Rapid increases in herbicide resistance have highlighted the ability of weeds to undergo genetic change within a short period of time. That change, in turn, has resulted in an increasing emphasis in weed science on the evolutionary ecology and potential adaptation of weeds to herbicide selection. Here we argue that a similar emphasis would also be invaluable for understanding another challenge that will profoundly alter weed biology: the rapid rise in atmospheric carbon dioxide (CO2) and the associated changes in climate. Our review of the literature suggests that elevated CO2 and climate change will impose strong selection pressures on weeds and that weeds will often have the capacity to respond with rapid adaptive evolution. Based on current data, climate change and rising CO2 levels are likely to alter the evolution of agronomic and invasive weeds, with consequences for distribution, community composition, and herbicide efficacy. In addition, we identify four key areas that represent clear knowledge gaps in weed evolution: (1) differential herbicide resistance in response to a rapidly changing CO2/climate confluence; (2) shifts in the efficacy of biological constraints (e.g., pathogens) and resultant selection shifts in affected weed species; (3) climate-induced phenological shifts in weed distribution, demography, and fitness relative to crop systems; and (4) understanding and characterization of epigenetics and the differential expression of phenotypic plasticity versus evolutionary adaptation. These consequences, in turn, should be of fundamental interest to the weed science community.

Many invasive species managers state that their objective is to “control” an invader. However, the appropriate choice of a management option requires a more explicit statement of management objectives, in terms of both the relevant time horizon and spatial scale. Using data from a 2-yr mowing experiment, we show that the most effective management strategy for controlling an invasive thistle depends fundamentally on the management goals. We integrate field data from a two-cohort experiment with modeling to assess 14 mowing treatments (differing in intensity, frequency, and timing, and thus also in their required logistical effort) based on their effectiveness in (1) reducing population density of the existing cohort, (2) decreasing projected long-term population growth, and (3) limiting projected population spread of an invasive thistle, musk thistle (Carduus nutans L.). The treatment with high intensity and a single late mow caused the largest reduction in plant survival (and density of existing adult plants); the treatment with high intensity and an early mow in addition to a late mow was most effective at reducing population growth rate and population spread. Against expectation and conventional wisdom, the most frequent mowing treatment did not provide the most effective management outcome for any stated objective. This study highlights the necessity of clearly defined management aims; the term “control” is too vague to be truly useful. The results also provide important insights for the management of this invasive species.

Buffelgrass [Pennisetum ciliare (L.) Link] is a drought-tolerant invasive grass that is a threat to native biodiversity in the drylands of the Americas and Australia. Despite efforts from land managers to control P. ciliare, management approaches tend to have mixed success, treatment results can be poorly communicated among entities, and there are few long-term controlled studies. In this literature review, we synthesize data from both peer-reviewed and “gray” literature on the efficacy of management techniques to control P. ciliare and the secondary impacts to native plant communities. Our search resulted in 42 unique sources containing a total of 229 studies that we categorized into 10 treatment types, which included herbicide, seeding, manual removal, fire, grazing, biocontrol, fire + additional treatments, manual removal + additional treatments, herbicide + additional treatments, and herbicide + manual removal. We found that treatments that used multiple techniques in tandem along with follow-up treatments were the most effective at controlling P. ciliare. Fewer than one-third of the studies reported impacts of management on native species, and the most commonly studied treatment (herbicide, N = 130) showed detrimental impacts on native plant communities. However, the average time between treatment and outcome measurement was only 15 mo; we suggest the need for more long-term studies of treatment efficacy and secondary impacts of treatment on the ecosystem. Finally, we conducted a second literature review on P. ciliare biology and traits for mechanisms that allows P. ciliare to alter the invaded environment to facilitate a competitive advantage over native species. We found evidence of self-reinforcing feedbacks of invasion being generated by P. ciliare through its interactions with water availability, nutrient cycling, and disturbance regimes. We developed a conceptual model of P. ciliare based on these feedback loops and offer management considerations based on its invasion dynamics and biology.

