Introduced exotic plants can drive ecosystem change. We studied invasion and establishment of Brassica tournefortii (African mustard), a noxious weed, in the Chemehuevi Valley, western Sonoran Desert, California. We used long-term data sets of photographs, transects for biomass of annual plants, and densities of African mustard collected at irregular intervals between 1979 and 2009. We suggest that African mustard may have been present in low numbers along the main route of travel, a highway, in the late 1970s; invaded the valley along a major axial valley ephemeral stream channel and the highway; and by 2009, colonized 22 km into the eastern part of the valley. We developed predictive models for invasibility and establishment of African mustard. Both during the initial invasion and after establishment, significant predictor variables of African mustard densities were surficial geology, proximity to the highway and axial valley ephemeral stream channel, and number of small ephemeral stream channels. The axial valley ephemeral stream channel was the most vulnerable of the variables to invasions. Overall, African mustard rapidly colonized and quickly became established in naturally disturbed areas, such as stream channels, where geological surfaces were young and soils were weakly developed. Older geological surfaces (e.g., desert pavements with soils 140,000 to 300,000 years old) were less vulnerable. Microhabitats also influenced densities of African mustard, with densities higher under shrubs than in the interspaces. As African mustard became established, the proportional biomass of native winter annual plants declined. Early control is important because African mustard can colonize and become well established across a valley in 20 yr.

Many introduced species are capable of both sexual and vegetative reproduction. Our understanding of the ecology of such species depends on the trade-offs between vegetative and sexual reproduction and the ecological conditions that favor both modes of reproduction and how those factors influence the population ecology of introduced species. Here, we studied the efficacy of propagation via both seeds and rhizomes in Johnsongrass, a widespread invasive grass whose success is due to its prolific production of shattering seeds and rhizomes, the latter of which are readily dispersed by anthropogenic and natural processes. In a common garden in Virginia, we varied the density of seeds and rhizomes and manipulated whether recruits experienced interspecific competition. Johnsongrass recruited from both seeds and rhizomes. We compared the efficacy of seeds and rhizomes on a per propagule basis and by standardizing them according to their total carbon content. Rhizomes were more efficient than seeds on a per propagule basis, but seeds propagated more efficiently than rhizomes on a per unit of carbon basis, establishing in nearly all plots and obtaining much greater biomass than rhizomes. We also found that rhizomes were subject to stronger negative density dependence than seeds and were more sensitive to site variation and competition. Our results suggest that, provided sufficient dispersal, a single Johnsongrass plant produces enough propagules to establish over more than a hectare, even at relatively low propagule densities. Proper understanding of both seed and vegetative propagation is crucial for understanding the ecology of this and other invasive species that utilize multiple reproductive modes.

Invasive populations of Dalmation toadflax [Linaria dalmatica (L.) Mill.] and yellow toadflax (Linaria vulgaris Mill.) are widespread throughout the Intermountain West, where gene flow between these nonnative species is producing vigorous and fertile hybrids. These hybrid toadflax populations are less responsive to herbicides than either parent species, and biocontrol agents routinely released on L. dalmatica and L. vulgaris often fail to establish on hybrid hosts. Early detection of hybrid Linaria populations is therefore essential for effective management, but resources are limited for scouting large expanses of range and wildland. We used species distribution modeling to identify environmentally suitable areas for these invasive Linaria taxa in Montana, Wyoming, and Colorado. Areas suitable for hybrid Linaria establishment were estimated using two different modeling approaches: first, based on known hybrid occurrence and associated environmental conditions, and second, based on zones environmentally suitable for co-occurrence of the parent species. This also allowed comparison of different model outputs, especially relevant when modeling emerging invasives, such as novel hybrids, with minimal occurrence data. Combining the two model outputs identified areas at greatest risk of hybrid Linaria invasion, including parts of north-central Montana, where model estimates indicate the hybrid may spread without prior co-invasion of the parents. Potential hybrid hot spots were also identified in western Montana; northwestern, northeastern, and southeastern Wyoming; and the Western Slope and Front Range of Colorado. Despite relatively few confirmed occurrences of hybrid populations to date, our results indicate that extensive spread of hybrid populations is possible within the studied area. Model-based maps of potential Linaria distributions will allow area weed managers to direct limited resources more effectively for locating and controlling these invaders.

