Ventenata [Ventenata dubia (Leers) Coss.], an invasive winter annual grass, negatively impacts grassland community composition and function in the Pacific Northwest. Ventenata dubia established in Palouse prairie (PP) and canyon grasslands (CG) of northern Idaho/eastern Washington in the mid-1980s to early 1990s. Understanding and comparing patterns of invasion can elucidate future trends as its range expands. We performed surveys in PP (2012 and 2013) and CG (2018) to assess V. dubia abundance. Specifically, we correlated species richness, Shannon diversity, rank abundance, and indicator species with no, low (<12.5%), and high (>12.5%) V. dubia cover. We used nonmetric multidimensional scaling analysis (NMDS) to visualize species similarities and associations with abiotic variables. In both ecoregions, V. dubia was very common, appearing in nearly 60% of 450 plots. When present, V. dubia cover averaged 26% (±2.3 SE) in PP and 19% (±1.8 SE) in CG. Indigenous plant species richness and diversity were lowest in plots with high V. dubia cover. In CG, this relationship held for nonindigenous species; in PP, nonindigenous plant richness and diversity were higher with high V. dubia cover. Ventenata dubia and other winter annual grasses (Bromus spp., medusahead [Taeniatherum caput-medusae (L.) Nevski]) were moderately associated according to the NMDS analysis. Indicator species analysis showed V. dubia was positively associated with nonindigenous winter annual grasses and negatively associated with indigenous low shrub species. Abiotic factors that explained V. dubia abundance included shallow soils and a south to west aspect. Overall, these findings indicate V. dubia can successfully invade both dry and relatively wet plant communities and is more abundant than other invasive annual grasses. We suggest these findings foreshadow what will happen in sagebrush steppe and Great Plains grasslands, regions where V. dubia recently became established.

Jubatagrass is one of the most invasive plants along the California and southern Oregon coast. It establishes dense populations that can severely impact native plant diversity and conifer seedling recruitment following forestry operations. This goal of this study was to evaluate the effectiveness of both manual removal and several herbicide control options and application techniques. In addition, a cost analysis was also conducted for the most successful herbicide control methods. Results demonstrate that mechanical removal through digging is effective, although labor intensive. Among the herbicides tested, glyphosate applied as a high-volume (spray-to-wet) application (0.6% ae) in early summer, low-volume application (2.4% ae) in early summer or fall, and ropewick technique in early summer or fall (> 9.9% ae) all provided ≥ 88% jubatagrass control, but the low-volume treatments were the most cost effective. Although the graminicide sethoxydim at the highest rate (0.36% ai) did not give effective control, fluazifop applied in the fall in a low-volume treatment (0.98% ai) gave 87% control of jubatagrass. Imazapyr gave some level of control but does not appear to provide an economical option for jubatagrass management. Results of this study demonstrate that in addition to the more conventional methods of mechanical removal and spray-to-wet glyphosate (0.6% ae), control of jubatagrass can also be equally or more effective with low-volume and ropewick applications of glyphosate.

Dalmatian toadflax is listed as a noxious weed in most of the western United States, but control of this species has not been extensively studied in California. Studies in other states show effective control of Dalmatian toadflax with picloram, but this herbicide is not registered for use in California. In addition, reports vary as to the optimal timing for herbicide applications. In this study we evaluated several herbicides with combined foliar and soil-residual activity at two times of application: postsenescence (fall) and rosette (winter to early spring). We applied two series of treatments (2008 and 2009 to 2010) on adjacent sites in high desert scrub of southern California. In the year of treatment and the following year, we evaluated Dalmatian toadflax cover and presence/absence of associated dominant species (≥ 5% cover). Although time of application, treatment, and timing by treatment interaction all produced significant differences in Dalmatian toadflax cover in the 2008 trial, only the high rate of aminocyclopyrachlor (280 g ae ha−1) applied to dormant plants in fall consistently reduced cover through the second year. No treatments at the rosette stage consistently produced 2 yr of control. In 2009 to 2010, treatments were more effective, probably owing to higher precipitation in spring. In both dormant and rosette applications made in 2009 to 2010, aminocyclopyrachlor (140 and 280 g ae ha−1) and aminocyclopyrachlor + chlorsulfuron (140 g ae ha−1 + 53 g ai ha−1) gave second year control; chlorsulfuron at the dormant stage (105 and 158 g ai ha−1) and aminopyralid at the rosette stage (245 g ae ha−1) also gave 2 yr of control. The treatments had only minor effects on grass species. The response of broadleaf species varied among treatments, with aminocyclopyrachlor at the high rate increasing Eriogonum spp., but greatly reducing Asteraceae species. These results provide options for the management of Dalmatian toadflax in California and other western states.