Large-scale control of invasive plants can benefit strongly from reliable assessment of spatial variation in plant invasibility. With this knowledge, limited management resources can be concentrated in areas of high invasion risk. We assessed the influence of spatial environments and proximity to roads on the invasibility of African mustard (Brassica tournefortii Gouan) over the 280,000-ha Barry M. Goldwater Range West in southwestern Arizona, USA. We used presence/absence data of B. tournefortii acquired from a vegetation classification project, in which lands were mapped to the level of vegetation subassociations. Logistic regression models suggested that spatial environments represented by the subassociations, not proximity to roads, represented the only factor significantly explaining B. tournefortii presence. We then used the best model to predict B. tournefortii invasibility in each subassociation. This prediction indicates management strategy should differ between the western part and the central to eastern part of the range. The western range is a large spatial continuum with intermediate to high invasion risk, vulnerable to an untethered spread of B. tournefortii. Controlling efforts should focus on preventing existing local populations from further expansion. The central and eastern ranges are a mosaic varying strongly in invasion risk. Control efforts can take advantage of natural invasion barriers and further reduce connectivity through removal of source populations connected with other high-risk locations via roads and other dispersal corridors. We suggest our approach as one effective way to combine vegetation classification and plant invasion assessment to manage complex landscapes over large ranges, especially when this approach is used through an iterative prediction–validation process to achieve adaptive management of invasive plants.

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.

In eastern deciduous forests of North America, invasive shrubs are increasing in richness and abundance at the expense of native species across taxa. Invasive shrubs create an understory that is more dense than both recent and historical preinvasion conditions. Interest in invasive shrub removal to restore native habitat is growing, but our understanding of natural regeneration following treatment of a diverse invasive shrub community is lagging. Using an invasive shrub removal experiment, we provide insight into the effect of repeated removal of a suite of 18 invasive shrub species dominated by border privet (Ligustrum obtusifolium Siebold & Zucc.). In 2009, invasive shrubs were removed from five 20-m-diameter treatment plots, each with a paired control plot. Seven years later, we find an increase in plant diversity, native understory species abundance, and overstory tree species regeneration for individuals under a meter in height. For plants 1 to 4 m in height, the removal treatment has a positive effect on understory woody species, but there has been no change in regenerating overstory trees. A lack of overstory tree regeneration to greater heights is not surprising, given the time frame and the closed-canopy conditions. However, other factors, such as white-tailed deer (Odocoileus virginianus Zimmermann) browse, could be serving as an impediment to taller tree regeneration in the forest understory. An ambient sampling approach in unmanaged, invaded, and uninvaded forest has been used in other studies to estimate the potential impacts of invasive shrub species to native plant communities. However, in this study the ambient sampling approach underestimated the impacts of invasive shrubs compared to their experimental removal. Overall, invasive shrub removal increased plant diversity and allowed passive natural regeneration of native plants that exceeded native cover in the unmanaged, ambient forest under minimal invasive shrub abundance.

Lesser celandine (Ficaria verna Huds.), an invasive plant from Europe, is becoming widespread in river valleys throughout the northeastern United States and the Pacific Northwest. Its high rate of asexual bulbil and tuber production creates dense infestations threatening native spring ephemerals. Ficaria verna abundance and reproductive output (seeds, bulbils, and tubers) were examined in invaded transects spanning a disturbance gradient away from a river. Site characteristics (photosynthetically active radiation [PAR], soil pH, moisture, texture, and nutrients) were quantified to examine their roles in plant abundance and reproduction. A larger-scale study examined random transects not specifically chosen based on F. verna infestations. Soil characteristics and slope were hypothesized to drive F. verna abundance and reproduction; we also hypothesized that reproductive output and biomass would be highest at intermediate distances from rivers, where disturbances are infrequent. Ficaria verna abundance and reproductive output varied considerably by site; soil characteristics, rather than landscape placement, appeared to drive plant abundance and reproduction. Lower percent sand was associated with significantly higher F. verna stem density and bulbil and tuber production. CEC was significantly negatively related to F. verna biomass and tuber counts. In the larger-scale survey, slope and PAR were significantly negatively related to F. verna presence and percent cover, respectively. Overall, these findings suggest that soil texture and slope can help explain higher abundance and reproductive outputs. However, reproductive output and biomass were not significantly greater at intermediate distances, contrary to expectations. We did not observe any seed production in any of the plots, although we did see a few plants with seeds outside our study area in the second year, demonstrating a near-complete reliance on asexual reproduction in these populations. This study expands on the current limited understanding of F. verna and can help management by identifying areas likely to support dense infestations.

