Biochar, a carbon-rich product formed by the incomplete combustion of biomass, has been shown to improve soil quality and increase crop growth but has not been evaluated in prairie ecosystems. We assessed the response of a native perennial grass, big bluestem, and an invasive herbaceous perennial, sericea, to biochar amendments in two greenhouse experiments in 2010 and 2011. In the first experiment, big bluestem and sericea were grown in monoculture; the main treatments were soil type (silt, sand), percent biochar (0%, 1%, 2%, and 4%) and nitrogen (0 and 10 g N m⁻²). Big bluestem growth was increased by the addition of biochar, particularly in the sand soil. In contrast, sericea growth was either not affected or decreased when biochar was added to the soil, particularly at the higher biochar rates. Adding N to the soil appeared to increase sericea growth in the presence of biochar and the silt soil, which suggests that biochar may have reduced N availability. A replacement series was used in the second experiment to evaluate the effect of biochar on competition between the two species. Main treatments were biochar rates (0% and 2%), nitrogen rates (0 and 10 g N m⁻²) and the following big bluestem to sericea ratios: 6 ∶ 0, 4 ∶ 2, 3 ∶ 3, 2 ∶ 4, and 0 ∶ 6. After 180 d, big bluestem height and biomass were significantly greater in biochar-amended soils than in unamended soils. However, sericea height and biomass were unaffected by biochar amendments and the addition of biochar did not alter competitive outcomes. Competition between big bluestem and sericea was asymmetrical; sericea reduced the growth of big bluestem but big bluestem had relatively little effect on the growth of sericea. Our research suggests that biochar has the potential to increase the growth of big bluestem and may be a useful tool for prairie restoration.

Nomenclature: Big bluestem, Andropogon gerardii Vitman, sericea, Lespedeza cuneata (Dumont) G. Don.

Management Implications: Sericea is an important weed in prairie and grassland systems in North America. The use of biochar as a soil amendment has the potential to improve the growth of big bluestem and may limit sericea growth in some soils. However, our research suggests that sericea is much more competitive than big bluestem and that biochar amendments alone may not be sufficient to alter competitive outcomes between these two species.

Japanese knotweed and congeners are invasive to North America and Europe and spread aggressively along rivers establishing dense monotypic stands, thereby reducing native riparian plant diversity, structure, and function. Noxious weed control programs attempt to eradicate the knotweed with repeated herbicide applications under the assumption that the system will recover to a native assemblage which will inhibit future invasions. However, eradication efficacy studies typically only measure the amount of knotweed reduced, not the reestablished species diversity or plant origins. For a community scale efficacy study, we measured vascular plant species diversity and cover in riparian areas along five rivers in Washington State, 3 to 6 years after Bohemian knotweed was initially treated with herbicide. Plant species composition was compared between riparian sites treated to remove knotweed and reference sites where knotweed was absent. Sites where knotweed had been removed had significantly more exotic species and vegetative cover than reference sites; however, native species richness and cover were greater in reference sites and areas with more overstory vegetation. The native plants observed were primarily shade tolerant and perennial, as opposed to many of the exotics, which were shade-intolerant annuals. In general, reestablishment of native and exotic vegetation was not related to pretreatment knotweed stem count, size of the invaded area, or timing of herbicide application. However, residual native tree cover was negatively correlated with initial knotweed stem count. Monitoring the success of restoration objectives (e.g., native plant reestablishment or increased species diversity) and characterizing associated habitat features following knotweed eradication will help in the development of site-specific protocols for successful plant community scale restoration.

Nomenclature: Glyphosate, imazapyr, Bohemian knotweed, Polygonum x bohemicum Zika & Jacobson, Japanese knotweed, Polygonum cuspidatum L. Sieb. & Zucc. POLCU.