Rangeland health assessment provides qualitative information on ecosystem attributes. Successional management is a conceptual framework that allows managers to link information gathered in rangeland health assessment to ecological processes that need to be repaired to allow vegetation to change in a favorable direction. The objective of this paper is to detail how these two endeavors can be integrated to form a holistic vegetation management framework. The Rangeland Health Assessment procedures described by Pyke et al. (2002) and Pellant et al. (2005) currently are being adopted by land managers across the western United States. Seventeen standard indicators were selected to represent various ecological aspects of ecosystem health. Each of the indicators is rated from extreme to no (slight) departure from the Ecological Site Description and/or the Reference Area(s). Successional management identifies three general drivers of plant community change: site availability, species availability, and species performance, as well as specific ecological processes influencing these drivers. In this paper, we propose and provide examples of a method to link the information collected in rangeland health assessment to the successional management framework. Thus, this method not only allows managers to quantify a point-in-time indication of rangeland health but also allows managers to use this information to decide how various management options might influence vegetation trajectories. We argue that integrating the Rangeland Health Assessment with Successional Management enhances the usefulness of both systems and provides synergistic value to the decision-making process.

Prevention, early detection, rapid response, and prioritization are essential components of effective and cost-efficient invasive plant management. However, successfully implementing these strategies requires the ability to accurately predict the temporal and spatial dynamics of newly/recently detected nonnative species. Why some nonnative species become invasive and the source of variation in lag time between arrival and the onset of invasive expansion are poorly understood. One tool to fill these knowledge gaps is the “invasion curve,” which tracks nonnative species abundance (i.e., area invaded) over time after arrival in a new area. Since invasive species curves rely primarily on records from herbarium collections, we propose that these collections can be used as a springboard to develop a standardized approach to building invasion curves. This would allow researchers to compare the trajectories of nonnative species, improving risk assessment and our ability to recognize potential invasive species and factors contributing to both invasibility and invasiveness. While there have been admirable efforts to produce invasion curves, several barriers exist to their reliable production and standardization. In this paper, we explore the challenges related to the efficient production of these curves for plants using herbarium data and suggest ways in which progress could occur. It is our hope that this will better position herbaria and researchers to aid natural resource managers to prioritize needs, make effective management decisions, and develop targeted prevention and monitoring programs by taking advantage of lag times to implement timely responses.

The purpose of this study was to determine the effect of whole-plant composting on the viability of seeds and other propagules of the invasive plant species waterhyacinth, waterlettuce, hydrilla, and giant reed while producing a valuable compost product. Invasive species were subjected to preliminary germination and growth tests and oven mortality tests to evaluate whether species distribution was via seeds, vegetative propagules, or both, as well as whether the composting process had the potential, through the high temperatures obtained, to kill seeds and other propagules. Germination and growth tests determined the means by which invasive species spread. Oven tests determined the temperatures at which unscarified and scarified seeds and propagules were rendered inviable. Achieving temperatures of at least 57.2 C was necessary within constructed compost piles to effectively kill the plants without the danger of redistribution. In the field, the study successfully developed a large-scale composting operation using invasive plant species as the primary feedstock. Analysis of field-scale composting showed final materials were within satisfactory to ideal levels for samples analyzed by the U.S. Compost Council's Seal of Testing Assurance Program and were, therefore, a valuable compost product.

