a foreshadowing of what’s to come. Our program has seen success with the control of target invasive species like Italian thistle, yellow star thistle, and sweet fennel. And, we have seen successful control of flammable annual grasses through mechanical mowing operations. Our focus now is to build a large-scale restoration program and repeat our successes to make lanscape-level change. Perhaps a silver lining of recent fires is that they sparked a passion for conservation among people of the Los Angeles Region, bringing support from dozens of partners and thousands of volunteers. This support has resulted in the competitive and restorative planting of more than 200,000 plants, weed treatments on over 4,000 acres, and the development of a robust native seed program designed to recover areas burned by future wildfire. In this talk, I share how recent fires have set in motion a proactive restoration program aimed at building capacity for successful recovery in the world’s largest urban national park.

Medusahead (Elymus caput-medusae) and barb goatgrass (Aegilops triuncialis) are invasive annual grasses that reduce rangeland health and productivity in California. They accumulate high silica levels as they mature, becoming unpalatable to livestock, and are slow to decompose. Livestock avoid them for more desirable forage, leading to dense thatch layers that suppress desirable forage and facilitate further spread. Since both species rely on seed production to persist, disrupting this cycle can help reduce infestations. While herbicides and mechanical control are proven methods, research suggests that high-intensity, short-duration grazing in mid-spring, when the plant has invested energy into growth but has not yet developed high silica levels nor viable seeds, is also effective. This approach can save labor and convert undesirable forage into weight gain. Virtual fencing (VF) is an emerging precision agriculture tool that enables targeted grazing without physical fences. Users rapidly define VF boundaries remotely and send them to GPS collars worn by livestock. Collars use audio cues and mild electric pulses to contain livestock with more intention than traditional fencing allows. In UC Cooperative Extension trials, livestock quickly adapt to VF boundaries. We tested whether VF could successfully concentrate cattle on medusahead and barb goatgrass. In both cases, livestock remained in the VF nearly 100% of the time, gained weight during the trial, and reduced the target forage.

The San Dieguito River is a 24 mile long coastal river system located in northern San Diego County with a watershed of 345 square miles.  The Santa Fe Valley is located within the lower watershed 4 miles downstream of the Hodges Reservoir and 6.5 miles upstream of the San Dieguito Lagoon.  The Santa Fe Valley area burned in both the 2007 Witch Creek fire and 2014 Bernardo fire, following which the riparian corridor became infested with a rogue’s gallery of highly flammable invasive species including, but not limited to red gum eucalyptus (Eucalyptus camaldulensis), giant reed (Arundo donax), and acacia (Acacia sp.)  Despite this infestation, the Federally endagered least Bell’s vireo (Vireo bellii pusilus), light footed Ridgway’s rail (Rallus obsoletus levipes), and numerous other rare or sensitive species reside in patches of remaining native habitat. Beginning in 2015, our goal has been to reclaim the valley from these invasive species to improve fire safety for the surrounding communities and restore wildlife habitat values.  Through the efforts of a small group of private property owners and NGOs, a skilled team was assembled and resources procured for the ambitious task to restore 181 acres of riparian habitat within the Santa Fe Valley wresting it from tenacious invasive species and returning it to high-quality native habitat. As we approach the 10 year point we look back at the remarkable transformation that has occurred using methods from hand weeding to helicopters.

The Ventura WMA has detected, identified, and managed several early detection/rapid response (EDRR) weed species. We will discuss how these weeds were first found and reported, providing lessons for the value of communication networks in pest monitoring. We will also discuss the techniques we have used to control each of these weeds.

Addressing invasive species at the earliest stages of the invasion process – during introduction and establishment – is the most effective and resource efficient approach to management. Even so, invasive species research, management, and policy is often reactive, focusing on species that are already widespread and difficult to eradicate at scale. This is a missed opportunity to prevent harmful invasions before they have a chance to take hold, particularly as climate change drives the redistribution of biodiversity across ecosystems of the United States. In this talk, I will discuss the need for more proactive approaches to reducing invasive species introductions, particularly via the horticultural pathway, which continues to be a main vector for invasive species range infilling and range expansion. I will also discuss the evidence in support of biotic resistance, which is the idea that diverse native ecosystems can naturally resist invasive species establishment. Invasion resistance has been well supported in ecological theory and experiments, but evidence in natural systems is mixed. My work suggests this could be methodological, as a revised modeling approach shows that plant communities with high diversity are consistently less invaded, and invasion resistance varies predictably across ecosystem types and ecoregions of the United States.

The Cheadle Center for Biodiversity and Ecological Restoration has been using a combination of prescribed fire, grass-specific herbicide, hand-weeding and wildflower seeding to successfully restore portions of UCSB from invaded, non-native grasslands, to native wildflower fields. Annual wildflowers are being lost due to competition from invasive, annual grasses, and are rarely included in restoration targets. The Cheadle Center has been using prescribed fire to control rip gut brome (Bromus diandrus), since 2008, with 10 successful burns that have recovered 3.5 acres of native habitat. These burns utilize the addition of supplemental woody-fuel, to achieve high intensity fires that heat the topsoil to over 200 C, a level necessary to reduce the grass seedbank by nearly 99%. Initially, this method targeted recovering coastal sage scrub and included hand-weeding and planting. The last 5 burns have focused, instead, on recovering native wildflowers through seeding. The most recent burns have incorporated the grass-specific herbicide, Clethodim, to reduce disturbance of sensitive, germinating wildflowers and time spent hand-weeding. With over 20 wildflower species established in persistent, resilient populations that are resisting re-invasion, we know of no other similarly successful restoration strategies for recovering wildflowers in Southern California. This methodology offers a chance to restore a significant habitat type that has been largely lost in coastal California.

New species are regularly introduced into California from other parts of the world and found growing wild. Some of these spread quickly and impact native habitat, waterways, and agricultural lands and their early detection; their identification and removal could prevent impacts and save on future removal costs. Each year we select a few species that have either been newly discovered in the state or have recently expanded their range as our “Weed Alerts”. This year, Cal-IPC is joining together again with Orange County CNPS chapter invasive plant lead, Ron Vanderhoff, to showcase our selection of new and notable non-native plant species for 2025, chosen from nominations provided by regional land managers and botanists across the state and reviewed by CDFA. We will also provide an update on the Cal-IPC inventory, CDFA listing, and a few choice examples of early detection and rapid response in action.

The online WeedCUT tool, hosted by the University of California, provides best practices for controlling the approximately 300 invasive plants on Cal-IPC’s Inventory. This includes non-chemical methods, biocontrols, and herbicides. This provides an excellent resource for learning which techniques will work best on a given weed in a given situation.

Our research group at the University of California, Santa Barbara (UCSB) has been conducting large-scale restoration and associated research in the Santa Clara River (SCR) floodplain for over a decade. The goals of our program are to significantly reduce non-native, invasive giant reed (Arundo donax), re-establish resilient riparian vegetation communities, and restore ecological function/services. Giant reed is the primary stressor to riparian habitats in the SCR system, with wide-ranging impacts including excessive water use, increased wildfire risk, and degraded wildlife habitat. Over the years, we have employed a diverse array of passive and active restoration techniques to accommodate this naturally high disturbance system. The long-term nature of this program has provided opportunities for reflection and adaptation in the face of climate variability and change (prolonged droughts, increasingly intense flood events, the emergence of new invasive species, shifting species composition, etc.). This longer timeframe has also facilitated diverse partnerships and an atmosphere of trust and cooperation among stakeholders who each have their own unique goals and expectations. This presentation will share valuable insight on the challenges our restoration program has faced, adaptive management strategies that have improved project outcomes and resilience, and lessons learned that can help inform other floodplain restoration programs in California.

Invasive phragmites (Phragmites australis) has long been present in Suisun Marsh, but its spread has accelerated in the past 25 years, particularly in tidal areas where management options are restricted by sensitive endangered species habitat regulations. To address this challenge, the CA Department of Water Resources conducted a 2019–2022 pilot study, funded by the Delta Conservancy’s Prop 1 Grant Program, to evaluate the feasibility, efficacy, and environmental impacts of phragmites control at the Blacklock Restoration site. Over three years, experimental plots received mowing and herbicide treatments. Effectiveness was assessed with NDVI analysis of aerial imagery, while potential impacts were monitored through water quality sampling and herbicide detection. Results showed that treatments significantly reduced phragmites cover compared to untreated controls, and off-target impacts to water quality, food web resources, and non-target plants were well below thresholds of concern. These findings demonstrate that phragmites control in open tidal wetlands is both feasible and environmentally safe, and they provide managers with critical information to support permitting, planning, and adaptive management. Lessons from this study are guiding site-wide implementation at Blacklock (first large-scale treatment completed August 2025) and can inform restoration projects facing similar invasive species challenges across California.

In recent years, stinknet (Oncosiphon piluliferum) populations have expanded into the Coachella Valley, encroaching on habitat that many native desert annuals and perennials rely on. These annuals and perennials, in turn, create habitat and provide sustenance for a wide variety of native pollinators and herbivores. The Living Desert and the Coachella Valley Conservation Commission have been collaborating to monitor emerging populations of stinknet, eradicating them before they are able to thoroughly contaminate the soil seed bank and establish in a new location. Our efforts are focused on habitat that hosts plant species of special conservation value, such as Coachella Valley Milkvetch (Astragalus lentiginosus var. coachellae). Thus far, manual control has been sufficient for our needs. Though some populations within our management area can be numerous, they are never so numerous that herbicide application has been deemed necessary. Individual plants are marked with a single GPS point, as are large populations (>20 individuals). This data is then compiled in ArcGIS and referenced to monitor the year-to-year spread or lack thereof. Permitting, both for land access and for herbicide use, has been unnecessary thus far. Prevention is always less expensive than mitigation as far as stinknet is concerned.