Management Implications: Foliar herbicide applications successfully reduced the cover of invasive knotweed; however, treatment effects on riparian plant assemblages from passive reestablishment were mixed and depended on site habitat conditions and stream size. Along smaller streams, 2nd to 3rd order, the post-treatment plant assemblages were primarily native in composition, although exotic species were more abundant in the knotweed-treated areas compared to reference (no knotweed) areas. The removal of knotweed cleared sites for colonization by native plants, but also released nontarget exotic invaders. In contrast, riparian areas along the largest stream (4^th order) contained more exotic forbs and shrubs than native plants in both the knotweed-treated and reference sites. The larger stream had riparian areas with little canopy cover and extensive gravel bars and wide floodplains that are subject to higher levels of seasonal flooding. These conditions promote exotic propagule movement and survival.

Successful reestablishment of native vegetation following knotweed removal along large, complex rivers may require active restoration, such as the control of secondary invasions by other exotic plants or replanting native species as conditions change over time. Noxious weed control programs can benefit from including post-treatment plant community surveys, in addition to measuring the amount of the target weed species reduced, to determine if continued management is needed to achieve restoration objectives.

The interactive effects of herbivory, exotic species, and other human-mediated changes to the biosphere are reducing species diversity and altering ecosystem services globally. In this study, we tested whether facilitation could be used as a management technique to restore a degraded northeast Wisconsin forest understory facing high white-tailed deer (Odocoileus virginianus) browse pressure and high abundance of the exotic herb garlic mustard [Alliaria petiolata (Bieb.) Cavara & Grande]. Specifically, we attempted to facilitate native understory restoration by planting or seeding native herbs into three different matrix densities of the native, browse-tolerant grass Virginia wildrye (Elymus virginicus L.), which were either protected from (fenced), or accessible to, deer browsing. Deer had minimal impacts on E. virginicus but significantly reduced the cover, survival, and flower production of white snakeroot [Ageratina altissima (L.) King & H.E. Robins.] transplants, largely independent of the density of E. virginicus plantings in open-access plots. In contrast, the richness and abundance of native-seeded species were not affected by deer access but were reduced by increasing E. virginicus densities. Alliaria petiolata cover was significantly higher in plots accessible to deer but declined significantly with increasing E. virginicus planting density in both open-access and fenced plots. These results were largely corroborated by results from an associated observational study, with the exception that natural E. virginicus stands supported slightly higher native-species richness than did adjacent areas lacking E. virginicus. Thus, although we found little support that establishing E. virginicus facilitated browse-susceptible native understory herbs during our short-term experimental study, restored E. virginicus successfully established, thereby increasing native species cover and significantly reducing the cover of the exotic A. petiolata. We suggest the planting of browse-tolerant native species, such as E. virginicus, as a viable restoration technique in heavily browsed, A. petiolata–invaded woodlands.

Nomenclature: Garlic mustard, Alliaria petiolata (Bieb.) Cavara & Grande, Virginia wildrye, Elymus virginicus L., white snakeroot, Ageratina altissima (L.) King & H.E. Robins

Management Implications: Ecological theory should be used as the basis for developing low-cost, self-perpetuating, restoration techniques that delay, halt, or counter local biodiversity declines and exotic plant invasions. In this study, we investigated the potential for transplanting an unpalatable native grass into an overbrowsed, invaded understory in northeast Wisconsin to facilitate increases in native plant richness and cover and to simultaneously reduce the abundance of the exotic herb garlic mustard (Alliaria petiolata). As expected, the native grass successfully tolerated white-tailed deer browsing, increasing overall native plant cover and significantly reducing A. petiolata cover. In fact, the density of our highest native-grass planting completely offset the seemingly stimulatory effects of white-tailed deer on A. petiolata cover. However, we found little to no support that establishing the native grass promoted increases by other native species. Nevertheless, our results suggest a promising avenue for invasive species management, where restoration goals may often better align with ecosystem stabilization or exotic remission than they do with full ecosystem recovery. Native grass seed and transplants are relatively cheap and, thus, could be economically applied throughout large areas. Should the trends we report be maintained, establishing native grasses may also serve as a sustainable approach f