Miconia (Miconia calvescens DC.) is a tropical tree species from South and Central America that is a highly invasive colonizer of Hawaii's forested watersheds. Elimination of satellite populations is critical to an effective containment strategy, but extreme topography limits accessibility to remote populations by helicopter operations only. Herbicide Ballistic Technology (HBT) is a novel weed control tool designed to pneumatically deliver encapsulated herbicide projectiles. It is capable of accurately treating miconia satellites within a 30 m range in either horizontal or vertical trajectories. Efficacy was examined for the encapsulated herbicide projectiles, each containing 199.4 mg ae triclopyr, when applied to miconia in 5-unit increments. Experimental calibrations of the HBT platform were recorded on a Hughes 500-D helicopter while conducting surveillance operations from November 2010 through October 2011 on the islands of Maui and Kauai. Search efficiency (min ha−1; n = 13, R2 = 0.933, P< 0.001) and target acquisition rate (plants hr−1, n = 13, R2 = 0.926, P< 0.001) displayed positive linear and logarithmic relationships, respectively, to plant target density. The search efficiency equation estimated target acquisition time at 25.1 sec and a minimum surveillance rate of 67.8 s ha−1 when no targets were detected. The maximum target acquisition rate for the HBT platform was estimated at 143 targets hr−1. An average mortality factor of 0.542 was derived from the product of detection efficacy (0.560) and operational treatment efficacy (0.972) in overlapping buffer areas generated from repeated flight segments (n = 5). This population reduction value was used in simulation models to estimate the expected costs for one- and multi-year satellite population control strategies for qualifying options in cost optimization and risk aversion. This is a first report on the performance of an HBT helicopter platform demonstrating the capability for immediate, rapid-response control of new satellite plant detections, while conducting aerial surveillance of incipient miconia populations.

To eradicate a weed invasion, its extent must be delimited and each infestation must be extirpated. Measures for both of these criteria are utilized to assess the progress of current eradication programs targeting mikania vine and limnocharis in northern Australia. The known infested area for each species is less than 5 ha and has remained largely static for the last 3 or more years against a backdrop of refined and enhanced detection methods. This suggests that delimitation has been approached, if not achieved. Different methods of detection have their places, relative to the stage of the program and the spatial distribution of infestations. Although all known infestations of both species are effectively monitored and controlled, ongoing emergence from persistent seed banks limits progress towards the extirpation of infestations to a slow, but measurable, rate.

Flea beetles (Aphthona spp.) were released in the Little Missouri National Grasslands (LMNG) in western North Dakota in 1999 to control leafy spurge. The changes in leafy spurge density and soil seedbank composition were evaluated on two ecological sites 10 yr (2009) after Aphthona spp. release to monitor the effectiveness of the insects on weed control and the associated changes in plant communities. In 2009, leafy spurge stem density averaged 2 and 9 stems m−2 (0.19 to 0.84 ft−2) in the loamy overflow and loamy sites, respectively, compared with 110 and 78 stems m−2, respectively, in 1999. Leafy spurge constituted nearly 67% of the loamy overflow seedbank in 1999, compared with 2% in 2009. In the loamy seedbank, the weed represented nearly 70% in 1999, compared with approximately 15% in 2009. As leafy spurge abundance was reduced, native species richness and seed count increased 10 yr after Aphthona spp. release. Late seral species represented 17% of the loamy overflow seedbank in 2009, an increase from 5% in 1999. However, Kentucky bluegrass, a nontarget weedy species, increased more than 250% in the loamy overflow seedbank. Late seral species were 38% of the loamy seedbank in 2009, compared with 13% in 1999. The number of native species increased from 31 in 1999 to 39 in 2009 in the loamy overflow seedbank, but only changed from 32 to 34 species in the loamy site during the same period. The reestablishment of native species has been slow, but seedbank analysis indicates the number and type of species found before the leafy spurge infestation have increased. Planting native species in selected areas may have reduced the lag time in these species return to the seedbank and reduced invasion from other nondesirable species, such as Kentucky bluegrass.