Ecological impacts from invasive plants that have been identified include reductions in biodiversity, changes in resource cycling, and disruptions of ecosystem function. To mitigate these negative ecological impacts, managers work to remove invasive plants. However, removal does not necessarily immediately lead to a return to the uninvaded ecological state. Similarly, the accumulation rate of ecological impacts following invader establishment is almost entirely unknown for most species, hindering identification of optimal management times. The accumulation and loss (so-called legacy effects) of impacts following invader establishment and removal represent an “invasion shadow.” To begin to understand invasion shadows, we measured the changes in biotic and abiotic ecological impacts during establishment and following removal of the forest understory invader Japanese stiltgrass. We found that when the abiotic metrics were considered, seeded areas became more functionally similar to the invaded landscape and removed areas became more similar to the uninvaded landscape. However, while the plant community did not change in a 3-yr period during a new invasion, following invader removal, it became less similar to both the invaded and uninvaded landscape altogether, suggesting legacies. Surprisingly, all changes occurred almost immediately and persisted following invader establishment and removal. Our results show, at least in a 3-yr period, that ecosystems can respond to changes in invader abundance, and in some cases simply removing the invader could result in long-term changes to the resident plant community.

In 2016 and 2017, 98 separate commercially available bird feed mixes were examined for the presence of weed seed. All weed seed contaminants were counted and identified by species. Amaranthus species were present in 94 of the 98 bags of bird feed. Amaranthus species present in bird feed mixes included waterhemp [Amaranthus tuberculatus (Moq.) Sauer], redroot pigweed (Amaranthus retroflexus L.), Palmer amaranth (Amaranthus palmeri S. Watson), smooth pigweed (Amaranthus hybridus L.), and tumble pigweed (Amaranthus albus L.). Amaranthus palmeri was present in 27 of the 98 mixes. Seed of common ragweed (Ambrosia artemisiifolia L.), kochia [Bassia scoparia (L.) A.J. Scott], grain sorghum [Sorghum bicolor (L.) Moench], wild buckwheat (Fallopia convolvulus L., syn: Polygonum convolvulus), common lambsquarters (Chenopodium album L.), large crabgrass [Digitaria sanguinalis (L.) Scop.], and Setaria species were also present in bird feed mixes. A greenhouse assay to determine Amaranthus species seed germinability and resistance to glyphosate revealed that approximately 19% of Amaranthus seed in bird feed mixes are readily germinable, and five mixes contained A. tuberculatus and A. palmeri seed that were resistant to glyphosate. Results from linear regression and t-test analysis indicate that when proso millet (Panicum miliaceum L.), grain sorghum, and corn (Zea mays L.) were present in feed mixes, Amaranthus seed contamination was increased. The presence of proso millet and grain sorghum also increased contamination of grass weed species, while sunflower (Helianthus annuus L.) increased A. artemisiifolia contamination and safflower (Carthamus tinctorius L.) increased contamination of Bassia scoparia.

Population genetic studies of within- and among-population genetic variability are still lacking for managed submerged aquatic plant species, and such studies could provide important information for managers. For example, the extent of within-population genetic variation may influence the potential for managed populations to locally adapt to environmental conditions and control tactics. Similarly, among-population variation may influence whether specific control tactics work equally effectively in different locations. In the case of invasive Eurasian watermilfoil (Myriophyllum spicatum L.), including interspecific hybrids with native northern watermilfoil (Myriophyllum sibiricum Kom.), managers recognize that there is genetic variation for growth and herbicide response. However, it is unclear how much overall genetic variation there is, and how it is structured within and among populations. Here, we studied patterns of within- and among-lake genetic variation in 41 lakes in Michigan and 62 lakes in Minnesota using microsatellite markers. We found that within-lake genetic diversity was generally low, and among-lake genetic diversity was relatively high. However, some lakes were genetically diverse, and some genotypes were shared across multiple lakes. For genetically diverse lakes, managers should explicitly recognize the potential for genotypes to differ in control response and should account for this in monitoring and efficacy evaluation and using pretreatment herbicide screens to predict efficacy. Similarly, managers should consider differences in genetic composition among lakes as a source of variation in the growth and herbicide response of lakes with similar control tactics. Finally, laboratory or field information on control efficacy from one lake may be applied to other lakes where genotypes are shared among lakes.