Vegetation that becomes overtopped usually experiences a decrease in abundance or species richness. When an overtopping plant alters the physiognomy of the existing vegetation (e.g., trees invading a shrubland), ecosystem processes can also be dramatically altered. Worldwide, Monterey pine (Pinus radiata) cultivars have been planted in Mediterranean-like climates and are known to invade surrounding natural communities. Ecological impacts resulting from these invasions have been widely investigated; however, the effects from solitary pine trees on the vegetation they overtop are lacking. Furthermore, studies on the impact of P. radiata cultivars from the California floristic province, where P. radiata is native, do not exist. In coastal California, north of the present-day range of native P. radiata stands, cultivars of this species have invaded northern coastal scrub vegetation. To determine the impact of pine invasion on species richness and structure in this habitat, floristic surveys were conducted in 20 blocks that consisted of invaded and uninvaded plots. An invaded plot contained two subplots located under the canopy of an isolated pine tree, whereas a paired, uninvaded plot contained two subplots located in coastal scrub adjacent to each pine. Pine trees selected ranged in size from 2.8 to 119 cm (1.1 to 46.9 in) basal diameter. Our results demonstrate that understory native cover and species richness are negatively correlated with tree size. Understory exotic plant cover and richness of species other than P. radiata did not show any correlation with tree size, mainly because exotic plants had a very low abundance overall.

Nomenclature: Monterey pine, Pinus radiata D. Don

Management Implications: It is not surprising that large, invading trees would affect or alter the vegetation of treeless communities. Understanding what types of changes are taking place is critical for determining how and when invasive tree removal or other types of management practices should be implemented. Based on our results, to minimize the negative effects of invading trees on native plant cover and species richness in coastal scrub habitat, invasive trees should be removed as early in their stage of growth as possible. Furthermore, removing invasive trees before they become reproductively mature can also help control their spread, although this was not a focus of our study. In our study, we demonstrate how the effect of an invasive tree species can be understood from just one point in time by sampling the understory of several different-sized trees. Pinus radiata is one of the most widely planted trees in the world, so these findings and methods may be helpful to a broad audience and applicable to other invaded habitat types, although the ecological impacts of this species could be different in other parts of the world. These methods may also be useful for studying the effects of invasive tree species in general. In our study area, one of the management objectives is to preserve the mosaic of coastal scrub and grasslands that are habitat for numerous special-status species. Therefore, understanding how the primary vegetation type (coastal scrub) is altered by an exotic tree can provide justification for spending resources on control methods. Although there is compelling evidence that the invasive pines in our study area are derived from cultivars bred for commercial purposes, additional genetic work from the study area should be done to confirm that assessment. We argue that cultivated P. radiata with an unknown origin would be ill-suited for in situ conservation of native P. radiata or for use as neonative populations. There also could be significant differences in how cultivars vs. native strains of P. radiata behave (growth rate, fitness, ability to spread with and without fire cues, among ot

The intent of this study was to determine if composting is an effective means of managing water hyacinth while producing a quality horticultural compost product. Preliminary tests for the study included germination and seed mortality tests. Germination tests found that water hyacinth seeds germinated on filter paper media soaked in distilled water while placed in petri dishes held at a constant temperature of 27 C for 14 d. Seed mortality test results found that seeds of water hyacinth were rendered inviable at temperatures equal to or above 57 C. The study successfully developed a large-scale composting system that used water hyacinth as a primary feedstock. Eleven compost piles were derived from 10,000 kg of water hyacinth, 9,000 kg of food waste, 11,300 kg of poultry litter, and 17,200 kg of wood chips. Results indicated that the composting process reached and sustained sufficiently high enough temperatures to inactivate and fully decompose seeds and other propagules of water hyacinth. Therefore, water hyacinth can be composted without the potential danger of it spreading. Compost quality tests found that the compost produced was within acceptable to ideal ranges of accepted industry quality standards, though there was a learning curve by student workers in the preparation of the piles using the large equipment.