Habitat conversion to invasive plant dominance, has become a ubiquitous problem globally. In areas where degradation and conversion have already occurred, ecological restoration–the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed–provides a promising avenue to restore and conserve biodiversity and ecosystem functions. Influenced by competition and niche partitioning theory, single species plantation and/or random style planting has been the restoration status quo for decades. Renewed focus on plant facilitation, however, has led to the introduction of promising new techniques. One such technique is the idea of planting restoration islands that can act as spreading nuclei for native species. Here, we test this approach in a southern California shrubland restoration experiment the goal of which is to improve methods for woody species re-establishment in a harsh Mediterranean environment. We find that there is a consistent positive influence of higher planting density on seedling survival particularly for sage scrub (as opposed to chaparral) species. Additionally, we find that by year 2, plots planted at higher density have exerted more of a plot-level influence on reducing invasive species cover and increasing native seedling recruitment. These findings suggest that future restoration efforts in southern California shrublands might have more success if they adopt a restoration island approach.

As the Contra Costa County IPM Coordinator, I am committed to ensuring that our WMA is well trained on IPM methodology. Our communities are concerned with environmental health, and our weed management practices need to be exemplary. I will discuss the IPM education we are including in our operations. The implications for effective weed management of a once defunct WMA being led by a Resource Conservation District (RCD) will be discussed- including strategic IPM plans.

We will provide a status update on WMA contracts and the requirements for MOUs, strategic plans, reporting, mapping, and permitting. We will discuss the role of the WMA Oversight Committee and the grants for WMA invasive plant management support activities. We will share the latest information on pest risk assessments for plants and the Noxious Weed List.

Irvine Ranch Conservancy practices seed-based restoration on large-scale projects. This requires that the weed seedbank be largely depleted prior to seeding. We are using Esplanade (Indaziflam) as an alternative to glyphosate for site preparation. Esplanade is a long-lasting, broad spectrum, pre-emergent herbicide that is applied at extremely low rates. Esplanade can be successfully used for site preparation of highly-degraded habitats with long-lived weed seedbanks. It requires precise and even application but a single application is generally sufficient. It has residual effects in the soil that last for at least three years in southern California. Seeding may be done two years after herbicide application but some sensitive species will be affected. We will share experiences, observations, and lessons learned in using this herbicide on over 40 acres at the Bommer Canyon Preserve in the City of Irvine.

In October 2017, the Tubbs Fire burned through 90% of Pepperwood’s 3,200-acre biological field station. In October of 2019, the Kincade Fire reburned 60% of the preserve. Each of these fires presented unique challenges and opportunities. Here, we share our observations on how invasive plant distributions and abundances differed each year following the Tubbs Fire, and outline some differences and our expectations for how invasive plants will respond to the Kincade wildfire along with the actions we are taking. In general, the wildfires have given us an advantage controlling some invasive plant species such as Himalayan blackberry (Rubus armeniacus) and Barbed goatgrass (Aegilops triuncialis), while increasing the spread and productivity of others such as Stinkwort (Dittrichia graveolens), French Broom (Genista monspessulana), Oblong Spurge (Euphorbia oblongata), and Bull thistle (Cirsium vulgare).

Several bushes of sweet hakea (Hakea drupacea), an Australian shrub in the Protea family, were discovered and removed from Julia Pfeiffer Burns State Park last year! Also in our Big Sur Sector, we found the first deteciton of false hawkbit (Urospermum picroides) in 2025. These are 2 examples of the many new and novel weeds we’re finding in California State Parks. The Department has had an ongoing weed management program for decades. However, our statewide EDRR program is fairly new. Since providing EDRR training to our district staff from 2021-2023, our EDRR surveys have been yielding many new invasive species detections. Most are widespread elsewhere but only recent arrivals locally, like petite licorice (Helichrysum petiolare) discovered in Van Damme State Park in Mendocino County last year. Others are escaped ornamentals from nearby urban ares, such as firethorns (Pyracantha sp.) and Chinse tallow (Triadica sebifera) at Folsom Lake State Recreation Area. In our historic parks, some come with the added complication of whether they have cultural significance giving them protected status, such as tree of heaven (Ailanthus altissima) in Marshall Gold Discovery State Historic Park. A quick initial review of State Parks and our invasive species management will lead into specific examples of new and novel weeds across California. Many will be familiar to the audience already controlling the same species, but some may be surprising.

The San Diego County Dept. of Agriculture, the lead for the San Diego WMA, conducts management efforts (with the help of many SDWMA partners) through hand pulling and/or herbicide application (with a select set of materials) on 18 regional priority weed species each year. This implements EDRR work based on regional prioritization plan that ranked invasive plant species into five categories, based in a large part on their impact to listed species as well as target plant distribution/abundance. The regional plan was developed and significant funding applied toward EDRR work from the San Diego Association of Governments for the purposes of protecting listed species (NSCP/MHCP). Detailed GIS based tracking efforts over the last five years show 136 active populations and 25 eradicated populations of species in the top categories. Outreach ID flyers, an engaged land management and naturalist community increase the chances that new populations will be reported on iNaturalist and Calflora.

The Geology Fire occurred in June 2023 in Pleasant Valley in Joshua Tree National Park, igniting a fuel bed of invasive grasses that spread 1033 acres through Mojave mixed shrublands and Joshua tree woodlands. Fire suppression was aggressive with immediate direct attack allowing fire engines off-road travel and fire retardant dropped from aircraft to achieve containment. Phosphorus-based fire retardant is an effective tool for fire suppression but can act as a plant fertilizer and can result in increased abundance of invasive annual grasses, such as Mediterranean grass (Schismus spp). However, wildland fire itself is also a major contributor to invasive grass abundance through the grass-fire cycle. It is therefore critical for land managers who want to manage for invasive grasses to understand the magnitude and spatial scale of effects of both retardant and wildfire. We measured Mediterranean grass cover and density ten months and twenty-two months after the fire in parallel unburned, retardant-impacted, and burned transects along the perimeter of the Geology Fire. In the first year following the fire, density and cover of Mediterranean grass post-fire was elevated in both the burned and retardant drop areas. The use of fire retardant did not stimulate a Mediterranean grass increase beyond that observed in burned areas. Minimizing acreage burned was beneficial to this non-fire adapted mid-elevation Mojave Desert vegetation community.

Invasive plants with large floral displays may alter the frequency and effectiveness of animal pollination of native plants. Invasive plants can 1) compete for pollinators and reduce the visitation rates of native plants, 2) increase the likelihood of clogging the stigmas with the wrong pollen and 3) decrease the local density of conspecific native flowers reducing the ability to attract pollinators. We implemented a field experiment to understand the impacts of French broom (Genista monspessulana) on pollination and reproductive success of 7 remnant native forbs in 3 California grasslands in the Santa Cruz Mountains. French broom is a bee pollinated shrub that produces large floral displays. Pollination and reproductive success of native plants are more likely to be impacted by the presence of French broom if they share pollinators with the invader. We observed pollinator visitation on French broom and the native forbs and found a substantial degree of pollinator differentiation between the native forbs and the invader. French broom pollination was dominated by European honeybees and the native forbs were pollinated by bumble bees and other native pollinators. Then we measured pollen limitation and fruit set of native forbs growing in either the presence or absence of French broom. Contrary to our predictions, French broom did not reduce pollinator visits or reproductive success of the native forbs. 

Montane forests are restricted to “sky islands” of mountain habitat in the Transverse and Peninsular mountain ranges of Southern California. Significant areas are being progressively impacted by severe disturbance cycles that increase forest vulnerability to invasive species. These relatively small forests protect the upper watersheds of all of the region’s major rivers and provide a high number of ecosystem services, including carbon sequestration, soil conservation, erosion and sedimentation reduction, provision of plant and wildlife habitat and migration corridors, recreational opportunities, and about 40% of the water used for human, agricultural, and industrial purposes in southern California. Proactive management focused on forest health must focus on forest retention through adaptation and building resilience. Through the Southern Montane Forest Project, scientists and managers co-produced a conservation strategy with region-specific guidance and resources for managers across land ownerships. The strategy is a roadmap for prioritizing treatments across landscapes, incorporating adaptation science into projects, and supporting postfire recovery, with management of invasive species integrated throughout. Highlights include an innovative “Adaptation Menu” that summarizes management tactics for unburned and burned forest. This talk will provide a tour of the invasive-focused aspects of the montane forest conservation strategy.

General categories and types of pesticide adjuvants and their common active ingredients. How to decipher the adjuvant label including signal words. Laws and regulations specific to pesticide adjuvants including updates to updates relating to adjuvants in the National Pollutant Discharge Elimination System General. How adjuvants can enhance herbicide efficacy and use rates. Which adjuvants are appropriate based on target species, environmental conditions and tank mixtures with human and environmental risk from adjuvant active ingredients in mind. Best choices to avoid pesticide drift impacts.