Ventenata [Ventenata dubia (Leers) Cross] is a winter annual grass relatively new to the inland Pacific Northwest that is capable of displacing desired vegetation. Indaziflam was evaluated for the management of V. dubia on two Conservation Reserve Program (CRP) sites near Moscow, ID, and Pullman, WA. While perennial grasses were dormant, applications of indaziflam in mixture with various herbicides were made in spring 2016. Treatment effects were evaluated for 2 yr by visual assessments of community composition and canopy cover of V. dubia and other non-weedy species (assessments occurred 3 to 6 mo after treatment, depending on location) and by representative cover class assessments. Biomass samples of all plant species were collected in the summer of 2017. Reduced V. dubia cover was observed in 2016, except when glyphosate was used alone. In 2017 indaziflam applied alone or in mixture with rimsulfuron effectively controlled V. dubia with minimal impact on desirable vegetation. Plant biomass from nontreated plots averaged 40 g m−2 for V. dubia and 100 to 179 g m−2 for perennial grasses. Plant biomass averaged <11 g m−2 for V. dubia and 371 to 490 g m−2 for perennial grasses when indaziflam at 102 g ai ha−1 plus glyphosate at 474 g ai ha−1 was applied. Smooth brome (Bromus inermis Leyss.) biomass was positively associated with the reduction of V. dubia, and there was a decrease in diversity associated with the removal of V. dubia through effective treatments. Indaziflam is an effective tool for the management of V. dubia in perennial grass stands, and spring applications of indaziflam should be in mixture with herbicides with POST activity.

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.

Pale swallowwort (Vincetoxicum rossicum), as well as its congener, black swallowwort (Vincetoxicum nigrum), is a European viny milkweed that has become invasive in natural areas and perennial cropping systems in the northeastern and midwestern United States and southeastern Canada. Mechanical control over 1 to 2 yr has not been effective, but studies of a longer duration are needed. We measured effects of mowing (no mowing or three or six times per growing season) on stem and root crown densities, percent cover, and follicle (seed pod) production of V. rossicum and percent cover of other vegetation over a 7-yr period. Stem density, root crown density, and percent cover of V. rossicum were reduced after 3 to 5 yr of mowing regardless of mowing frequency. Cover of other, mostly nonnative, broadleaf species increased. Follicle production was eliminated in all years of the study. In our environment, mowing three times at monthly intervals during the growing season can prevent seed production. However, mowing must occur for at least 3 yr to reduce, but not eliminate, stands of V. rossicum.

Selective browsing by abundant, generalist herbivores on preferred species could allow less-preferred invasive species to flourish. We tested such an effect by examining rates at which white-tailed deer (Odocoileus virginianus Zimmermann) consume Amur honeysuckle [Lonicera maackii (Rupr.) Herder], an invasive shrub, relative to native woody species across eight forested sites in southwestern Ohio. We tested three hypotheses: (1) deer prefer to browse on L. maackii versus other woody plants; (2) L. maackii is not a preferred source of browse, but is consumed where preferred foods are scarce; and (3) L. maackii provides an important food resource for deer in early spring when other foods are scarce. We used counts of browsed and unbrowsed twigs of each species to calculate, for each site, both the proportion of each species’ twigs browsed and the degree to which deer selectively favor each species (“electivity”) during early to mid-growing season. Across the eight sites, electivity of L. maackii correlated with the proportion of its twigs browsed, and both measures were negatively associated with the density of L. maackii twigs. Lonicera maackii electivity was negative at most sites, indicating it is generally not preferred, undermining hypothesis 1. The hypothesis that deer consume L. maackii when more-preferred foods are depleted was not supported, as there was no negative relationship between L. maackii browse and the density of twigs of more-preferred species. We found a negative relationship between the proportion of L. maackii twigs browsed and the density of L. maackii among sites, which supports the third hypothesis. This finding, combined with seasonal patterns of deer browse on L. maackii, indicates that this invasive shrub is an important source of browse for deer during early spring, regardless of its abundance.