Nomenclature: Water hyacinth; Eichhornia crassipes (Mart.) Solms

Management Implications: Water hyacinth (Eichhornia crassipes) is one of the most invasive aquatic species worldwide. It became a nationwide aquatic weed problem during the last century after its introduction to the United States in 1884 at the Centennial Exposition in New). Different means of management have been implemented in the past including herbicides and harvesting for various reasons. The plant has been successfully composted in the past, but a large scale system had not been investigated to determine if all plant propagules are destroyed in the process. The intent of this study was to determine if composting is an effective means of managing water hyacinth while producing a quality compost product for the horticultural industry. In this study, over 10,000 kg of water hyacinth, 11,300 kg of poultry litter, and 9,000 kg of cafeteria food waste were collected and mixed with wood chips in a large scale composting system. Seed mortality tests indicated that water hyacinth seed was rendered inviable at temperatures above 57 C and, therefore, field compost piles were maintained at that temperature or above. Sampling for seed from curing piles found that no seeds survived nor were present after the composting process. Compost quality tests conducted by Pennsylvania State Agricultural Analytical Services Laboratory showed that compost produced was equal to or above quality standards. An estimated 50.5 m³ of compost valued at $1,980 was created from materials that were otherwise considered problematic. Therefore, this study found that there is the potential to produce a valuable agricultural or horticultural product from composting invasive weeds while helping to manage populations of invasive species in the environment. Future studies should examine the economic feasibility of the project.

Nonnative Spartina species (cordgrasses) are widely distributed along the West Coast of North America, but have not invaded all bays with susceptible habitat. We used drift cards to assess the patterns and rates of potential Spartina propagule dispersal by ocean currents from estuaries with significant populations of one or more Spartina species. Cards were released monthly for 1 yr from Willapa Bay, Washington; Humboldt Bay, California; and San Francisco Bay, California; with recovery information reported by volunteers. Recovery rates averaged 37% for all release sites. Cards were commonly recovered close to their bay of release but were repeatedly found hundreds of kilometers both north and south of their release location. Cards most generally traveled northward from the release sites. Cards from Humboldt and Willapa bays were commonly recovered along the British Columbia coast, particularly in the winter. Cards released from Humboldt Bay were found farthest from their release sites. One card from Humboldt Bay traveled 2,800 km to Kodiak Island, Alaska. The timing of seed production, combined with prevailing currents, puts bays currently uninfested by Spartina at risk of repeated propagule loading by ocean currents. A coordinated coast-wide strategy for eradication of all nonnative Spartina will be critical to the success of individual bay-wide eradication efforts.

Nomenclature: Common cordgrass, Spartina anglica C. E. Hubbard, dense-flowered cordgrass, Spartina densiflora Brongn., saltmeadow cordgrass, Spartina patens (Ait.) Muhl., smooth cordgrass, Spartina alterniflora Loisel

Management Implications: Nonnative estuarine cordgrasses (Spartina spp.) are invasive weeds of saltmarshes and open mudflats in many bays and estuaries of North America, Australia, China, India, New Zealand, and numerous European countries. In North America the largest core infestations established along the Pacific Coast during the last 150 yr at Willapa Bay, Washington; Humboldt Bay, California; and San Francisco Bay, California. Estuarine plants such as Spartina can disperse to new bays when propagule-laden wrack mats consisting of senescent stems are washed out to the ocean and then drift with the currents. Understanding this natural dispersal mechanism is critical to the success of a coast-wide Spartina eradication strategy because there is a high likelihood of secondary spread from existing infestations—especially those with large historic propagule production. Indeed, a marked increase in novel satellite populations in the last 12 yr suggests spread to new habitats is increasing. This study provides the first examination of the dispersal potential for weedy plant species within the near-shore ocean environment from these three estuaries. The recovery patterns of drift cards, released monthly over the course of 1 yr underscore increased propagule loading at areas proximal to existing infestations, but also highlight the ability of ocean currents to carry seeds great distances, well within known propagule viability ranges. Drift card recoveries spanned 2,044 km north and south of Willapa Bay, 3,304 km north and south of Humboldt Bay, and 661 km north and south of San Francisco Bay. The scope of potential ocean dispersal presented here reinforces the need for effective eradication programs in propagule source areas of not only Spartina spp., but also other weeds that can disperse along this same pathway such as dwarf eelgrass (Zostera japonica), perennial pepperweed (Lepidium latifolium), and Algerian sea lavender (Limonium ramosissimum).