Esri provides out-of-the-box Geographic Information Systems (GIS) software that can be used to create workflows for mapping weeds. In the San Francisco Estuary, these workflows are being used by Cal-IPC projects to map and inform management of invasive cordgrass (Spartina spp.), sea lavendar (Limonium spp.), and seashore Paspalum (P. vaginatum). I will discuss how workflows and GIS datasets have been adapted to meet the unique needs of each project using Esri Field Maps, ArcGIS Pro, ArcGIS Enterprise, and ArcGIS Online. I will demonstrate some of the customizations employed to maximize efficiency in the field and in the office. This presentation may be useful to those who are interested in weed mapping with the goal of informing multi-year weed control efforts.

County Weed Management Areas (WMAs) contribute to effective weed management in several ways: sharing IPM best practices among local land managers for how to best control particular weed species; ensuring jurisdictional cooperation among land managers so that weed populations are fully managed when they cross property lines; setting landscape-level priorities for target invasive plant species based on their impact and threat to spread; communicating about new sightings and early detections of invasive plants to enable rapid response. Lessons learned from WMAs will be shared for the benefit of other WMAs seeking to strengthen land manager effectiveness in managing invasive species in their area.

Laguna Canyon Foundation has been engaged in habitat restoration, fuel modification and targeted invasive control projects covering hundreds of acres in and around Laguna Beach, CA since 2012. The careful use of synthetic herbicides as part of an integrated pest management program has been an important component of this work. Over the past several years, concern over and resistance to the use of synthetic herbicides, especially glyphosate, has grown steadily. This presentation will build on last year’s presentation to address additional types of challenges we’ve encountered, how we’ve addressed them and recommendations for other land managers who might face similar challenges.

Restoration practitioners work to restore native communities that fill available niches, assembling a strong biotic filter to prevent invasion by invasive species. One challenge is that abiotic disturbances, such as severe drought, flooding, and wildfire, can impact restored communities and allow for future invasions. This challenge is exacerbated by the likelihood that non-native, invasive species are already present in the seed bank of restored communities. My research group conducted several restoration experiments to test methods of increasing resistance. We have worked to restore resistant communities by manipulating: (1) functional traits of natives added to the site; (2) native seed sources; and (3) abiotic conditions. We found that all manipulations significantly altered community resistance, although not always in the expected direction. For example, native plant functional traits prevented invasion in high-resource environments, but not in lower-resource environments. Natives sourced from sites with higher temperatures were more resistant to drought for some species and less resistant for others. Increased abiotic variation due to climate change continues to increase the intensity and duration of disturbances. Incorporating increased diversity of natives, both within and amongst species, may improve outcomes, yet continued removal of invasive species is likely necessary.

On Santa Cruz Island, a series of land use practices starting in the 1850s led to near ecosystem collapse. Ranching, agriculture, invasive species, and biocontrol agents have all played significant roles in altering the island’s fragile and unique ecosystem. Conservation entities began a 50-year effort of complex protection and conservation interventions in the 1970s, which resulted in difficult tradeoffs. Serving as a living laboratory, several conservation strategies and tools that are used commonly today throughout the world were tested and developed on Santa Cruz Island, with others currently being tested. Thirty-four invasive plant species were targeted for eradication. Survey and detection methods for incipient populations were developed to support island-wide invasive plant treatments. The island is on a strong trajectory of recovery with native dominated vegetation communities, three species recently removed from the Endangered Species List, and other Channel Islands’ endemic plant species recovered there. However, as novel threats loom, it begs the question- what is recovery?

Herbicides are a critical tool for controlling aggressive invasive species, especially during large-scale restoration efforts, but their persistence in soils can hinder the establishment and success of desirable vegetation. Imazapyr is a commonly used herbicide to control highly aggressive species, such as Arundo donax, with a reported soil residence time ranging from three to twelve months. However, we observed herbicide damage on foundational tree species (Salix and Populus) installed from cuttings more than two years after imazapyr was applied to control expansive A. donax monocultures as part of a large-scale riparian forest restoration project. Individuals from all tree species exhibited signs of herbicide damage, and the height of damaged individuals was significantly lower than that of healthy trees. However, the percentage of trees damaged and the extent to which herbicide damage stunted tree growth differed significantly among species. Faster growing species, such S. laevigata and P. trichocarpa, were more likely to exhibit herbicide damage and more pronounced reductions in growth compared to P. fremontii and P. trichocarpa x fremontii hybrids. Despite these lingering, previously undocumented negative impacts, imazapyr is still one of the most effective treatment options for some aggressive invaders. Thus, practitioners should be aware of the potential long-term effects of imazapyr and carefully consider species selection and planting schedule during revegetation.

In arid lands, where plant abundance varies yearly with precipitation, it is critical to refine approaches on how plant invader impacts are assessed. Invader abundance, which is often used to gauge invader impact, can exhibit cyclical boom-bust patterns in arid lands, making it difficult to track invader impact. In this study, we analyzed a 17-year plant monitoring data set to evaluate the boom-bust dynamics of the invader Sahara mustard (Brassica tournefortii) in a stable sand dune community. We identified that the frequency of Brassica booms and the magnitude of these booms led to changes in plant communities. We found that increasing the mean magnitude of an invader boom led to a decrease in the asynchrony of species within the community and to the stability of the overall plant community. Increasing boom frequency also decreased stability but less strongly. Lastly, the mean magnitude of Brassica booms shifted the relationship between community synchrony and stability, where the negative relationship that occurs in uninvaded communities became shallower with increasing boom abundance, suggesting that the asynchrony in species abundances that often confers stability within semi-arid and arid communities is being lost with high invasion. Our research highlights the application of a new invasion regime framework to capture invader impacts in a temporally variable system. This knowledge can guide decision making to more effectively mitigate the impact of invasive species.

Historically invaded ecosystems that continue to support native biodiversity are ideal places to explore plant community dynamics as we look ahead to mediate future climate change and invasion impacts. The Carrizo Plain National Monument (CPNM), CA, is an intact representative of the San Joaquin Desert ecosystem and is home to a wide array of threatened and endangered plant and animal species. Invasive species, primarily non-native grasses such as Bromus rubens and Hordeum murinum, are persistent here and mediating their impacts is of utmost concern to the conservation of this sensitive ecosystem. The dynamics of CPNM are closely tied to patterns of interannual precipitation and the ecosystem engineering impacts of the giant kangaroo rat (GKR, Dipodomys ingens). Within these semi-arid grasslands we ask: what are the effects of water availability and rodent pressure on plant community dynamics? We manipulated water availability to represent drought (50%), ambient (100%), and abundant (150%) rainfall in the presence or absence of GKR from 2015-2021 and measured plant community composition annually. We found that GKR maintained plant biodiversity across our precipitation regimes. Further, where GKR are present, cover of native and non-native species follow similar trends over time; conversely, where GKR are absent, non-native cover becomes dominant. Taken together, these results provide important context for management of invasive grasses in this ecosystem.

California’s native needlegrass grasslands are highly imperiled due to habitat loss, invasive species, and altered disturbance regimes. In Orange County, these ecosystems are under-surveyed and poorly mapped, limiting effective restoration planning. This study combines field surveys and species distribution modeling to assess the distribution, condition, and restoration potential of needlegrass grasslands within the Southern Subregion of OC Parks. Field surveys in Caspers Wilderness Park and Audubon Starr Ranch identified high-cover needlegrass patches, refined existing vegetation maps, and documented native and invasive species. A total of 46 qualifying presence points were used to generate a MaxEnt habitat suitability model, with strong performance metrics (AUC = 0.95; TSS = 0.84). Key environmental predictors included elevation, soil texture, aspect, and slope. Project outputs include an updated inventory of needlegrass grasslands, a targeted invasive species management map, a native species list for restoration planning, and a suitability map to guide future restoration. Findings suggest Stipa pulchra occupies a range of landscape settings, and that high-suitability areas not currently dominated by native grasses may be strong candidates for restoration. This project provides a practical approach for land managers in the Orange County region.

Our WMA has a complex jurisdictional structure over a complex geographic area. In order to be effective at controlling the spread of invasive plants, we have dedicated time to developing a strategic plan, which is required by CDFA of each WMA, and includes an IPM approach. Our plan includes information on priority weeds in our area and how to best control them. This provides a reference for local land managers to make sure they are using the preferred IPM approach. Our plan also describes the educational elements our WMA will implement to train local land managers and share key information about new weeds.

Understanding licenses required for pesticide use including who needs a license, the different types of DPR licenses/certifications, and handler training. An overview of pesticide use reporting covering who is required to report pesticide use, how and when to report pesticide use. Pesticide use recommendations: what they are, when they are required, and who can issue a recommendation. Pesticide handler training requirements. Managing off-target herbicide contamination from drift and water contamination. Understanding label requirements for common herbicides including PPE, rates, and special cases.

While comprehensive early detection rapid response (EDRR) programs are the ideal way to find and manage new invasions, they can also take years to develop and require resources beyond what many organizations have. Yet opportunistically spotting new populations of unfamiliar species and managing them can still have landscape-level benefits. Detecting new weeds is a learnable skill, and preparation can maximize the odds of spotting something new – and possibly eradicating it – before it becomes widespread. Informal early detection efforts by Valley Water technical staff and crew have resulted in the eradication of several species very early on the invasion curve in riparian Santa Clara County, including skeletonweed (Chondrilla juncea), stinknet (Oncosiphon pilulifer), and cobra lily (Chasmanthe floribunda). Some of these eradication efforts were as minor and quick as the removal of a single plant prior to seeding. Without formal botanical training, crew members have been instrumental in contributing new sightings. This talk covers the preparation and skills needed to spot new species in the wild, where to look for them, and resources to help with ID and management. Even without a formal EDRR program, land managers can find and stop new weeds before they become a landscape-level problem.