Successful colonization of newly introduced species is driven by a multitude of factors and is highly dependent on the species. It has long been hypothesized that preadaptation and postestablishment natural selection of introduced species can facilitate their invasion; however, to date, limited research has been dedicated to these theories. In addition, although the correlation between establishment of invasive species and disturbance has been noted and widely studied, the susceptibility of undisturbed habitats to invasion remains unclear. In California, serpentine habitats are severe edaphic environments that have been relatively free of anthropogenic disturbance and nonindigenous species invasions. In this study, we documented the occurrence of the nonindigenous barb goatgrass on serpentine and nonserpentine grasslands in the California Northern Interior Coast Range and the western foothills of the Sierra Nevada Mountains and conducted greenhouse and field experiments to assess the species' degree of adaptation to serpentine soils. Reconnaissance of serpentine intrusions and yearly monitoring suggest that barb goatgrass may grow preferentially on serpentine soil, particularly disturbed serpentine sites. In the greenhouse, for most measures of performance, serpentine populations performed better than nonserpentine populations when grown on serpentine soil. Particularly noteworthy was that serpentine populations had higher root-mass ratios than nonserpentine populations when grown on serpentine soil. In contrast to the greenhouse study, field-grown populations from serpentine and nonserpentine sources performed equally well on nonserpentine; alluvial, disturbed serpentine; and shallow, undisturbed serpentine, although the overall species' performance was diminished on severe serpentine soils. Alarmingly, even in the absence of previous exposure to serpentine, barb goatgrass was capable of establishing and spreading into minimally disturbed sites with strong serpentinitic characteristics.

In the Great Basin of the western United States, expansion of Pinus monophylla (singleleaf piñyon) and Juniperus osteosperma (Utah juniper) out of historic woodlands and into Artemisia spp. (sagebrush) shrubland communities can facilitate the invasion of exotic downy brome (Bromus tectorum) and lead to decreases in ecological and economic values of shrublands. This expansion has, therefore, been the focus of management efforts, including the thinning or removal of trees in areas that were historically shrubland. Our study examined the effects of tree thinning at two sites located in eastern Nevada, near the center of the Great Basin. Such projects can be controversial, so our goal was to estimate and document the ecological effects of low-disturbance tree thinning at these two sites. Both sites were mechanically thinned using a feller-buncher and were aerially seeded with native grasses. Aerial seeding had no apparent effect at either site. The site that had lower tree cover before treatment (Ely, NV) showed an increase in native forbs and a small increase in invasives. The site that initially had very high tree cover and low shrub cover (Mt. Wilson, NV) showed increases in native forbs and species diversity and a substantial increase in invasives. We conclude that low-disturbance methods for thinning encroaching trees can have positive ecological effects in shrublands but that the initial cover of both trees and native herbaceous species should be considered to determine the potential of the site to recover naturally from the seedbank and the risk of invasion by downy brome.