Macartney rose is an aggressive thorny shrub that displaces forage species and hinders cattle grazing in rangelands and pastures of the southern United States. Historically, Macartney rose has proven to be extremely difficult to control even with high rates of soil residual herbicides such as picloram. Recent advances in herbicide chemistry warrant testing on this troublesome species. We compared mowing and late summer broadcast applications of thirteen herbicide treatments that included combinations of aminopyralid, fluroxypyr, metsulfuron, picloram, triclopyr, and 2,4-D. Treatments were applied to the same rose clumps for 2 consecutive yr. An additional mowing was done to one half of the rose clumps in each treatment 6 mo after the second herbicide treatment. At 11 mo after initial treatment (MAIT), mowing and all herbicide treatments performed very poorly and provided 35% control or less. At 12 mo after retreatment (24 MAIT), picloram 2,4-D and aminopyralid metsulfuron, both followed by mowing, were the most effective treatments, providing 72 to 91% control. All other treatments provided less than 70% control. However, complete clump mortality was very low across all treatments, ranging from 3 to 32%. These results indicate that Macartney rose suppression is possible with certain new herbicides, but complete clump kill is still lacking.

Nomenclature: Aminopyralid, fluroxypyr, metsulfuron, picloram, triclopyr, 2,4-D, Macartney rose, Rosa bracteata J. C. Wendl. ROSBC

Management Implications: Macartney rose is one of the most difficult-to-control thorny shrubs in pastures across the Southeast. We evaluated a suite of newer pasture herbicides that included several combinations of 2,4-D, aminopyralid, fluroxypyr, metsulfuron, picloram, and triclopyr. Broadcast treatments were applied for 2 consecutive yr in August over the same individual rose clumps and mowing was done 6 mo after the second application. We found that none of the herbicides and rates tested effectively killed entire clumps but that Macartney rose was suppressed best with picloram 2,4-D treatments. Triclopyr was ineffective when applied alone or when tank-mixed with aminopyralid 2,4-D or aminopyralid metsulfuron. Metsulfuron was also ineffective and did not improve control when applied with aminopyralid alone or in combination with 2,4-D. These results indicate that typical annual broadcast applications currently utilized for broadleaf pasture weed control will not effectively eliminate the invasive shrub Macartney rose and more integrated methods need to be evaluated.

Perennial pepperweed is an invasive plant species in North America, native to temperate Eurasia and northern Africa. Effective biological control depends upon correct taxonomic identification. Therefore, we investigated morphological and genetic data (cpDNA sequences and amplified fragment length polymorphisms [AFLP]) in its native range, where the species is at times treated as multiple taxa (L. latifolium, L. affine and L. obtusum). We also analyzed genetic data to determine the number and distribution of haplotypes and genotypes in the invaded range. Using Bayesian analysis, we found three clusters of AFLP genotypes in the native range, but little correlation between these clusters and morphological characters used to distinguish taxa. Also, we found combinations of morphological character states within many native range plants that are incompatible with current species descriptions, offering no support for splitting L. latifolium sensu lato into three species. In North America 97% of the genetic variation was among populations and there were only eight AFLP genotypes in 288 plants, suggesting few introductions or a severe bottleneck, and little or no creation of new genotypes since introduction. We found plants in the native range that are genetically similar (88 to 99%) to six of the eight invasive AFLP genotypes, suggesting that Kazakhstan and China are origins for much of the North American invasion.

Nomenclature: Perennial pepperweed, Lepidium latifolium L. LEPLA, Lepidium affine Ledeb., Lepidium obtusum Basiner

Management Implications: Clear taxonomic identification of an invasive plant in its native and introduced ranges is a prerequisite for the success of any biological control project. Also, invasions can contain diverse assemblages of genotypes, which can affect herbivory. To verify the identity of perennial pepperweed populations from Eurasia that are being explored for biological control agent candidates we collected and analyzed morphological and genotypic data from populations in Eurasia and North America. In addition, we analyzed genotypic data to determine the diversity and distribution of perennial pepperweed genotypes in North America. Our results indicate that perennial pepperweed most probably consists of one taxon; not two or three as suggested in some recent floristic studies. We found that origins of common invasive genotypes are in Kazakhstan and China, suggesting that these regions should preferentially be searched in future foreign exploration for additional biological control agents. We found only eight invasive genotypes in North America, suggesting few introductions or a severe bottleneck, and little or no creation of new genotypes since introduction. The low diversity allowed us to provide seed representing all cpDNA sequence haplotypes for host-specificity studies, which should reduce the risk of any resistance to biological control agents being found after release.