The Southern California Ignition Reduction Program is a globally significant, innovative initiative to address the heart of our wildfire problem: far too many fires. 95% of these are human-caused, and two-thirds occur along roadways and are concentrated where ignitable invasive species, especially annual grasses, are abundant. While education, enforcement, and engineering solutions are important, the vegetation management need is immense. For the past few years, we have been building the tools we need to address this problem. We mapped the abundance of invasive plants along 850 miles of roadways. We commissioned the Durable Ignition Reduction Toolbox through Cal IPC to guide control method selection depending on starting and desired conditions. We collected the seeds of less ignitable native plants and have been bulking that seed to replace the invasive plants. We have built organizational structures to work together across ownership boundaries. We have completed demonstration projects for the methods. We will have just completed environmental compliance documents for 3 pilot roadways: I-8 through San Diego County, Highway 74 between Orange and Riverside Counties, and I-15 and Highways 18 and 138 in San Bernardino County. And large-scale treatments are beginning at the time of the meeting! All of this work continues to grow at the intersection of invasive plants, wildfire, restoration, and science through partnership, and more partners are always welcome.

With an increase in frequency and severity of wildfires across California, many oak woodlands have seen notable degradation in vegetation community composition following wildfires. Blue oak (Quercus douglasii) woodlands are the most abundant oak woodland species type in California. Prescribed fire, implemented in fall and winter, has been used across blue oak woodland ecosystems to promote native species diversity and reduce catastrophic wildfire risk. This research examines the influence of pre-wildfire prescribed fire treatments on native and non-native understory species establishment after the 2024 Park Fire on the Big Chico Creek Ecological Reserve (BCCER). Prior to the Park Fire, surveys showed native species presence was greater than non-native presence in both pre-wildfire prescribed fire treated (53%, SD = 18%) and untreated (62%, SD = 21%) plots. Additionally, Cal-IPC high and moderate rated invasive species, comprised of non-native grasses, wild oats (Avena spp.), foxtail brome (Bromus madritensis ssp. rubens), and ripgut brome (Bromus diandrus), had greater cover in the pre-wildfire prescribed fire treated plots (30%, SD = 17%) compared with the plots without pre-wildfire prescribed fire treatments (25%, SD = 19%). Late summer timing of the Park Fire is predicted to positively influence non-native and invasive species abundance in the years following the wildfire.

Wildflowers are declining under nutrient deposition, large mammalian herbivore loss, and invasive plant species, raising questions about impacts on pollinators. In three California grasslands, we tested whether invasive wildflowers species could compensate pollinators for losses in native wildflowers under nutrient addition and large mammalian herbivore exclusion. We crossed the addition of phosphorus, nitrogen, and potassium nutrients with herbivore exclusion fences in randomized, multifactorial experiments located at the University of California McLaughlin Reserve, Hopland Extension Center, and Sierra Foothills Extension Center, collecting data on flower abundance and pollinator visitation. Invasive wildflower species provided pollinators with substitute food resources in cases where nutrient addition and herbivore exclusion depleted native wildflower resources. Invasive thistles (Centaurea solstitialis, Carduus pycnocephalus) acted as core hubs for both generalist and specialist pollinators. However, increases in invasive wildflower abundances under nutrient additions increased visits by the non-native pollinators western honeybee (Apis mellifera) and leaf-cutter bee (Megachile apicalis), suggesting possible invasional meltdowns. These findings pose a management paradox: invasive wildflowers, despite their broader negative ecological impacts, can support pollinators. Combining invasive wildflower removal with native wildflower restoration will help address this paradox.

Stinkwort (Dittrichea graveloens), a high priority invasive plant, was discovered for the first time on the Irvine Ranch Conservancy’s managed lands in 2023. Staff and volunteers deployed to survey the extent of the population in Santiago and Silverado creeks that same year. Survey and control efforts have been thorough and consistent ever since and we have seen fewer plants each year in those populations. While the overall footprint of the population ended up being quite large (over 2.5 miles of creek), the total number of plants discovered was relatively low, suggesting a recent intorduction in the watershed. While we are not restricted in our use of herbicide for this project, a non-chemical approach (hand pulling) has been employed for this project. The efforts of IRC volunteers have also been key to the success of this project.

For the last several years, The Palos Verdes Peninsula Land Conservancy has been converting large groves of invasive fuel loads into habitat for several threatened and endangered species. We’ve used various methods including cut stump treatments, strategic mowing, and grazing to remove species like Acacia (Acacia Cyclops), Black Mustard (Brassica nigra), and other invasive species that can become dangerous fuel loads. Removal of these invasive species provides an opportunity to restore and preserve native coastal sage scrub (CSS) habitat for the conservation of the Palos Verdes Blue butterfly (PVB), El Segundo Blue butterfly (ESB), coastal Cactus Wren, and California Gnatcatcher. The PVB was thought to be extinct and thanks to these projects, the butterfly is now being reintroduced into these habitats we’ve created. Over 250 acres of invasive species have been removed and CSS restored. This presentation will show the impacts of not just large restoration projects but also small scale multi-benefit checkerboard projects.

The Living Desert Zoo and Gardens is working to restore desert pupfish in the Salt Creek watershed, near the Salton Sea. A declining water supply and invasive tamarisk have harmed their habitat. The Bureau of Land Management has cleared out tamarisk and brought back native plants. This allows more sunlight to enter and increases water availability, which benefits pupfish populations. The tamarisk leaf beetle has also contributed to the reduction of tamarisk. However, tamarisk still covers the middle part of Salt Creek. The next phase of these efforts focuses on the middle section of the creek, involving a thorough removal of invasive tamarisk plants and the concurrent reintroduction of native vegetation. This thoughtful strategy not only reduces the excessive shading caused by tamarisk but also revitalizes the stream flow, creating a more dynamic and inviting aquatic environment. As a result, the habitat for the endangered pupfish has expanded significantly. By emphasizing active management and ecological restoration, this approach effectively reverses the trends of habitat degradation. It fosters resilient native ecosystems while significantly bolstering the long-term viability of pupfish populations in the Salt Creek region. Although great progress has been made, some important lessons related to the long-term resilience of Salt Creek have been learned. The future stability of this pupfish habitat will require the targeted restoration of hydrology and creek geomorphology.

The Guadalupe-Nipomo Dunes National Wildlife Refuge is located within the Guadalupe Nipomo Dunes Complex of San Luis Obispo and Santa Barbara Counties. It is home to diverse coastal dune ecosystems with federal and state-listed species which are threatened by the expansion of aggressive invasive plant species. The Land Conservancy of San Luis Obispo County, a county-wide land trust, has worked with the Federal Wildlife Refuge to remove invasive species threats from the coastal foredune habitat in order to protect and enhance rare plant species and nesting habitat for Western snowy plover (Charadrius nivosus nivosus). Creative solutions are necessary to manage invasive species surrounding listed species in this unique coastal dune habitat. Both chemical (backpack, truck sprayer) and mechanical invasive species removal methods are used with special attention to seasonality. As high priority invasive species are eliminated, new secondary invaders fill their niche. Long-term management strategies through property and regional management plans are essential to recovering rare species and preserving unique coastal ecosystems.

Iceplant (Carpobrotus edulis) is a prolific invader in coastal habitats with Mediterranean type climates across the globe. Where it invades, it often displaces native plants and alters ecosystem processes. Consequently, ecological restoration of these iceplant-invaded landscapes is a critical goal for many coastal land management agencies. At the Jack and Laura Dangermond Preserve (TNC), a complex study encompassing 30 acres of iceplant removal and restoration was designed to better understand the effectiveness of tools and techniques practitioners have used to restore iceplant-dominated areas. Key goals include: (1) minimizing secondary invasions after iceplant control, (2) maximizing native plant establishment and (3) reducing iceplant reinvasion. To achieve these goals, we tested methods to: (a) manage secondary invaders and re-invading iceplant, (b) manage dead iceplant material after initial kill, and (c) evaluate the most cost-effective way to get native plants established. The experiments were conducted in wetland, dune, and scrub environments. Our findings suggest wide spectrum herbicide (2% glyphosate), is more effective at minimizing secondary invasions and/or iceplant reinvasion than specialized ones (2% clethodim or 2% triclopyr choline). Establishment of native plant species from seeds is highly effective in scrub habitats while reliance on preexisting seedbanks and intact native vegetation in dune and wetland habitats is sufficient for recovery.

The Ojai Valley Land Conservancy (OVLC) is leading a watershed effort to eradicate invasive Arundo or giant reed (Arundo donax), treat a wide range of invasive and non-native species, and restore the riparian corridors – the Ventura River Watershed Riparian Resilience Program. Arundo is an aggressive invasive grass that infests and can dominate riparian ecosystems across California, displacing critical habitat home to a number of rare and listed species. The VRW Program details a programmatic approach to restoration that is tailored to local watershed priorities, focused on Arundo with guidance broader for practical implementation, and adaptable for increasingly stochastic conditions in a changing climate. This program may be used as a model to accelerate the pace and scale of riparian restoration for watersheds across California, filling a gap for land managers navigating complicated permit pathways. OVLC has partnered with the Ventura County Resource Conservation District as CEQA lead agency for the Ventura River Watershed Riparian Resilience Program, which received the first programmatic, watershed-scale Statutory Exemption for Restoration Projects (SERP) in the State. This presentation will discuss development, funding, permitting, outreach, implementation, treatment methods, and monitoring for our program, and lessons learned for applications in other watersheds.