In California, invasive grasses have displaced native plants, transforming much of the endemic coastal sage scrub (CSS) to nonnative grasslands. This has occurred for several reasons, including increased competitive ability of invasive grasses and long-term alterations to the soil environment, called legacy effects. Despite the magnitude of this problem, however, it is not well understood how these legacy effects have altered the soil microbial community and, indirectly, native plant restoration. We assessed the microbial composition of soils collected from an uninvaded CSS community (uninvaded soil) and a nearby 10-ha site from which the invasive grass Harding grass (Phalaris aquatica L.) was removed after 11 yr of growth (postinvasive soil). We also measured the survival rate, biomass, and length of three CSS species and P. aquatica grown in both soil types (uninvaded and postinvasive). Our findings indicate that P. aquatica may create microbial legacy effects in the soil that likely cause soil conditions inhibitory to the survival rate, biomass, and length of coastal sagebrush, but not the other two native plant species. Specifically, coastal sagebrush growth was lower in the postinvasive soil, which had more Bacteroidetes, Proteobacteria, Agrobacterium, Bradyrhizobium, Rhizobium (R. leguminosarum), Candidatus koribacter, Candidatus solibacter, and rhizophilic arbuscular mycorrhizal fungi, and fewer Planctomycetes, Acidobacteria, Nitrospira, and Rubrobacter compared with the uninvaded soil. Shifts in soil microbial community composition such as these can have important implications for restoration strategies in postinvasive sites.

Hen’s eyes (Ardisia crenata Sims) is a shade-tolerant invasive shrub displacing native understory in forests of the Coastal Plain of the southeastern United States. Few studies have explored herbicide effectiveness on A. crenata, with foliar applications of triclopyr amine or triclopyr ester typically referenced as the standard treatments. This study evaluated efficacy of eight foliar herbicide treatments and a nontreated check at three locations at 12 mo after the first treatment (12MAT1) and 12 mo after the second treatment (12MAT2) on established (greater than 8-cm high) and seedling (less than 8-cm high) A. crenata. Treatments were four triclopyr formulations: amine, ester, choline, and acid (all at 4.04 kg ae ha−1); imazamox (1.12 and 2.24 kg ae ha−1); flumioxazin (0.43 kg ai ha−1); and triclopyr amine plus flumioxazin (4.04 + 0.43 kg ae ha−1). At 12MAT1, triclopyr ester, the high rate of imazamox, and triclopyr acid resulted in greater control of established A. crenata than any other herbicide (68%, 66%, and 64%, respectively). At 12MAT2, all herbicides except flumioxazin resulted in some control of A. crenata. Triclopyr ester, triclopyr acid, and the high rate of imazamox provided 95%, 93%, and 92% control, respectively. Triclopyr choline did not perform as well as the acid or ester formulations, and the tank mix of flumioxazin and triclopyr amine did not improve control over triclopyr amine alone. This study identified triclopyr acid and imazamox (2.24 kg ae ha−1) as new options for A. crenata control and indicated variation in the performance among the four triclopyr formulations.