The alien invasive vines black and pale swallowwort are currently spreading across eastern North America, invading parklands, old fields, restored forest sites, and other natural areas. These plants spread by wind-borne seed and can form dense stands where they become established. Although their current geographic ranges overlap, there is little known overlap locally. Preliminary observations and anecdotal information have associated black swallowwort with low-pH inceptisols and pale swallowwort with high-pH alfisols. We conducted a common garden field experiment repeated over two years and a growth chamber germination experiment to assess whether seedling emergence and performance of these two swallowworts are affected by soil type and/or soil pH. Soil pH was artificially modified. In the common garden experiment, plants of both species grown on the Onondaga County soil type (an alfisol) produced a smaller root mass than on the Orange County soil (an inceptisol). Also, in one of two years more seedlings emerged and plants produced more follicles on the Onondaga County soil. Soil pH did not affect seedling emergence, although plants grown on low pH soils had a smaller root dry mass compared with plants grown on higher pH soils. Soil pH effects on stem length, stem dry mass, and follicle production were inconsistent among years. Species differences were also evident, with more pale swallowwort seedlings emerging than black swallowwort seedlings, whereas black swallowwort plants mostly had greater biomass and fecundity than pale swallowwort plants. In the growth chamber experiment, final percentage seed germination was greater on the Onondaga County soil than on the Orange County soil. The germination speed index as well as the probability to reach 50% germination for black swallowwort was higher on the Onondaga County soil than the Orange County soil, but only at lower pH levels. The germination speed index of pale swallowwort on the Orange County soil was higher than black swallowwort at low, but not high, pH levels. In contrast, black swallowwort had a higher probability of reaching 50% germination than pale swallowwort on the Orange County soil at higher pH levels. Contrary to our expectations, interactions between the two swallowwort species with their associated soil type or with their presumably preferred soil pH were weak, contradictory, or non-existent in both experiments. This suggests that these two species can colonize and grow well in a relatively wide range of soil pH conditions. From a management perspective, our results suggest that the current range and local overlap of these two species will continue to increase and that early detection rapid response (EDRR) programs should be established in susceptible regions not yet colonized by these two invasive vines.

Nomenclature: Black (or Louise's) swallowwort, Vincetoxicum nigrum (L.) Moench, syn. Cynanchum louiseae Kartesz & Gandhi, Pale (or European) swallowwort, Vincetoxicum rossicum (Kleopow) Barbar., syn. Cynanchum rossicum (Kleopow) Borhidi

Management Implications: Black swallowwort (BSW) and pale swallowwort (PSW) have become an invasive weed problem in northeastern North America. Currently, there is little overlap at specific field sites of the two species. Anecdotal information has associated BSW with low-pH soils and PSW with high-pH soils. Using both a common garden field experiment and growth chamber study, we assessed whether seedling emergence and performance of these two swallowworts were affected by soil type and/or soil pH. We found that seedling emergence of BSW and PSW was generally not affected by varying levels of soil pH, although soil type could influence germination rates. Apart from root mass size, the effect of soil pH or soil type on subsequent growth, survival and reproduction of first-year plants was variable. There were more con

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.

Nomenclature: Miconia, Miconia calvescens DC. MICA20

Management Implications: Herbicide Ballistic Technology (HBT) is a novel application technique designed to deliver encapsulated herbicide projectiles with long-range accuracy and precision. We report on the performance of an HBT platform providing immediate control of miconia (Miconia calvescens DC.) satellite plants, detected while conducting helicopter surveillance calibrations in Hawaii's remote watersheds. Flight calibrations (n  =  13) generated efficiency parameters related to the functionality of the platform. Plant target density was a significant variable for determining search efficiency (min ha⁻¹), target acquisition rate (plants hr⁻¹) and herbicide use (g ae ha⁻¹). The product of detection efficacy and treatment efficacy estimated population mortality (i.e. reduction) as another operational parameter used in simulation models to project feasibility and expected cost of different population reduction strategies based on cost optimization and risk aversion. This research is critical to our technology transfer program that includes development of the standard operating procedure for safe use of the HBT platform, which has been approved by the Pacific Cooperative Studies Unit, University of Hawaii and approval by the Hawaii Department of Agriculture for a FIFRA Section 24c Special Local Needs registration for HBT-G4U200 with Garlon® 4 Ultra (EPA SLN Reg. No. HI-120001), with miconia listed as a target species.

