Growth chamber studies were conducted using 55-L aquariums to evaluate the efficacy of the herbicide triclopyr and the fungal pathogen Mycoleptodiscus terrestris, applied alone and in combination against Eurasian watermilfoil. Treatments included 0.15, 0.40, and 1.50 mg acid equivalent (ae)/L triclopyr, 0.08, 0.16, and 0.32 ml/L M. terrestris, combinations of both agents at all rates, and an untreated control. Plants were exposed to all treatments for a 24-h contact time and plant biomass (shoot and roots) was recorded 6 wk after application. For both triclopyr and M. terrestris applied alone, plant control increased with treatment concentration. Compared with untreated plants, 1.50 mg/L triclopyr and 0.32 ml/L M. terrestris reduced Eurasian watermilfoil by 100 and 91%, respectively. Lower doses of herbicide or pathogen were less effective and plant recovery was observed from surviving plant tissues (stems and root crowns). Although M. terrestris at 0.08 ml/L did not significantly reduce shoot or root biomass and 0.15 mg/L triclopyr provided only 53% control of plants, combining both agents at these rates reduced Eurasian watermilfoil by 90%. Results demonstrated that integrating low doses of triclopyr with an indigenous pathogen, M. terrestris, can improve control of Eurasian watermilfoil. Lower use rates of triclopyr would minimize impacts to sensitive nontarget vegetation, reduce application costs, and may minimize impacts of label-imposed use restrictions.

Understanding the ecological distribution range of exotic trees in an arboreal ecosystem is essential to managing natural forest resources sustainably. Forest resource mapping can be applied as a powerful tool in the identification of forest resource threat patterns, and in monitoring ongoing changes associated with a landscape. This study offers an insight on Russian-olive and its impact on a spatially bound ecosystem, namely, Bismarck–Mandan Wildland–Urban Interface (BMWUI). Data from the National Agricultural Imagery Program collected in 2005 and 2010 and in situ reference data were used to estimate the potential habitat of Russian-olive using ArcGIS ArcInfo® 9.3 (ESRI, Redlands, CA). Russian-olive plants are discernible on aerial photographs with a fine spatial resolution because of silvery gray-green leaves in the upper strata of their canopies. Results showed that Russian-olive occupied 110 ha (272 acres) in BMWUI in 2005 and of that, 13 ha (12%) was in inundated habitats. In addition, Russian-olive in 2010 covered 125 ha within the BMWUI and of that, 25 ha (20%) was in inundated habitats. Russian-olive showed a close association with the silt loam and silty clay soil type, which occurs along the Missouri River floodplain. Our findings revealed that the species is well established in riparian habitats and other open habitats such as roadside and agricultural lands. There is a greater likelihood of lateral spread of Russian-olive throughout the BMWUI that may require active management to avert undesirable conservation impacts.

Previous research has shown that pyridine growth regulator herbicides can affect seed production in annual grasses including downy brome, Japanese brome, wheat, and other cereal grain crops. Aminocyclopyrachlor is a pyridine carboxylic acid growth regulator herbicide that has recently been registered for broadleaf weed and brush control in nonagricultural areas, which may help facilitate release of native perennial grasses in native plant restoration sites. The influence of aminocyclopyrachlor on downy brome seed production was evaluated at multiple application rates and timings under controlled field conditions. The effect of aminocyclopyrachlor on seed production was compared with aminopyralid, another pyridine growth regulator herbicide. When applied to downy brome plants in the early vegetative stage (EPOST) at approximately 580 growing degree days (GDD), aminocyclopyrachlor at 320 g ae ha−1 reduced seed germination by 50 to 88% in the first and second study years, respectively. Aminopyralid reduced seed germination by 94% in the first study year, but only 20% in the second year. When applied to downy brome plants in the early heading stage at approximately 1,235 GDD (LPOST), aminocyclopyrachlor at 320 g ae ha−1 reduced seed germination by 100% both years. Aminopyralid reduced seed germination by 95% in the first year, and 81% in the second year. Other than the observed reduction in seed germination, herbicides did not produce any visible changes in downy brome aboveground plant growth or development. Because downy brome seeds are relatively short-lived in soil, aminocyclopyrachlor and aminopyralid applications to downy brome–infested rangelands and other natural areas could result in reductions in downy brome population densities over time. No published data exist on the effect of aminocyclopyrachlor on seed production of desirable perennial grasses in natural ecosystems, thereby suggesting the need for further research.