Although invasive plants are a major topic of ecological research, and have had management developed and refined for decades, this aspect of fungal biology is lagging remarkably far behind. Although there are a few famous examples of invasive fungi (for example the Death Cap, Amanita phalloides) a comprehensive working list of the non-native fungi present in California was first assembled only in the past year. We’ll discuss the main groups and life history profiles of invasive fungi, link their ecology to co-invasion with plants, and talk about management strategies focused on rare fungi and the threats they face from invasive species across kingdoms.

Native bee diversity is declining in California and across the globe. Invasion by non-native plant species is a key contributor to these declines through replacement and loss of native cover, which decreases overall plant diversity as well as the floral and nesting resources that native plants provide. This is especially acute for specialist bee species that rely on one or a few native plant species. Habitat restoration, specifically reducing invasive plant cover and increasing the diversity and abundance of native plants, repairs ecosystem function and increases vital resources for native bees. Since 2022, we have been assessing how bee diversity and functional group composition are responding to active restoration of diverse riparian habitat at a 285-acre agricultural property along the Santa Clara River, as well as at intact riparian habitats along the river. This presentation will explain the results of this study as they relate to relative cover of invasive and native plants, bee composition response to restoration, and bee communities associated with southern California riparian forest and scrub vegetation. We will also provide recommendations for selecting native plants and improving habitat to benefit native bee populations as part of restoration projects.

Airborne imaging spectroscopy combined with machine learning methods have proven valuable for detecting invasive plant species. With the emergence of open source spaceborne imaging spectroscopy, biweekly global coverage of imaging spectroscopy data will soon become available, albeit at lower spatial resolution compared to airborne systems. To prepare for the use of these data in active management solutions, it is imperative to understand how model performance is affected by spatial resolution and how prediction accuracy varies across large geographic extents. We used high spatial resolution (2 m) airborne imaging spectroscopy data from the Global Airborne Observatory (GAO) to model native and invasive plant distributions and evaluate model accuracy across diverse, heterogeneous ecoregions in Southern California. We also applied several supervised and unsupervised modeling methods to evaluate which approach effectively detects invasive plants at the subpixel level using Airborne Visible InfraRed Imaging Spectrometer (AVIRIS) data at 15 m and 30 m spatial resolutions in alignment with current and upcoming spaceborne imaging spectroscopy missions.

California’s oak woodlands face a compounding crisis from altered fire regimes, and the devastating Goldspotted Oak Borer (GSOB, Agrilus auroguttatus). Moving beyond single-issue management, our work presents a community-based model that weaves Traditional Ecological Knowledge with capacity building and Western science to foster holistic ecosystem resilience. This presentation details two integrated, non-chemical management strategies. First, to mitigate GSOB impacts and improve recovery, our methods include landscape-level monitoring, strategic removal of infested trees, and sanitation of wood materials to disrupt the beetle’s life cycle and reduce hazardous fuels. Second, in partnership with Indigenous cultural fire practitioners, we are reintroducing low-severity cultural burns to the landscape. This practice serves to reduce tree density and modify fuel structures which create conditions favorable for native understory flora, and revitalize human-ecological relationships. Our results demonstrate a powerful synergy: GSOB management prompting safer conditions for cultural burns, while the reintroduction of fire improves overall forest health, thereby building the system’s resistance to future invasion and its resilience to pests and drought. This integrated approach offers a transferable framework for moving beyond eradication toward long-term resistance, resilience, and recovery.

We conducted a prescribed burn in a coastal sage scrub site characterized by pockets of native shrubs and gaps between shrubs, which were dominated by nonnative grasses. We investigated whether high-intensity fire could shift the whole site toward a native-dominated plant community, or whether the habitat heterogeneity would affect fire behavior and post-fire communities. We also treated soil seed bank samples to charate and heat to test whether these isolated fire attributes were drivers of post-fire plant assemblages. We found that fire temperatures under shrubs were hotter than that in the gaps between shrubs, but this difference did not correlate with a difference in post-fire plant assemblages, either in the field or in seed bank germination tests. The lab charate and heat treatments also did not have an effect on seedling composition in seed bank germination tests. In addition, seedling species richness did not significantly differ between seed bank samples taken before and after the fire, although some invasive bromes (Bromus spp.) were less abundant in post-fire samples and brome fescue (Festuca bromoides) only germinated in post-fire samples. These results indicate that post-fire plant assemblages are primarily driven by the soil seed bank, suggesting that fire is most useful as a restoration tool if the seed bank is dominated by native species. In our study site, the presence of nonnative species in the seed bank requires additional invasive species management.

Site hygiene is not known for being the most compelling topic, especially for early-career professionals who may just be learning about the impacts of weeds on ecosystems. However, it’s a practice that can make a huge difference, especially for groups like Conservation Corps that are often doing front-line weed and fuels-removal work. To inject some pizzazz and mild surrealism into what can sometimes be a very dry subject, Cal-IPC partnered with Civicorps and Hip Hop for Change in 2023 to create a short music video with the help of five Corpsmembers and a $5,000 grant from the Alameda County Fish and Wildlife Commission. Over the course of two work days, Corpsmembers got a crash course in Hip Hop history, beatmaking, what site hygiene is, and why it matters. Lyrics were written, takes were recorded, a video was born. Since then, the video has been used as a supplemental site hygiene training tool for numerous Corpsmembers and has gotten a lot of positive feedback. Using this pop culture medium has proved to be an entertaining and engaging way to capture the attention of Corpsmembers and help site hygiene practices become a little more memorable.

Another important resource is Calflora, where you can track treatment of EDRR weed populations using history stacks. We will go over how to make the best use of these tools for monitoring invasive species populations.

In California’s endangered coastal sage scrub, many native wildflowers persist belowground as seeds or bulbs, emerging only after wildfire. Although adapted to survive prolonged unfavorable conditions, these species are increasingly threatened by nonnative plant invasion and environmental change. Nitrogen (N) deposition is a known driver of biodiversity loss, yet its effects on fire-following species remain unclear. We evaluated the impact of N deposition on post-fire recovery in coastal sage scrub in southern California using plots that received four levels of N addition. N addition suppressed native forbs and increased nonnative abundance in the first years post-fire. Six functionally diverse native forbs were especially sensitive to elevated N, while Bromus rubens and Hirschfeldia incana increased with N addition. These results highlight how invasion and N deposition can hamper post-fire recovery and deplete cryptic plant diversity in fire-prone ecosystems through the suppression of fleeting, post-fire bloom events. If native wildflowers fail to replenish the soil seed bank, and native shrubs fail to establish, this may lead to the conversion of coastal scrub to invasive-dominated grasslands. Strategic post-fire weed management is therefore critical for protecting these sensitive species and ecosystems.

In 2015 CIR was given a grant from the National Fish and Wildlife Foundation to remove tamarisk (Tamarix ramosissima). Over 10 years we completed 5 grants with 4 amendments to work in the Santa Ynez, Sisquoc and lower Piru Creek watersheds in the Los Padres National Forest. We worked closely with the Forest Service and took volunteers on work trips that gave community participation and provided a 30% match to our grant. It was a vast work area, covering over 1500 square miles. Though not every inch of that was walked, the rivers and tributaries were. Using mule support for many trips, the team carried out tamarisk survey and treatment, with chemical and hand tools, including large mature trees, meadows of regrowth after fire or flood and saplings propagating downstream. In response to the access we lost after the winter storms of 2023, we created three sub-projects, described as “Post Storm Treatment”. This was to work in the front country and included removal of yellow star thistle (Centaurea solstitialis), fennel (Foeniculum vulgare), Spanish broom (Spartium junceum) and purple veldt grass (Ehrharta calycina), which were all of high concern to the Forest. With the support of NFWF and LPNF we were given the opportunity for success which was met on all levels. We surmounted the challenges of trying to work across various jurisdictional lines which we did, and it was a positive experience for those involved, and the parties are trying to find ways to keep this work going.

For water-thirsty invasive plants, an important benefit of eradication is water savings through reduced evapotranspiration (ET), leading to increased surface water availability and groundwater recharge. However, measuring plant water use is difficult, sometimes leading to widely different estimates for a given species. Regional climate and other factors can influence ET, making locally-collected data important in assessing water use of a particular population. The RCD of Monterey County used an open access platform – OpenET – to quantify water savings of our Salinas River Arundo Eradication Program. OpenET uses remotely sensed satellite data, meteorological data, and reference ET from standardized stations to calculate ET at ¼ acre per pixel at up to daily time steps. We compared ET rates from untreated and treated arundo (Arundo donax), riparian trees, and herbaceous vegetation in the Salinas River by pulling monthly ET data from the OpenET API for each vegetation type from 2009-2023. We documented a substantial decrease in ET after arundo was treated and estimated a water savings of 21.1 (+/- 3.0) inches per year per area of removed arundo, accounting for replacement vegetation. For our whole program to-date, this represents a cumulative estimated water savings of 1856 acre-feet per year. We conclude that OpenET is a useful tool for assessing water savings benefits of invasive plant control and could be applied to other projects throughout California.