To assess the potential invasiveness of common eucalyptus species planted for pulpwood, mulch wood or bioenergy crops, field surveys of eucalyptus seedling recruitment were conducted in north and central Florida locations within seed bearing eucalyptus stands and in the proximate plant communities where seed dispersal may occur. Plant communities included non-grazed pasture, intensively site-prepared forestland, abandoned forest road and upland mixed pine- hardwood forest. No eucalyptus seedlings were found in any of the 310 1-m2 survey plots across the two locations. Second, seed addition studies were conducted to determine the relative potential for seedling emergence and survival among Eucalyptus amplifolia, E. camaldulensis and E. grandis added into plots at two seed densities, under disturbed and nondisturbed conditions, in the understory of the eucalyptus stands and in each of the aforementioned proximate plant communities. Overall, the probability of emergence of added seed was very low (P = 0.0 to 0.0032), and seed density effects were not significant. Emergence was significantly greater in disturbed conditions compared to nondisturbed conditions for seedlings originating from natural seed rain from the eucalyptus canopy in central Florida. The amount of time that seedlings survived was greater for E. camaldulensis compared to the other species but no seedlings survived more than 13 wk. These data indicate that under specific favorable conditions, eucalyptus seedlings may establish within or proximate to planted stands, but the overall level of invasiveness demonstrated by E. amplifolia and E. grandis is low for north or central Florida. The demonstrated role of disturbance in facilitating eucalyptus seedling recruitment suggests that a stable perennial plant community (native grasses) should be established instead of bare soil buffer zones to mitigate spread.

Dioscorea bulbifera is a serious invader of various ecosystems in Florida, where plants generated by its two morphotypes climb aggressively and smother supporting vegetation. There is a dearth of published research on its invasive biological attributes including vine growth and biomass production by plants generated from bulbils. Herein, we assessed these parameters in common garden studies by planting bulbils from four biomass categories (PBBCs I–IV) of both morphotypes. Vine lengths, longevity-based growth rates (VLGR), biomass, and quantities of leaves and daughter bulbils in both morphotypes showed positive correlation with the biomass of planted parental bulbils. This indicated similarity between corresponding attributes in two morphotypes. Total vine length showed strong positive correlation with VLGR, biomass, and quantities of leaves and bulbils. Overall vine longevity among plants from PBBCs I–IV did not significantly differ whereas the total vine lengths, VLGRs, number of branches, and quantities of leaves and bulbils increased with the biomass of the parental bulbils. Plants recruited by smaller bulbils allocated more biomass to leaves and tubers compared to stems and bulbils, whereas the plants recruited by larger bulbils allocated more biomass to leaves and bulbils compared to tubers and stems. Higher proportion of biomass allocation to leaves and bulbils presumably ensures immediate faster growth, longer vines, and a greater number of daughter bulbils for future recruitment of new plants. Vine length (associated with faster growth rate, capable of blanketing supporting structures and producing large quantities of bulbils) has been noted as the primary invasive biological attribute that facilitates D. bulbifera's status as a noxious exotic weed in Florida. Control measure that can reduce vine length should reduce or eliminate the invasive behavior of D. bulbifera in Florida.

Yellow starthistle (Centaurea solstitialis) is an exotic winter annual forb that is aggressively invasive and problematic in much of California, Idaho, Oregon, and Washington. Yellow starthistle control is particularly challenging in canyon rangelands where accessibility limits control options. Our objective was to evaluate the effects of late-season targeted goat grazing on yellow starthistle and nontarget grasses and forbs. A 3-yr grazing study was initiated in 2006 on a 380-ha (939 acres) canyon grassland site infested with yellow starthistle near White Bird, ID. Twenty-four paired plots were established, with each pair including a fenced subplot to exclude grazing and a similar-sized adjacent subplot that was grazed. Density of yellow starthistle plants and seedheads was assessed after grazing of each plot in all 3 yr and before grazing in the second and third years. Canopy cover of yellow starthistle, grasses, and forbs also was measured. Grazed subplots had 58% fewer yellow starthistle plants than the ungrazed controls after grazing was applied and 94% fewer seedheads after 3 yr of grazing. Cover of yellow starthistle did not differ between grazed and ungrazed subplots after grazing in 2006, whereas grazing decreased yellow starthistle cover in 2007 and 2008 by about 75%. Goat grazing had little impact on canopy cover of grasses and resident forbs, with the exception of after grazing in 2007 when there was less forb cover in grazed areas compared with ungrazed areas. Late-season (i.e., July to November) targeted goat grazing appears to be an effective way to reduce yellow starthistle plant densities at landscape scales, which creates a large window of opportunity for grazing treatment and flexibility for land and livestock managers.