Old World climbing fern (OWCF) is a highly invasive plant that is spreading rapidly and disrupting natural areas in Florida, with the potential to spread by wind-blown spores into Central and South America. Experiments were performed using gametophytes to determine the dose response of OWCF to metsulfuron methyl (metsulfuron). OWCF gametophytes were highly susceptible to metsulfuron with ≤ 1.4% survival at concentrations ≥ 27 mg ai L⁻¹. Metsulfuron OWCF gametophyte 50 and 95% inhibition (I₅₀ and I₉₅) values were 6.1 and 26.4 mg ai L⁻¹, respectively. Survival of treated gametophytes that developed into sporophytes was ≤ 0.014% at concentrations ≥ 27 mg ai L⁻¹, but no sporophytes developed at concentrations ≥ 432 mg ai L⁻¹. Metsulfuron OWCF sporophyte inhibition I₅₀ and I₉₅ values were 5.6 and 24.1 mg ai L⁻¹, respectively. At 216 mg ai L⁻¹ metsulfuron, half of the standard operational use rate, 1.1 × 10⁻⁸% of the treated gametophytes developed into sporophytes. The results indicate that the potential for tolerant, and potentially resistant, OWCF populations is higher using lower concentrations of metsulfuron as no gametophytes developed into sporophytes at the standard field treatment concentration of 432 mg ai L⁻¹.

Nomenclature: Metsulfuron methyl, Old World climbing fern, Lygodium microphyllum (Cav.) R. Br

Management Implications: Old World climbing fern (Lygodium microphyllum; OWCF) is currently invasive only in Florida outside it native range, but exhibits the potential to spread into areas of high diversity in Central and South America due to microscopic wind-blown spores. No previous research has examined the effects of metsulfuron on gametophytes of this species. OWCF gametophytes were highly susceptible to metsulfuron with ≤ 1.4% survival at concentrations ≥ 27 mg ai L⁻¹ and inhibition concentrations of 6.1 and 26.4 mg ai L⁻¹ for 50 and 95% inhibition rates (I₅₀ and I₉₅), respectively. OWCF sporophytes that developed from treated gametophytes had survival rates of ≤ 0.014% at concentrations ≥ 27 mg ai L⁻¹, with no sporophyte developing at concentrations ≥ 432 mg ai L⁻¹. I₅₀ and I₉₅ concentrations of metsulfuron for OWCF sporophytes that developed from treated gametophytes were 5.6 and 24.1 mg ai L⁻¹, respectively. Our results provide preliminary evidence that the potential for resistance in OWCF populations is higher using lower concentrations of metsulfuron, perhaps through selection for enhanced herbicide metabolism, as no gametophytes developed into sporophytes at the standard field treatment concentration of 432 mg ai L⁻¹.

Privet has escaped from cultivation and is invading natural areas throughout eastern North America. Understanding the pattern of invasion over time could help us develop more efficient management strategies. We studied the invasion history and spatial distribution pattern of privet by mapping age and spatial data for established patches in a 132-ha (326 ac) forested natural area in northeast Ohio. We determined the age of 331 geo-referenced patches by counting annual rings, and mapped them with corresponding land habitat. Age distribution and cumulative number of privet patches over about 40 yr showed three phases of invasion. The initial 19-yr lag phase was characterized as a dispersed spatial pattern (based on nearest neighbor analysis), with patches located mostly at edges of different habitats and open places. In a second phase of about 15 yr, an average of 19 patches were initiated yearly, in a pattern that trended towards clustered. The final phase began around 2007, as the rate of new patch establishment declined, possibly because of saturation of the suitable habitat. Establishment of new patches was not associated with specific habitats. Aggregation of patches with similar ages increased after 1998 and became significantly clustered. Mapping of clusters of old and young patches identified invasion hot spots and barriers. Results affirmed that the best time for invasive control is during the lag phase. By monitoring edge habitats associated with early establishment, managers might detect and control early invaders and delay the onset of the expansion phase.