Invasions can be genetically diverse, and that diversity may have implications for invasion management in terms of resistance or tolerance to control methods. We analyzed the population genetics of Russian-olive (Elaeagnus angustifolia L.), an ecologically important and common invasive tree found in many western U.S. riparian areas. We found three cpDNA haplotypes and, using 11 microsatellite loci, identified three genetic clusters in the 460 plants from 46 populations in the western United States. We found high levels of polymorphism in the microsatellites (5 to 15 alleles per locus; 106 alleles total). Our native-range sampling was limited, and we did not find a genetic match for the most common cpDNA invasive haplotype or a strong confirmation of origin for the most common microsatellite genetic cluster. We did not find geographic population structure (isolation by distance) across the U.S. invasion, but we did identify invasive populations that had the most diversity, and we suggest these as choices for initial biological control–release monitoring. Accessions from each genetic cluster, which coarsely represent the range of genetic diversity found in the invasion, are now included in potential classical biological control agent efficacy testing.

Wild potato contains about 100 species that are native to the Americas from the southwestern United States to central Chile and adjacent Argentina, Uruguay, Paraguay, and southern Brazil. We report the occurrence of naturalized populations of the wild potato Solanum chacoense in seven sites in southern Australia, eastern China, England, New Zealand, the eastern United States, central Peru, and east-central Argentina. Modeling similar climatic niches on the basis of the distribution of S. chacoense from South America shows that observations of naturalized S. chacoense overlap with predicted areas. A literature review reveals that although S. chacoense possesses traits typical of an invasive species, all populations presently appear to be contained near their site of introduction.

Producers facing infestations of invasive annual grasses regularly voice the need for practical revegetation strategies that can be applied across broad landscapes. Our objective was to determine the potential for scaling up the single-entry approach for revegetating medusahead-infested rangeland to broader, more heterogeneous landscape-scale revegetation of winter annual grass–infested rangeland. We hypothesized, when applied on a highly variable landscape scale, the combination of imazapic and seeding would provide highest abundance of perennial grasses and lowest amount of annual grasses. Treatments included a control, seeding of crested wheatgrass (‘Hycrest’) and Sandberg's bluegrass, spraying (60 g ai ha−1 imazapic), and a simultaneously applied combination of spraying and seeding. The HyCrest and Sandberg's bluegrass seeding rates were 19 and 3.4 kg ha−1, respectively. The treatments were applied to large plots (1.4 to 8 ha) and replicated five times, with each replication located in different watersheds throughout southeastern Oregon. This study shows that the single-entry approach can be scaled up to larger landscapes, but variation within establishment areas will likely be high. This procedure should reduce the costs over multientry treatment applications and make revegetating annual grass–infested rangeland across landscapes more affordable.

Biological invasions are one of the grand challenges facing society, as exotic species introductions continue to rise and can result in dramatic changes to native ecosystems and economies. The scale of the “biological invasions crisis” spans from hyperlocal to international, involving a myriad of actors focused on mitigating and preventing biological invasions. However, the level of engagement among stakeholders and opportunities to collaboratively solve invasives issues in transdisciplinary ways is poorly understood. The Biological Invasions: Confronting a Crisis workshop engaged a broad group of actors working on various aspects of biological invasions in Virginia, USA—researchers, Extension personnel, educators, local, state, and federal agencies, nongovernmental organizations, and land managers—to discuss their respective roles and how they interact with other groups. Through a series of activities, it became clear that despite shared goals, most groups are not engaging with one another, and that enhanced communication and collaboration among groups is key to designing effective solutions. There is strong support for a multistakeholder coalition to affect change in policy, public education/engagement, and solution design. Confronting the biological invasions crisis will increasingly require engagement among stakeholders.