Invasive shrubs like Tamarix spp. are ecological and economic threats in the U.S. Southwest and West, as they displace native vegetation and require innovative management approaches. Tamarix control typically consists of chemical and mechanical removal, but these methods may have negative ecological and economic impacts. Tamarisk leaf beetles (Diorhabda spp.) released for biocontrol are becoming increasingly established within Western river systems and can provide additional control. Previous Diorhabda research studied integration of beetle herbivory with fire and with mechanical management methods and herbicide application (e.g., cut stump), but little research has been conducted on integration with mowing and foliar herbicide application, which cause minimal soil disturbance. At Caballo Reservoir in southern New Mexico, we addressed the question: “How does Tamarix respond to chemical and mechanical control when Diorhabda is well established at a site?” A field experiment was conducted by integrating mowing and foliar imazapyr herbicide at standard (3.6 g ae L−1 [0.75% v/v] and low (1.2 g ae L−1 [0.25% v/v]) rates with herbivory. Treatments were replicated five times at two sites—a dry site and a seasonally flooded site. Beetles and larvae were counted and green foliage was measured over 2 yr. Mowing and full herbicide rates reduced green foliage and limited regrowth compared with low herbicide rate and beetles alone. Integrating conventional management such as mowing and herbicide with biocontrol could improve Tamarix management by providing stresses in addition to herbivory alone.

Downy brome (Bromus tectorum L.) is a common impediment to ecological restoration, because its seedbank remains viable after repeated treatment with herbicides. Soil solarization has been used in ecological restoration to control seedbanks of invasive plants. Here we test the efficacy of soil solarization to reduce B. tectorum cover and establish native plants at a site in B. tectorum’s core invasive range with a long history of disturbance and infestation. Solarization raised soil temperatures by as much as 13 C and reduced B. tectorum densities by approximately 20-fold. In 30 plots solarized for 0 to 101 d, B. tectorum emerged in inverse abundance to treatment duration. Broadleaf weeds were less abundant than B. tectorum before treatment, and diminished under solarization, but their response to solarization was weaker than B. tectorum’s, and they emerged in greater numbers than B. tectorum 2 to 3 yr after treatment. When seeded after solarization, a native perennial bunchgrass, squirreltail [Elymus elymoides (Raf.) Swezey], did not differ in abundance between solarized and control plots. Solarization may facilitate B. tectorum control on a small scale without jeopardizing the establishment of native plants, but only if treatment durations are long and subsequent management of broadleaf weeds and remnant B. tectorum is planned.

Little is known about impacts of soilborne pathogen legacies on reestablishment of native plant species in abandoned agricultural fields. We tested whether pathogens found in abandoned citrus orchards affect growth of native and invasive plant species in a controlled greenhouse experiment. In previous research, we identified several species of ascomycete (Fusarium spp.) and oomycete (Pythium spp.) pathogens from field roots and soils. The invasive annual grass, ripgut brome [Bromus diandrus (Roth.)], and native forbs, common fiddleneck [Amsinckia intermedia Fisch. & C.A. Mey.], coastal tidytips [Layia platyglossa (Fisch. & C.A. Mey.) A. Gray], and California goldfields [Lasthenia californica (DC. ex Lindl.)], were grown together in four different field soil treatments. Using pesticides on soils collected from abandoned citrus fields, we created four soil treatments that excluded different groups of potential pathogens: (1) untreated control (2) metalaxyl (oomyceticide) (3) fludioxonil (fungicide), and (4) steam-sterilized. Fludioxonil increased aboveground biomass of L. platyglossa (P = 0.005) and L. californica (P= 0.02) compared with sterile and metalaxyl-treated soils. Lasthenia californica had decreased arbuscular mycorrhizal colonization with metalaxyl, suggesting metalaxyl has non-target effects on mycorrhizae. Fludioxonil decreased potential pathogens in L. californica roots while having no effect on mycorrhizal colonization. Bromus diandrus had higher biomass in sterile and fludioxonil-treated soils than untreated soils (P = 0.0001), suggesting a release from soilborne pathogens. The release from soilborne pathogens with the use of fludioxonil in both native forbs and B. diandrus, combined with overall higher biomass across treatments in B. diandrus, suggests that pathogen impacts in a field setting are insufficient to reduce success of this invasive grass, and use of a fungicide would not benefit native species in mixed stands with B. diandrus.