Nomenclature: Privet, Ligustrum vulgare L

Management Implications: Invasive plants in natural areas are difficult to detect in early stages when control would be most effective. If managers knew where to expect initial establishment and the pattern of subsequent patch development, control strategies could be targeted more efficiently. In this study, we determined the age distribution and spatial pattern of patches of privet (Ligustrum vulgare), a woody invasive plant. We reconstructed the invasion history in a natural area in northeast Ohio where privet has escaped from home landscapes. Since the privet invasion is still in progress, understanding the history and pattern of the current invasion could provide insight into future spread. The oldest privet patch was dated to 1972, but significant increases in patch number did not begin until about 1991. Initial patches appeared mostly in edge habitats, but thereafter the distribution was more random and there was no clear invasion front related to topography or land use. Hot spot analysis suggested that the highly dispersed initial patches, which probably resulted from multiple random dispersals from one or more source populations, could have facilitated further invasion. The rate of new patch formation slowed around 2007, possibly because of saturation of suitable habitat. Results suggest that managers should monitor edge habitats to detect early privet invasion, and that a prolonged lag period provides time for early control efforts before rapid expansion occurs.

Desiccation following prolonged air exposure challenges survival of aquatic plants during droughts, water drawdowns, and overland dispersal. To improve predictions of plant response to air exposure, we observed the viability of vegetative fragments of 10 aquatic plant species (Cabomba caroliniana, Ceratophyllum demersum, Elodea canadensis, Egeria densa, Myriophyllum aquaticum, Myriophyllum heterophyllum, Myriophyllum spicatum, Potamogeton crispus, Potamogeton richardsonii, and Hydrilla verticillata) following desiccation. We recorded mass loss, desiccation rate, and plant fragment survival across a range of air exposures. Mass loss accurately predicted viability of aquatic plant fragments upon reintroduction to water. However, similar periods of air exposure differentially affected viability between species. Understanding viability following desiccation can contribute to predicting dispersal, improving eradication protocols, and disposing of aquatic plants following removal from invaded lakes or contaminated equipment.

Nomenclature: Brazilian egeria, Egeria densa Planch., common elodea, Elodea canadensis Michx., coontail, Ceratophyllum demersum L., curlyleaf pondweed, Potamogeton crispus L., Eurasian watermilfoil, Myriophyllum spicatum L., fanwort, Cabomba caroliniana Gray, hydrilla, Hydrilla verticillata (L. f.) Royle, parrotfeather, Myriophyllum aquaticum (Vell.) Verdc., Richardson's pondweed, Potamogeton richardsonii (A. Bennett) Rydb., variable-leaf watermilfoil, Myriophyllum heterophyllum Michx

Management Implications: A framework for assessing the vulnerability of ecosystems to invasion by aquatic weeds must consider many aspects of species invasions: which species will arrive, how will they get there, and will they establish and generate impacts following introduction. Knowledge about physiological responses to stressors provides critical input to such a framework. In our study, we compared the viability of vegetative fragments of 10 aquatic plant species following variable periods of desiccation. We found that while desiccation expectedly decreased plant viability, desiccation rates and tolerances differed significantly between plant species.

The species-specific nature of desiccation warrants species-specific management actions. Our results suggest that boat launch inspection programs should be extra vigilant in their search for species that are relatively desiccation-resistant or –tolerant, such as emergent Myriophyllum aquaticum. On the other hand, our finding that some common invasive plants (Ceratophyllum demersum, Hydrilla verticillata) are comparatively intolerant to air exposure suggests that for these species, greater attention should be given to specific situations that promote insulation of vegetative material (e.g., entrainment in nets or anchor wells, burial in sediments), plant propagules that are more tolerant or resistant to desiccation (e.g., seeds or tubers), and alternative invasion pathways (e.g., water garden contaminants).