Invasive plants drive biodiversity loss and have enormous economic and ecological impacts in California. Key interactions involving invasive plants concern those with co-evolved herbivores introduced for biological control. To date, there are few studies quantifying the influence of a rapidly growing anthropogenic stressor, artificial light at night (ALAN), on non-native invasive plant species and their associated herbivores, and none on invasive plant biological control agents. Experiments assessing the effects of ALAN have revealed that it can have significant impacts on insects and their host plants. We investigated the potential effects of ALAN on a prolific, established invasive plant, yellow star-thistle (Centaurea solstitialis), and its biological control agents, while controlling for other environmental variables. In particular, we assessed how ALAN influences host colonization and density of biocontrol agents on yellow star-thistle. Preliminary results indicate that ALAN does not have a significant effect on the probability of insect damage or on insect densities on plants. We suspect that this is because ALAN has minimal or no effects on insects that develop within opaque plant tissues, like yellow star thistle seed heads. The role of ALAN in other biological control systems remains unexplored but may have differing effects depending on the life history of the biocontrol agents and, in particular, on the extent to which agents are exposed to ALAN during development.

Public Gardens as Sentinels against Invasive Plants (PGSIP) provides a standardized framework for gardens to submit observations of non-native plant taxa escaping from cultivation. Each observation is recorded and ranked according to PGSIP guidelines. Currently 60 gardens are participating in PGSIP across North America and over 1,000 plant records have been submitted to the database. A key value of PGSIP lies in records that are ranked “Watchlist” or “Potentially Invasive”. These species are either not on the radar of authorities or there is conflicting information about their invasiveness. As the database has grown, the PGSIP Working Group has been sharing data trends with many stakeholder groups including state regulatory authorities and green industry stakeholders. This presentation will share several PGSIP resources including: new Plant Alerts that increase awareness of priority species and recommend actions to monitor these plants and limit their spread, a publicly available Data Dashboard that shares real time information on the most commonly recorded taxa, and scientific publications from the PGSIP Working Group that analyze the collected data, highlighting species of concern and discuss how the observations of gardens compare to species that are of concern at the state level. PGSIP data can inform policy decisions at public gardens, improve plant risk assessments, and guide propagation research and development decisions away from taxa showing invasive potential.

Though wetlands cover a relatively small portion of the global land surface, many of the most harmful weeds are invaders of wetland habitats. This is true of wetlands in the Sacramento-San Joaquin Delta and Suisun Marsh. Invasive aquatic vegetation (IAV) is a particular concern for Delta managers of tidal wetland habitat, especially on restoration sites. As tidal wetland restoration continues across the landscape, new and existing sites experience invasion pressure once tidal reconnection occurs. There is no singular lead entity for managing invasive species in the Delta and Suisun Marsh, so interagency coordination is critical. To serve this need, the Delta Interagency Invasive Species Coordination (DIISC) Team was established in 2013 to provide a forum for agency collaboration on research and management needs related to invasive species. Through collaborative conversation, land managers and restoration practitioners identified a need for guidance on managing IAV.  In response to their request, DIISC Team members developed a quick start guide for management of IAV in tidal wetland sites, including species of concern, prioritization approaches, control methods, budgeting recommendations, funding opportunities, and links to comprehensive resources. The final guide will be available on the DIISC website, https://deltaconservancy.ca.gov/delta-inter-agency-invasive-species-team/.

Catalina Island is located off southern California and encompasses 47,884 acres, of which Catalina Island Conservancy (CIC) owns and manages 88%. In 2002, the Catalina Habitat Improvement and Restoration Program (CHIRP) began managing invasive plants across the island. In 2023, CIC partnered with California Institute of Environmental Studies (CIES) to seasonally treat invasive plants. The initial treatment season started with a series of challenges, leaving three novice contractors new to island ecology with minimal regional and institutional knowledge to navigate invasive plant management. Yet, the crew effectively treated 10 Natural Resource Conservation Service (NRCS) grant sites and 163.1 acres. In 2024, the same CIES crew returned and revisited NRCS grant areas, treating 145.2 acres. In 2025, two of the original CIES crew members returned in new roles to continue leading the project. The benefits of retaining staff were apparent, as the NRCS grant areas were treated as well as historical weed populations that had not been visited since before 2020. As of June, 125.4 acres were treated in 2025. CIC and CIES continue moving CHIRP forward, prioritizing flax-leaf broom (Genista linifolia). Methods include manual removal (pulling) and chemical application (cut/stump). Together CIC and CIES have learned valuable lessons, pivoted during unpredictable times, and expanded capabilities. They plan to continue working together and stewarding Catalina to protect its biodiversity. 

This project investigated how allelopathic compounds from the invasive artichoke thistle (Cynara cardunculus) affect native species in the endangered coastal sage scrub habitat (CSS) at Black Mountain, San Diego. With only 10–30% of the coastal sage scrub remaining and artichoke thistle present in at least 31 of California’s 58 counties, understanding the mechanisms by which the thistle inhibits native plant growth is crucial for developing effective mitigation measures. Therefore, this project focused on how leachates from fresh and decaying thistle roots, leaves, and soil affect the germination of key native species. Four experiments were conducted to assess germination success and germination time in response to leachate treatments. Using Generalized Linear Models (GLMs), ANOVA statistical tests, and estimated marginal means (emmeans) post-hoc comparisons, the data revealed several key findings. First, germination success (p = 0.0008) and germination time (p = 4.2e-5) were variable across species type, with some showing higher tolerance than others. Second, all leachates significantly reduced germination proportion (p = 1.02e-7) but had no effect on germination time (p = 0.71). Third, no significant difference was found between leachate types (leaf, root, soil), with all p-values exceeding 0.15. Finally, leachate source (living vs. decaying) affected germination success depending on the species (p = 0.017) but didn’t affect germination time (p = 0.48).

The Santa Clara River channel locally converted from a riparian woodland to an Arundo monoculture between 2012 – 2022. Early photos show a grove of tall trees by the channel edge that conceal an understory of Arundo, which is dominant in the distant central channel. A fire in December 2021 burned the entire grove and was hot enough to kill the trees, resulting in Arundo monoculture. Arundo was probably introduced into this grove of trees during past flooding events and added additional flammable biomass. The grove’s small size and proximity to a bridge, under which the flood channel was treeless and easy to colonize, may have made it particularly susceptible. A larger woodland grove a half mile upstream from the bridge also burned during a windstorm in January 2025. Burned Arundo clumps within the larger grove are abundant but relatively small and occupy less than 30% of the grove footprint. Most native trees are resprouting and Arundo stalks were not completely burned, presumably because the recent fire was not as hot as the fire in 2021. The management lesson is that if riparian woodlands are to survive in an Arundo-infested watershed, Arundo clumps within these groves should not be allowed to grow large and accumulate dead biomass. Site-specific management can help protect riparian woodlands independent of whether Arundo is controlled higher in the watershed.

Since 2014, the Santa Clara River Conservancy (SCRC) and UC Santa Barbara (UCSB) have led large-scale riparian restoration and ecological monitoring on the Santa Clara River (SCR) floodplain near Fillmore and Santa Paula, California. The SCR supports critical habitat for several listed avian species, including the endangered least Bell’s vireo, but has been heavily impacted by arundo (Arundo donax; giant reed). Arundo degrades habitat by overusing water, increasing wildfire risk, and displacing native riparian vegetation. To address these impacts, partners implemented mechanical and chemical removal of arundo, followed by passive and active revegetation aimed at restoring willow-cottonwood forest, riparian scrub, and emergent wetland habitat. Seasonal bird surveys, including intensive breeding season monitoring (March 15–September 15), have been conducted across restoration sites. In 2021, avian response data from Santa Paula (restored in 2014) showed positive trends in native habitat recovery and bird abundance. Project partners are now investigating whether similar trends are emerging in Fillmore, where restoration began in 2018. This presentation will share early results from Fillmore and begin to compare them with Santa Paula, helping inform future restoration strategies that support riparian habitat and bird conservation across the region.

Black Mountain Open Space Park in San Diego faces significant challenges in managing vegetation and mitigating wildfire risks due to its expansive, rugged terrain and fire-prone environment. Currently, manual inspection by rangers and volunteers is labor-intensive and time-consuming. This project proposes a drone-based system integrated with Artificial Intelligence (AI) and Geographic Information System (GIS) technology to streamline ecosystem maintenance and enhance wildfire risk detection. The drone system, equipped with high-resolution cameras, captures aerial imagery of the park, which is then analyzed by AI algorithms to identify dead plants, plants marked for watering, fire-prone zones, and invasive species such as Cynara cardunculus (cardoon), Brassica nigra (black mustard), Hirschfeldia incana (short-pod mustard), and Foeniculum vulgare (fennel). By automating image analysis, this system can scan large park areas at least five times more efficiently while also providing the ability to access hard-to-reach regions safely. The developed system also supports 2D and 3D terrain mapping, enabling rangers to visualize the park’s plants and wildfire risks from a virtual model. Furthermore, the system can be scaled to larger areas while still providing accurate, timely, and efficient solutions for vegetation health and wildfire risk management, including the removal of invasive species that increase the fire hazard.  

Volunteer programs led by natural resource staff at the Golden Gate National Recreation Area (GGNRA) have made progress in restoring biodiversity in the last thirty-five years on degraded public lands. From simple beginnings as a day of service in 1987, sprung weekly programs with passionate community volunteers. Over time, management complexity increased and drove development of new habitat restoration tools and control methods. Methods include mechanical (hand tools, power tools) and chemical (glyphosate) control, planting natives, browse protection, direct seeding, monitoring and most importantly, consistent community stewardship (follow-up). Plant communities have been restored at numerous park locations and include former Eucalyptus groves, (Eucalyptus globulus) French broom, (Genista monspessulana), Cape-ivy, (Delairea odorata), oblong spurge, (Euphorbia oblongata) and others dominated landscapes into riparian, wetlands, coastal swale, scrub, prairie and oak woodland habitats. And although we know that our work is never done, and significant challenges remain, biodiversity has been restored where work occurred, and sites require much less effort to maintain once biodiversity is increased and weed levels are dramatically reduced to maintenance level.