Invasive species are widely recognized as a major threat to global diversity and an important factor associated with global change. Species distribution models (SDMs) have been widely applied to determine the range that invasive species could potentially occupy, but most examples focus on predictive variables at a single spatial scale. In this study, we simultaneously considered a broad range of variables related to climate, topography, land cover, land use, and propagule pressure to predict what areas in the southeastern United States are more susceptible to invasion by 45 invasive terrestrial plant species. Using expert-verified occurrence points from EDDMapS, we modeled invasion susceptibility at 30-m resolution for each species using a maximum entropy (MaxEnt) modeling approach. We then analyzed how environmental predictors affected susceptibility to invasion at different spatial scales. Climatic and land-use variables, especially minimum temperature of coldest month and distance to developed areas, were good predictors of landscape susceptibility to invasion. For most of the species tested, human-disturbed systems such as developed areas and barren lands were more prone to be invaded than areas that experienced minimal human interference. As expected, we found that landscape heterogeneity and the presence of corridors for propagule dispersal significantly increased landscape susceptibility to invasion for most species. However, we also found a number of species for which the susceptibility to invasion increased in landscapes with large core areas and/or less-aggregated patches. These exceptions suggest that even though we found the expected general patterns for susceptibility to invasion among most species, the influence of landscape composition and configuration on invasion risk is species specific.

Throughout the world, the invasion of nonnative plants is an increasing threat to native biodiversity and ecosystem sustainability. Invasion is especially prevalent in areas affected by land transformation and disturbance. Surface mines are a major land transformation, and thus may promote the establishment and persistence of invasive plant communities. Using the Shale Hills region of Alabama as a case study, we assessed the use of landscape characteristics in predicting the probability of occurrence of six invasive plant species: sericea lespedeza, Japanese honeysuckle, Chinese privet, autumn-olive, royal paulownia, and sawtooth oak. Models were generated for invasive species occurrence using logistic regression and maximum entropy methods. The predicted probabilities of species occurrence were applied to the mined landscape to assess the probable prevalence of each species across the landscape. Japanese honeysuckle had the highest probable prevalence on the landscape (48% of the area), with royal paulownia having the lowest (less than 1%). Overall, 67% of the landscape was predicted to have at least one invasive plant species, with 20% of the landscape predicted to have two or more species, and 3% of the landscape predicted to have three or more species. Japanese honeysuckle, sericea lespedeza, privet, and autumn-olive showed higher occurrence on the reclaimed sites than across the broader region. We found that geospatial modeling of these invasive plants at this scale offered potential for management, both for identifying habitat types at risk and areas that need management attention. However, the most immediate action for reducing the prevalence of invasive plants on reclaimed mines is to remove invasive plants from the reclamation planting list. Three (sericea lespedeza, autumn-olive, and sawtooth oak) out of the six most common invasive plants in this study were planted as part of reclamation activities.

The distribution of genetic diversity in invasive plant populations can have important management implications. Alligatorweed [Alternanthera philoxeroides (Mart.) Griseb.] was introduced into the United States around 1900 and has since spread throughout much of the southern United States and California. A successful biological control program was initiated in the late 1960s that reduced A. philoxeroides in the southern United States, although control has varied geographically. The degree to which variation among genotypes may be responsible for variation in control efficacy has not been well studied due to a lack of genetic data. We sampled 373 plants from 90 sites across the United States and genotyped all samples at three chloroplast regions to help inform future management efforts. Consistent with clonal spread, there was high differentiation between sites, yet we found six haplotypes and high haplotype diversity (mean h = 0.48) across states, suggesting this plant has been introduced multiple times. Two of the haplotypes correspond to previously described biotypes that differ in their susceptibility to herbicides and herbivory. The geographic distribution of the three common haplotypes varied by latitude and longitude, while the other haplotypes were widespread or localized to one or a few sites. All the haplotypes we screened are hexaploid (6n = 102), which may enhance biological control. Future studies can use these genetic data to determine whether genotypes differ in their invasiveness or respond differently to control measures. Some states, for instance, have mainly a single haplotype that may respond more uniformly to a single control strategy, whereas other states may require a variety of control strategies. These data will also provide the basis for identifying the source regions in South America, which may lead to the discovery of new biological control agents more closely matched to particular genotypes.