Neotropical bracken fern invades disturbed forests and burned and abandoned pastures in Latin America, inhibiting the growth of associated vegetation and altering community structure. Cutting of all aboveground vegetation every 6 to 12 mo has proven to be inefficient as a control method. We studied the impact of selective cutting of bracken every 2 mo, shading, and a combination of cutting + shading during 14 mo in a bracken-dominated, abandoned pasture in Veracruz, Mexico. At the end of the experiment, cutting with or without shading drastically reduced bracken cover from >90% to less than 1%, decreased leaf number from 18 to fewer than two leaves per m2, and depleted bracken leaf biomass. The significant reduction of bracken was correlated with a significant 3.9- to 5.7-fold increase in richness of other plant species. Cutting without shading was the only treatment that significantly reduced rhizome biomass to less than 62% of control plots, whereas cutting + shading was the only treatment to promote a significant increase in both cover and shoot biomass of successional plant species. Selective cutting of P. arachnoideum repeated every 2 mo was more successful than nonselective cuttings repeated at longer intervals, because it removed newly emerging leaves before their complete expansion and supported the recovery and reestablishment of other plant species, which may help to control bracken. Although costs for the first year of selective cutting were twice as much as for nonselective cutting, it may prove less expensive and more efficient than nonselective cutting in the long term.

Broom snakeweed is one of the most widespread range weeds in western North America. Although a native plant, it increases with disturbance such as overgrazing, fire, and drought, and can dominate sites. The objective of this study was to test the hypothesis that defoliation of broom snakeweed alone, and along with associated grasses, would reduce its vigor and increase its mortality in bunchgrass plant communities. The study was conducted at two locations: near Nephi, UT in an invaded crested wheatgrass stand and at Howell, UT in a bluebunch wheatgrass/Wyoming big sagebrush community. Clipping treatments consisted of (1) untreated Control; (2) All Clip—clipping all herbaceous vegetation 2 cm above the soil surface, and current season foliar growth of snakeweed; (3) Grass Clip—clipping all grass and forb plants; (4) Snakeweed Clip—clipping current season foliar growth. Treatments were randomly assigned to 1-m2 plots and clipped in May or late August. Plots were measured and clipped at the respective seasons annually from 2004 to 2007. Defoliation of snakeweed in spring in the Snakeweed Clip treatment caused higher mortality and lower size and vigor of remaining plants than the other treatments at the end of the study. Clipping all vegetation also reduced snakeweed density at Nephi, but not at Howell. There was little regrowth of bluebunch wheatgrass at Howell in the All Clip treatment; thus, it was likely to have not competed with snakeweed regrowth for limited soil moisture. Bluebunch wheatgrass cover declined at Howell in the All and Grass Clip treatments. Crested wheatgrass was not adversely affected by spring defoliation in the All and Grass Clip treatments, and it increased in the Snakeweed Clip treatment. There were few differences in the fall defoliations. Spring defoliation of snakeweed put it at a competitive disadvantage with both intact perennial bunchgrasses and regrowth crested wheatgrass, thus enhancing its mortality.

Nine sites of cogongrass were included in a study of genotypic diversity and spread dynamics at the point of introduction and its adjacent areas in the southern United States. Clones evaluated with two primer pairs yielded a total of 137 amplified fragment length polymorphism (AFLP) loci of which 102 (74.4%) were polymorphic. Genetic diversity was measured as the percentage of polymorphic, Shannon's information index, Nei's gene diversity, and panmictic heterozygosity. Nei's gene diversity (HS) across all nine sites was estimated to be 0.11 and within site gene diversity ranged from 0.06 to 0.16. Bayesian estimate of gene diversity and Shannon's information index were higher (0.17 and 0.17, respectively). The samples from the point of introduction (Pi) had the lowest genetic diversity for all types of estimates. Within site variance accounted for 56% of the total variation and among site variance 44% (P < 0.05). Differentiation among sites was assessed using F ST. The greatest difference was found between the Pi and the others. No relationship was found between genetic and geographic distances. Principal component analysis as well as cluster analysis separated individuals into three main clusters. The Pi formed a separate subcluster. Gene flow (Nm), inferred from Φ-statistics describing the genetic differentiation between pairs of sites ranged from 0.6 to 5.55. The lack of significant relationship between gene flow and geographic distance as well as genetic and geographic distances suggests that the invasion dynamics of cogongrass into the southern United States is primarily through anthropogenic activities and to the lesser extent through natural forces.