Community assembly frameworks propose that the species at a site are filtered by their traits from the regional species pool. Thatch producing non-native annual grasses, such as medusahead (Elymus caput-medusae), are common in the western United States. They alter environmental conditions and impose filters that have a mixed, but usually negative, effect on native plant, animal, and insect populations. In this study, we examine if traits commonly thought to lead to plant success in medusahead-dominated or thatch-dominated habitats correlate with plant emergence and growth in living medusahead, medusahead thatch, native vegetation, and bare ground cover types. We created plots of each cover type in a randomized incomplete block design. We selected 27 species native to and/or growing at the site that varied in seed mass, seed shape, native status, growth form, and bloom time. We planted seeds of each species into miniplots within each plot. We measured seed emergence, growth stage, and above-ground biomass. In this poster, we will present our results on seed traits. As hypothesized, in living medusahead cover and in thatch cover, greater seed mass, narrower seeds, and longer awns were positively correlated with number of plants. This study sheds light on how traits relate to community assembly; clarifies mechanisms underlying annual grass invasion and grassland restoration management outcomes; and informs future restoration efforts.

Agricultural drainage ditches often maintain year-round weedy vegetation which could become potential sources of invasive plant species and non-native insect pests for nearby agricultural areas and natural ecosystems. However, little research has explored vegetation composition in ditches in an agricultural, urban, and natural habitat matrix. In this study, we examined vegetation structure and composition in eight agricultural ditches in Ventura County between November 2023 and September 2024, as well as its relationship to the abundance of two non-native insect pests and a variety of beneficial arthropods. In each season, non-native species counts were higher than native species, peaking in March 2024 at 93.5%. The highest percentage of native species only reached 25.4% in September 2024. Moderately invasive non-native species such as Mustards (Brassica nigra and Hirschfeldia incana), Hemlock (Conium maculatum), and Bermuda (Cynodon dactylon) were among the most common species. Additionally, invasive Watercress (Nasturtium officinale) proliferated in most of the ditches with water, suggesting that these ditches can be sources of both invasive aquatic and terrestrial species. Furthermore, key insect pests and their natural enemies were quantified in association with these plant species. These results can inform new guidelines to prevent ditches from acting as reservoirs for non-native plants and facilitating their spread to nearby grassland, riparian, and wetland habitats.

Urban expansion and ornamental gardening are major drivers of non-native plant spread, disrupting native plant–pollinator interactions in southern California. Tropical milkweed (Asclepias curassavica), a non-native species favored for its evergreen habit and ornamental appeal, is hypothesized to interfere with monarch butterfly migratory cues, delay reproductive diapause, and increase susceptibility to the protozoan parasite (Ophryocystis elektroscirrha), which causes deformities, reduced survival, and mortality in monarchs. In contrast, native milkweed species undergo seasonal senescence that better aligns with monarch life cycles and migratory behavior. In 2022, UC Santa Barbara established two milkweed common gardens—one in Santa Barbara (cooler/wetter) and one in Fillmore (warmer/drier)—to evaluate plant phenology, source variation, and monarch caterpillar abundance across varying climate conditions for native narrowleaf milkweed (Asclepias fascicularis). Preliminary results indicate that all A. fascicularis populations entered winter dormancy when monarchs are typically present at overwintering sites. This poster will present planting recommendations based on phenological data to support monarch conservation programs, enhance habitat connectivity, reduce ecological risks associated with non-native milkweed, and promote the long-term resilience of monarch butterfly populations.

Climate change is altering precipitation, with changes to both mean and variability that will impact biodiversity patterns and make it critical to understand how species and communities will respond under less predictable precipitation regimes. One way species contend with unpredictable environments is via seed banking. Seed-banking species delay germination until conditions are favorable. To understand how altered precipitation influences the seed bank and community dynamics, we investigated seed banking in a Southern California dryland ecosystem with distinct winter and summer annual plant communities. We asked: 1. How does soil seed bank composition vary between seasons, within seasons, and across treatments from the aboveground community? and 2. How do non-native species contribute to seed bank dynamics and community structure under different seasonal and treatment conditions? We characterized the seed bank by collecting soils adjacent to 12 established plots that include control and water addition treatment replicates. Aboveground composition data was collected at these plots from 2018-2023. Over a 2 years, species were germinated in a greenhouse and identified. We found that seed bank and aboveground composition significantly differed in both summer and winter, and those differences were driven by non-native species. Our results suggest a potential role of non-native species in shaping how communities respond to altered precipitation across seasonal desert communities.

Parafreutreta regalis, a gall-forming fly, is currently the only approved biological control agent for Cape Ivy (Delairea odorata). Parafreutreta regalis was approved for open release in 2016, and has now established at seven field sites across California’s coastal counties. Consistent surveys have tracked the agent’s establishment and impacts, but the dispersal ability of P. regalis has remained unclear. Documenting dispersal patterns is critical for evaluating the large-scale implications of the biocontrol program and for informing future release strategies, so this project is intended to characterize the spread of P. regalis from known release points. In November of 2024, gall surveys were conducted at two release sites in Santa Barbara County. Starting at release points, Cape Ivy was inspected for galls. Surveyors collected GPS coordinates of galls found at increasing distances from initial release points. Survey data were mapped using QGIS to estimate dispersal distances. Initial surveys indicate a minimum dispersal of 5km, and extending into multiple tributary creeks. These surveys were continued through summer 2025, incorporating more release sites and documenting annual population expansion. Further surveys will help to create a more comprehensive understanding of the biocontrol program for Cape Ivy.

An important factor in successful restoration of invaded ecosystems is the establishment of native plants with traits that reduce further invasion. Faster growth, for example, can give native species a competitive edge over invasive species during establishment through more efficient resource acquisition. Plant traits often vary among populations from different regions, possibly due to maternal effects or genetic differentiation across climate gradients, but it is unknown whether native plants from areas differing in temperature and precipitation improve restoration outcomes. For example, faster growing plants may outcompete invasive species. We investigated how seed source (provenance) affects growth and establishment of three native California shrub species from three different climates. We measured traits related to competition with invasives: resource acquisition, drought tolerance, and floral resources from 66 individuals of Black Sage (Salvia mellifera), California Buckwheat (Eriogonum fasciculatum), and Deer Weed (Acmispon glaber) (11 per species per provenance). Early results show trait differences among species, with several showing plants from cooler and drier areas had faster initial growth compared to those sourced locally. These early findings suggest that to improve restoration success by making native populations more competitive with invasive species a focus on identifying species with competitive traits may be more effective than focusing on seed provenances.

Hybridization between native species and introduced (non-native) species of the same genus can lead to genetic swamping, or the loss of native genes. In California rivers, Western sycamores (Platanus racemosa) are native, drought-tolerant foundational trees that provide important wildlife habitat and ecosystem services. However, it is likely that hybridization between Western sycamores and introduced, ornamental London plane trees (P. hispanica) has led to the widespread occurrence of hybrids that may not provide the same ecological benefits as pure natives. Many younger trees in riparian areas of Santa Barbara and Ventura counties, including those planted in restoration projects, have morphological characteristics of both trees, prompting our investigation into their genetic status. Our goals are to document the presence of hybrids in coastal rivers and at restoration sites, model the temporal progression of hybridization and identify pure lines of native Western sycamores that can be used as propagule sources for future restoration projects. We collected over 200 samples from rivers, restoration sites, and plant nurseries throughout the region. Population structure is being assessed using nextRAD genotyping and tree age determined using tree rings, which may reveal temporal trends in hybridization and help identify native trees for propagule collection. Preliminary results suggest that many naturally occurring and restoration stock sycamores are not of pure native lineage.

We share lessons learned since the 2008 establishment of a community-based program to restore coastal sage scrub habitat in an urban parklands setting in Los Angeles. We describe the logistics involved and outcomes achieved in long-term investment in a site surrounded by highly diverse communities. Our approach has helped us to evolve and expand our strategies for both community outreach and habitat restoration over time. Our project’s People Goals include: (1) providing the community with knowledge about and opportunities to steward their local ecology, increasing direct engagement in issues like habitat loss, water conservation, and wildfire prevention; (2) collaborating with restoration ecologists, field biologists, and state and local agencies and organizations to capitalize on existing expertise and maximize funding opportunities; (3) work force development for students and early-career professionals to gain access to fieldwork experience, certificate programs, and paid work. Our project’s Habitat Goals include: (1) removal by hand of invasive plants (Brassica nigra, Hirschfeldia incana, Raphanus sativus, Glebionis coronaria); (2) restoration of coastal sage scrub habitat through plant installation and direct seeding; (3) plant propagation and seed collection on site where restoration is being conducted; (4) development of a monitoring program that can train volunteers to conduct vegetation and wildlife surveys at restoration sites.