Essential variables to consider for an efficient control strategy for invasive plants include dispersion pattern (i.e., satellite or invasion front) and patch expansion rate. These variables were demonstrated for buffelgrass [Pennisetum ciliare (L.) Link], a C4 perennial grass introduced from Africa, which has invaded broadly around the world. The study site was along a roadway in southern Arizona (USA). The P. ciliare plant distributions show the pattern of clumping associated with the satellite (nascent foci) colonization pattern (average nearest neighbor test, z-score −47.2, P<0.01). The distance between patches ranged from 0.743 to 12.8 km, with an average distance between patches of 5.6 km. Median patch expansion rate was 271% over the 3-yr monitoring period versus 136% found in other studies of established P. ciliare patches. Targeting P. ciliare satellite patches as a control strategy may exponentially reduce the areal doubling time, while targeting the largest patches may have less effect on the invasion speed.

Flowering rush (Butomus umbellatus L.) is an invasive aquatic and wetland plant capable of developing monotypic stands in emergent and submersed sites. This plant can rapidly outcompete native vegetation and impede human practices by reducing recreation (boating, fishing, and skiing) and disrupting agricultural use of water resources (irrigation canals). Mechanical removal practices occurring biweekly, monthly, bimonthly, and once per growing season were compared with chemical control with diquat applied sequentially at 0.19 ppmv ai for two consecutive months over 2 yr (2016 and 2017). Biweekly removal gave the most consistent control of B. umbellatus biomass and propagules. Diquat application along with monthly and bimonthly clippings gave varying degrees of B. umbellatus control. Clipping once per growing season did not control B. umbellatus when compared with reference plants, while clipping B. umbellatus every 2 wk (biweekly) controlled rush propagules most effectively. However, it is unlikely this method will be sufficient as a stand-alone control option due to the slow speed of harvester boats, the potential these boats have to spread B. umbellatus propagules to more sites, and the expense of mechanical operations. However, clipping could be used as part of an integrated strategy for B. umbellatus control.

Burmareed [Neyraudia reynaudiana (Kunth) Keng ex Hitchc.] is an aggressive invader of pine rockland communities in south Florida. Currently, it is managed by clipping the stems and later returning, when plants have regrown to approximately 50 cm in height, to administer applications of glyphosate to new foliar growth (a “cut–return–treat,” or CRT, strategy). This multi-visit strategy is time-consuming and may result in off-target effects due to the broad-spectrum nature of glyphosate. With this study we evaluated a cut-stem (CS) approach, in which stems are cut and immediately treated with herbicide. Further, we tested the efficacy of the selective graminicides sethoxydim and fluazifop-P-butyl. In a pot study, CS treatments included: glyphosate (239.7 g ae L−1) in water, sethoxydim (9.0 g ai L−1) or fluazifop-P-butyl (12.1 g ai L−1) in either basal oil or water, and triclopyr (47.9 g ae L−1) in basal oil. All CS treatments provided mortality and growth reduction comparable to the best CRT treatments (glyphosate, sethoxydim, and fluazifop-P-butyl) and were therefore evaluated under field conditions using the same application rates. Mortality was low in the field (≤30%) regardless of herbicide treatment. Overall, fluazifop-P-butyl provided greater control than sethoxydim, resulting in 71% and 94% relative growth reduction in total shoot length with oil and water carriers, respectively, compared with 50% and 43% reduction for sethoxydim. Fluazifop also provided control similar to triclopyr and glyphosate (≥65% reduction in total shoot length). Results suggest that CS treatments may be a viable strategy for managing N. reynaudiana and reducing management costs. However, more research is needed to optimize rates. Further, fluazifop-P-butyl allows for a more selective option than glyphosate that may decrease off-target effects on native understory vegetation in pine rocklands.