Many large-scale management programs directed toward the control of waterhyacinth rely on maintenance management with herbicides. Improving the implementation of these programs could be achieved through accurately detecting herbicide injury in order to evaluate efficacy. Mesocosm studies were conducted in the fall and summer of 2006 and 2007 at the R. R. Foil Plant Science Research Center, Mississippi State University, to detect and predict herbicide injury on waterhyacinth treated with four different rates of imazapyr and glyphosate. Herbicide rates corresponded to maximum recommended rates of 0.6 and 3.4 kg ae ha−1 (0.5 and 3 lb ac−1) for imazapyr and glyphosate, respectively, and three rates lower than recommended maximum. Injury was visually estimated using a phytotoxicity rating scale, and reflectance measurements were collected using a handheld hyperspectral sensor. Reflectance measurements were then transformed into a Landsat 5 Thematic Mapper (TM) simulated data set to obtain pixel values for each spectral band. Statistical analyses were performed to determine if a correlation existed between bands 1, 2, 3, 4, 5, and 7 and phytotoxicity ratings. Simulated data from Landsat 5 TM indicated that band 4 was the most useful band to detect and predict herbicide injury of waterhyacinth by glyphosate and imazapyr. The relationship was negative because pixel values of band 4 decreased when herbicide injury increased. At 2 wk after treatment, the relationship between band 4 and phytotoxicity was best (r 2 of 0.75 and 0.90 for glyphosate and imazapyr, respectively), which served to predict herbicide injury in the following weeks.

Sulfur cinquefoil is an exotic, perennial forb that invades a wide range of ecosystems in western North America. It forms dense populations and often threatens native plant species and communities. In this study, we address the following questions: (1) what herbicides, rates, and application times are most effective at reducing sulfur cinquefoil abundance while having the least impact on native plants; and (2) does postherbicide seeding with native grass species increase native plant abundance? In 2002, we experimentally examined the effects of five herbicides (dicamba + 2,4-D; metsulfuron-methyl; triclopyr; glyphosate; and picloram) at two rates of application (low and high), three application times (early summer, fall, and a combined early summer–fall treatment), and two postherbicide seed addition treatments (seeded or not seeded) on sulfur cinquefoil abundance, plant community composition, and species richness. Experimental plots were monitored through 2005. Picloram was the most effective herbicide at reducing sulfur cinquefoil density, the proportion of remaining adult plants, and seed production. The effects of picloram continued to be evident after 3 yr, with 80% reduction of sulfur cinquefoil in 2005. In addition, seeding of native grass seeds alone (no herbicide application) reduced the proportion of sulfur cinquefoil plants that were reproductively active. Despite reductions in sulfur cinquefoil abundance, all treatments remained dominated by exotic species because treated areas transitioned from exotic forb- to exotic grass-dominated communities. However, a one-time herbicide application controlled sulfur cinquefoil for at least 3 yr, and therefore might provide a foundation to begin ecological restoration. Herbicide applications alone likely are to be insufficient for long-term sulfur cinquefoil control without further modification of sites through native grass or forb seeding. Integrating herbicides with native plant seeding to promote the development of plant communities that are resistant to sulfur cinquefoil invasion is a promising management approach to ecological restoration.

Japanese barberry is listed as an invasive shrub in 20 states and four Canadian provinces. Control of Japanese barberry was evaluated using several two-step processes over 16 mo using a total of 1,100 clumps at six study areas. Initial treatments in spring (prescribed burning, mechanical mowing with a brush saw or rotary wood shredder) reduced the size of established barberry clumps. Follow-up treatments in midsummer to kill new ramets that developed from surviving root crowns were foliar applications of triclopyr or glyphosate, directed heating with a propane torch, and untreated controls. Mortality was defined as the absence of ramets from a root crown and not the mortality of individual ramets of a given clump. Clump mortality and size of new ramets did not differ among initial treatments. However, larger clumps had higher survival and larger sprouts than smaller clumps 16 mo after initial treatment. Effectiveness of follow-up treatments varied by clump size. Two follow-up treatments of directed heating using propane torches were as effective as herbicides for clumps that were initially smaller than 120 cm. For clumps with pretreatment sizes of 120 cm and larger, clump mortality following herbicide treatments (90%) and directed heating (65%) was greater than for clumps that had no follow-up treatments (35%). Although clump sizes did not differ between follow-up methods 1 yr after treatment, both follow-up treatments resulted in smaller clumps than untreated controls. Effective control of Japanese barberry can be achieved in a single growing season by integrating an early-season initial treatment (prescribed fire or mechanical) that kills the aboveground tissues with a midseason follow-up treatment such as directed heating or targeted herbicide application.