Riparian restoration, including invasive species removal, in complex agricultural landscapes has shown to enhance ecosystem services, such as pest control and pollination. Yet, we lack an understanding of how specific vegetation characteristics drive these benefits. Vegetation structure modifies local temperature conditions through solar radiation reflection and microclimate creation, which is important for temperature-sensitive arthropod communities that provide essential ecosystem services. However, the combined effects of thermal properties and vegetation structure on biodiversity remains understudied. Here, we employ ground-based measurements and remote sensing, including aerial LiDAR and thermal infrared imaging (UAV, Landsat 9), to measure vegetation structure and thermal characteristics in orchards and natural areas along restored and unmanaged riparian corridors in the Santa Clara River Valley (SCRV). The SCRV is a matrix of agricultural lands and riparian and upland habitats. Restoration in the SCRV has primarily focused on removal of Arundo donax from the riparian corridor. Our aims are to 1) assess how 3D vegetation and thermal metrics differ as a function of management types (lemon/avocado orchards, riparian area) and distance from natural riparian habitat; 2) determine whether 3D vegetation structural metrics are related to thermal properties; and 3) examine relationships between vegetation composition, including cover of Arundo donax and other invasive species, and thermal metrics and measures of arthropod biodiversity, including abundance of pests and beneficial arthropods. Our goal is to provide evidence-based recommendations for land managers on optimizing vegetation structure and temperature regulation to restore structurally diverse habitats that enhance ecosystem services and support biodiversity and sustainable agricultural practices.

With the challenge of managing over 30,000 acres of protected wildlands, the Irvine Ranch Conservancy (IRC) works to connect our local community with the land while protecting and restoring natural resources. Several program areas are utilized within our nonprofit to facilitate the goal of protecting, restoring, and enhancing Southern California’s urban wildlands. Volunteers serve a vital role in supporting our mission as well as providing a direct conduit into the greater community. Currently, public facing invasive species-related activities, with the dual goal of managing invasive populations and raising public awareness, are led by IRC staff. Out of the necessity to increase engagement with the public, Invasive Species Control Volunteer Training was developed and implemented this year for a group of 15 IRC volunteers. This Invasive Species Control training provides plant identification skills, best management practices, and future volunteer pathways. Through completing this training, volunteers received improved skills, increased confidence, and a certification enabling them to lead their own invasive control activities.

In Southern California, the prevalence of major insect pest species discourages citrus and avocado growers from reducing pesticide applications, despite significant health risks and diminishing returns. Integrated pest management (IPM) offers an alternative by boosting natural biocontrol, often through native or non-native hedgerows that attract beneficial arthropods like pest enemies. Since many different plant species are used in Southern California hedgerows, developing specific management and planting criteria is challenging. However, plant traits and their influence on beneficial arthropods could be used to guide implementation. Therefore, the objective of this project is to identify plant traits that promote beneficial plant-arthropod relationships and provide insights for future IPM strategies. Here, we present data on plant traits and arthropod communities from hedgerows planted at two citrus and four avocado orchards in Ventura County, CA. Each hedgerow consists of seven native California species and has been sampled for phenological, morphological, and physiological plant traits. Arthropod community metrics were collected simultaneously using a combination of visual and vacuum surveys. Our results will include traits related to plant size, leaf characteristics, and floral output, and how these correlate with pest and natural enemy abundance. Overall, this work advances the science and application of native hedgerows to optimize their performance in agriculture.

The San Diego Management and Monitoring Program has developed a collaborative program, called SPARCS (Suppression and Planning Actions for Restoring Communities and Species), with local fire and land managers to protect natural resources—including native habitats threatened by invasive plant species—during wildfire response. Invasive plants are a key concern in post-fire landscapes, where disturbed areas are vulnerable to rapid colonization. This program proactively supports fire management efforts by connecting fire personnel with local ecological expertise to minimize the spread and establishment of invasive species, among many other impacts. Partnering with agencies such as BLM, CalFire, USFWS, NPS, San Diego County, and NGOs, the program focuses on two key components: (1) Creation of two integrated databases and interactive maps—one detailing fire-relevant infrastructure, and the other identifying sensitive ecological and cultural areas, including habitats vulnerable to invasive plant expansion; and (2) Formation of a local cohort of Wildland Fire Resource Advisors (READs) trained to use these tools during fire suppression and repair activities. By promoting ecologically informed decisions, we aim to reduce the impacts from suppression activities, including spread of invasive species post-fire, and support land managers in pre-fire planning and long-term recovery.

The high severity nature of pile burning has the potential to directly address negative soil legacies of invasive annual plant species. By strategically burning piles in highly invaded grasslands, soil seed banks, microbial communities, and nutrients may be altered in favor of native plant re–establishment. On Wappo homelands at Pepperwood Preserve (Santa Rosa, CA), stewards work with fire to achieve various goals, including pile burning for the reduction of fuel loads. In fall 2024, soil was harvested for the quantification of soil legacies within burn scars of pile burns and just outside of them, in the surrounding unburned plant communities. To understand the contributions of non-native annual plants to the soil seed banks and fire’s impacts to them, a seed bank study was conducted in a lath house at UC Davis. Field soil was layered over a potting soil mix in 10”x10” and 2.5” deep seed trays. Soils were watered as needed, typically every second to third day, until seedlings were identifiable. For each tray, data on species diversity and abundance was collected. Although data have not formally been analyzed, anecdotal observations suggest significant differences between the seeds present in burn scar soils and in unburned soils on invaded plant communities. As an already widespread ecological stewardship technique, this research can illuminate the importance of strategic placement of pile burns on invaded soils and the impacts of fire to native species in the seed bank.

 

Hypericum canariense, a woody, rhizomatous invasive plant spreading along California’s north coast, poses major challenges for early detection, monitoring, and response. We launched a collaborative initiative to build a drone-based image library using machine learning to improve detection in remote, rugged terrain. This marks Phase 1 of a broader IPM strategy to accelerate response and reduce treatment costs. The project integrates UAV image capture, ortho-processing, and species annotation to generate a replicable training library for mapping and modeling. The library informs restoration on a 500-acre site—known as the Mushroom Farm—six miles south of Pescadero in San Mateo County, and supports a shovel-ready treatment campaign with environmental permitting and matching funds in place. Though the initial scope focuses on a single species and site, library protocols are built for regional scalability and are already being adapted to Arundo donax. We’ll highlight real-world applications in treatment prioritization, habitat triage, and cost-benefit analysis, as well as next steps to validate detection accuracy, test under varied canopy conditions, and develop open-access drone-based IPM protocols for land managers. By bridging detection and implementation, this project delivers a scalable, transferable model to enhance early detection and rapid response for invasive plant management in California’s dynamic landscapes.

In 2021, East Bay Regional Park District (EBRPD) began developing an Early Detection Rapid Response (EDRR) program. The goal of the EBRPD EDRR program is to find new populations of highly invasive plants early, and to map and remove them before they spread. First, we divided the EBRPD 73-Park system lands into six geographic regions: Shoreline, Delta, East Contra Costa Grasslands, North Hill Parks, South Hill Parks, and Southeast Parks. We also included an “Aquatic” Unit which is for floating or submerged aquatic weeds found in lakes and large waterbodies. Then, using Calflora.org, we developed EDRR species lists for each region based on which invasive plants are documented in or near the region, and we consulted with partner organizations in the area to add newly detected species. In 2025, we developed on-line EDRR trainings for each region, including basic plant identification and skits with park rangers demonstrating EDRR mapping and work-flow. The training included how to map EDRR weeds using a custom Survey123 application which syncs observations to the EBRPD GIS database. Additionally, in 2025, we held three in-person trainings for 34 EBRPD staff. Some of the newly detected EDRR species in EBRPD are greater celandine (Chelidonium majus) and longflowered veldtgrass (Ehrharta longiflora). Future plans include development of an IPM dashboard for each park which will incorporate EDRR mapping and streamline invasive plant management.

French broom (Genista monspessulana) is a shrub native to the Mediterranean Region that has invaded over 100,000 acres in the coastal hills and Sierra foothills of California, increasing risk of wildfire and decreasing biodiversity. In its native region, the plant does not occur in high densities, presumably because it is controlled by natural enemies. The psyllid, Arytinnis hakani, is an insect that sucks the sap of French broom, and it has only been found on this plant. In Australia, where French broom also is invasive, the psyllid dramatically reduced the plant’s population. In order to obtain a permit to release the psyllid in the USA, it is necessary to show that it would not impact any nontarget species. Experiments have shown that the psyllid can develop on some species of lupines when they are confined in cages, or when the plants are close to heavily infested broom plants. However, lupine plants that are at least 5 m (15 ft) away were not attacked. We are requesting a permit to introduce this insect as a biological control agent. This would be the first agent available for French broom, which could provide sustainable reduction of this persistent invader.

Feral European olives (Olea europaea) have spread from the protected Smuggler’s Cove Historical Olive Grove on limuw, also known as Santa Cruz Island (SCI), which is one of the five islands managed by Channel Islands National Park (CHIS) off the coast of Southern California. The cultural protection of the olive grove prevents the full eradication of feral olives on the island, and requires continued management to prevent further spread. Feral olives were listed as a target invasive species by CHIS in 2007, and California Institute of Environmental Studies (CIES) began working olive management in 2023. Olives are notoriously difficult to remove and management practices on SCI have not been consistent. Our goal in 2025 is to investigate the efficacy of different olive management/treatment practices. Current practices include manual removal with Pulaskis, girdling, drill and fill, and cut stump. Chemicals used include glyphosate 2% (Roundup), triclopyr 2% (Garlon 4 Ultra), and imazapyr 1% (Polaris). We use ArcGIS Field Maps to record weed and treatment locations. We present best practices for managing invasive olive trees, streamlined approaches of successful management, and data on successful kill rates.