The aim of this study was to evaluate the effect of the macrophyte waterhyacinth on the water quality of a reservoir in Colombia. Postinvasion water quality assessments were performed during three different hydrological periods and compared with preinvasion data. The results show that water quality has improved, especially in terms of transparency, showing an increase in Secchi disk values from 0.3 to 2 m (1 to 6.6 ft). The analysis strongly suggests that the improvement in water quality is due to the filtering and precipitation effects provided by waterhyacinth. This case highlights the dilemma of managing an invasive species that provides a beneficial ecological service while posing a high ecological risk.

Yellow starthistle is the most widespread broadleaf invasive plant in the western United States, and it is particularly prevalent in California. Prior to the registration of aminopyralid in 2005, the standard for chemical control of yellow starthistle was the herbicide clopyralid. We report on a compilation of several independent trials comparing the efficacy of aminopyralid and clopyralid on yellow starthistle. Treatments were applied at several rates and timings at 11 locations in four states between 2001 and 2007. Treatments were made pre-emergence and postemergence at the seedling and rosette stages of yellow starthistle. Results showed that aminopyralid, even at the low rate of 18 g ae ha−1, provided nearly complete control of yellow starthistle when treatments were made at the seedling stage. However, less consistent control (80 to 100%) resulted with applications made at the pre-emergence and rosette stages. At the seedling stage, aminopyralid is about four times more effective on yellow starthistle compared to clopyralid, based on the rate of acid equivalent. In the Central Valley of California, complete control was obtained at the lowest registered rate (53 g ae ha−1) when applications were made from December through February. At two locations we also evaluated control of the poisonous native plant coast fiddleneck. Although clopyralid does not adequately control coast fiddleneck, aminopyralid provided almost complete control when applied in the winter growing season. Applications of aminopyralid at the rosette stage resulted in a two-fold increase in annual forage grass biomass the following year. These results indicate that aminopyralid is a valuable tool for land managers and can play an important role in integrated management strategies for yellow starthistle and coast fiddleneck.

Noncropland such as levees, roadsides, field borders, fencerows, and wildlife areas are vulnerable to weed invasion. Many sites have undergone frequent human disturbance, such as manipulation from surrounding land uses, and lack competitive, desirable vegetation. This study addressed the importance of revegetation in an integrated weed management program including revegetation for noncrop areas. The study evaluated 14 cool-season perennial grasses (seven native species and eight introduced species) for their establishment, vigor, and ability to suppress weeds. It also evaluated the impact of herbicides on weed control and grass establishment. Treatments were applied at three noncrop sites in Northeast California that were heavily infested with weeds. Chemical weed control during the year of seeding and the following year was critical for perennial grass establishment. Weed cover was greater than 50% whereas average seeded grass cover was less than 6% in untreated plots at all sites 2 yr after seeding. In contrast, average seeded grass cover at all sites was 22 to 31% 2 yr after seeding for treatments where herbicide use resulted in wide-spectrum weed control and grass safety. Increasing perennial grass cover decreased total weed cover across perennial grass species 1and 2 yr after seeding. Individual grass species' cover differed among sites. Two introduced grasses (tall wheatgrass and crested wheatgrass) and three native grasses (western wheatgrass, bluebunch wheatgrass, and thickspike wheatgrass) showed broad adaptation and had > 20% cover at all sites 2 yr after seeding. In herbicide-treated plots, these grasses reduced total weed cover by 43 to 98% compared to unseeded plots 2 yr after seeding.