Nonnative invasive species are one of the biggest threats to biodiversity worldwide. In many cases the extent of the area invaded by an invasive species is so substantial that there are simply insufficient resources to control and manage the full extent of the invasion. Efficient use of resources and best management practices are critical for achieving invasive species management goals. Systematic regional planning is one way to quantitatively prioritize different management actions across the landscape, and is a tool that could be applied to large-scale invasive species management. Spatial prioritization has been used in several wetland restoration planning studies, in forest restoration, and in riparian and watershed restoration. Spatial prioritization has not been used as extensively in invasive species management, yet there are clear opportunities for spatial prioritization methods to inform invasive species management. Here we apply results from species distribution models to create a prioritization framework for control of the invasive wetland grass common reed, one of the most problematic invasive plants in North American wetlands.

Alien invasive species have strategies that can maintain fitness in a variety of environments. This flexibility is associated with environmental tolerance in several traits, such as allocation of resources to shoots versus roots, clonal versus sexual reproduction, and survival of seedlings. These traits were explored in the chandelier plant (Kalanchoe delagoensis Eckl. & Zeyh.), which has invasive populations in several countries. Light and water tolerance and herbicide treatments were tested on plantlet survival. Plantlet survival in the most extreme cases (full sunlight and no watering) was close to 30%, whereas in less severe conditions (water and shaded), it was close to 100%. Stress conditions triggered the onset of plantlet production from the margin of leaves, which increased clonality. Biomass was allocated primarily to aboveground structures. Although all herbicides resulted in high plantlet mortality (>85%), only 2,4-D and glyphosate+2,4-D amine achieved the maximum recorded mortality a few days after the chemical application. The high tolerance of K. delagoensis plantlets to varying conditions shows that under stress, plantlet production is enhanced as survival of established individuals decreases. Biomass is primarily aboveground, which can potentially alter nitrogen and carbon in poor arid environments, and the proportion of the biomass assigned to belowground roots increased with an increase in sunlight received. Even though the chemical treatments 2,4-D and glyphosate+2,4-D amine have been shown to be the only effective treatments, the 2,4-D treatment may be the most viable (cost+quantity) to reduce the propagation of K. delagoensis. Plantlets have become the main reason for population persistence, partially due to the plant’s environmental tolerance and ability to reproduce asexually in short time periods. Susceptibility of plantlets to the two herbicides presents a means to adequately manage invasions of K. delagoensis in Mexico.

We investigated the use of sheep for controlling the spread of purple loosestrife in a wet meadow in upstate New York from June to August 2008. Changes in the purple loosestrife population and vascular plant community structure were monitored as a function of the grazing of two ewes, “rotated” through four “experimental” paddocks at 2- to 3-d intervals. Comparative data were collected in “reference” paddocks from which sheep were excluded. Purple loosestrife was heavily grazed and most plants did not flower in experimental paddocks. Purple loosestrife cover declined by 40.7% in the experimental paddocks but did not change significantly in the reference paddocks. After grazing, species richness was 20% higher in experimental than reference paddocks.

Basal bark treatments involve the application of concentrated herbicide solution on each individual stem of targeted plants. When applied to stands of invasive plants with high stem densities, basal bark treatments may result in the use of large quantities of herbicide in a given area. The effect of basal bark treatments using a solution of 25% triclopyr herbicide and 75% methylated seed oil was tested on research plots located in six different groves of invasive fig, a densely stemmed, problematic invader of riparian forests in California. The experimental treatments resulted in application rates that were equivalent to 28 to 44 kg ae/ha, greatly in excess of the labeled maximum use rate of 9 kg ae/ha (8 lb/ac). At 175 d after application, soils near the fig trunks contained high levels of triclopyr residues (up to 6.6 ppmw), suggesting that the chemical made its way into soils during this period and was not completely degraded. Although the mortality of native plants transplanted into treated fig groves was low (up to 16%), it was significantly greater than the mortality experienced by native plants transplanted into untreated control sites (0%). Although effective in controlling invasive fig trees (> 99% mortality), the high herbicide application rates from basal bark treatment preclude the use of this treatment in large fig groves. These treatments may be appropriate, however, when fig groves are small or isolated enough to prevent overapplication on a per-area basis. In addition, neither limited basal bark applications of triclopyr (< 40% of stems treated) nor foliar spray treatments of 2% glyphosate were effective control measures. Further investigation is needed on ways to control large invasive fig groves.