Invasive smooth cordgrass (Spartina alterniflora Loisel) eradication is important for the health of many coastal ecosystems. An integrated regime of continuous submergence after clear mowing, with three interval levels between mowing and submergence (5, 10, and 15 d) and three submergence depths (20, 30, and 50 cm), was implemented in cofferdams enclosing invader populations along a Chinese coast. In July of the following year, after the roots of mowed S. alterniflora had been submerged for 12 mo, some ramets grew under the regime with an interval of 15 d and the regime with a submergence depth of 20 cm, but no ramets occurred under the regimes with submergence depths of 30 or 50 cm and intervals of 5 or 10 d. Four crab species were documented: Helice tridens tientsinensis Rathbun, Sesarma dehaani H. Milne-Edwards, Ocypode stimpsoni Ortmann, and Chiromantes haematocheir de Haan. Biomass and abundance values of crab species in the cofferdams were similar to those in the mudflats but different from those in smooth cordgrass populations. Thus, the treatment of submergence after mowing, which was implemented in the cofferdams, can control S. alterniflora and provide a mudflat-like habitat that promotes crab recovery if this treatment uses the proper combination of submergence depth and interval between mowing and submergence.

Aphthona spp. flea beetles were released in two ecological sites of the Little Missouri National Grasslands in southwestern North Dakota in 1999 to control leafy spurge. The change in leafy spurge density and soil seedbank composition was monitored to evaluate the effectiveness of the biological weed control agent and the associated change in plant communities 5, 10, and 15 yr after release in loamy overflow (valleys) and loamy sites (ridges). In 2014, 15 yr after release, leafy spurge stem density had decreased 94% from 110 to 7 stems m−2 in the loamy overflow sites and 88% from 78 to 9 stems m−2 in the loamy sites. Leafy spurge represented only 2% and 6% of the loamy overflow and loamy seedbanks in 2004, respectively, compared with nearly 67% and 70%, respectively, in 1999. There was a slow shift to reintroduction of native species into the seedbank over the last 15 yr. The number of desirable species increased to 21 by 2014 (more than three times the number of species in 1999) in the loamy overflow sites, and doubled to 14 species in the loamy sites, while less desirable forb species doubled in both sites. Desirable grass species doubled in the loamy overflow sites by 2014 but remained unchanged in loamy sites. Aphthona spp. successfully controlled leafy spurge for more than 15 yr without any additional control methods or costs to land managers and resulted in the slow return of a subset of native species.

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.

Exotic plants have the ability to modify soil seed banks in habitats they invade, but little is known about the legacy of invasion on seed banks once an exotic plant has successfully been controlled. Natural areas previously invaded by leafy spurge in the northern Great Plains typically have one of two fates following its removal: a return of native plants, or a secondary invasion of other exotic plants. It is unknown, however, if this difference in plant communities following leafy spurge control is due to seed bank differences. To answer this question, we monitored seed banks and standing vegetation for 2 yr in mixed-grass prairies that were previously invaded by leafy spurge but controlled within 5 yr of our study. We found that native plant seed banks were largely intact in areas previously invaded by leafy spurge, regardless of the current living plant community, and leafy spurge invasion history had a larger impact on cover and diversity of the vegetation than on the seed banks. Differences in plant communities following leafy spurge control do not appear to be related to the seed banks, and soil conditions may be more important in determining trajectories of these postinvasion communities.

Controlled burns and grazing are being tested to manage invasive grasses in the Prairie Pothole region of the Northern Great Plains. These practices, however, may inadvertently promote saltcedar infestations from seed by opening the vegetative canopy. Saltcedar seedling establishment was investigated in greenhouse experiments using intact soil cores from one summit and three footslope sites in eastern South Dakota. Establishment tests were conducted in soil cores collected from treatment and control plots immediately after spring fire treatment (postburn) and in cores that contained peak cool- or peak warm-season vegetation, with or without clipping (simulated grazing treatment), to simulate vegetation conditions typical of saltcedar seed-shed in northern regions. Cores were seeded with 100 saltcedar seeds and subirrigated to maintain high soil water conditions, characteristic of the environment near potholes during late spring/early summer. Seedlings were counted during the first 3 wk to estimate establishment and the height of five seedlings core−1 were measured weekly to estimate growth rates. Opening the canopy with fire or clipping increased saltcedar establishment. Cores taken immediately after fire treatment had two times more seedlings establish (38% vs. 19%) and greater average seedling growth rate (1.5 mm d−1 vs. 0.9 mm d−1) when compared with no-fire controls. Fire after seeding reduced seedling establishment to 5%, but did not affect growth rate. Saltcedar establishment in peak cool-season vegetation cores was 6% regardless of earlier fire treatment, whereas in peak warm-season vegetation, establishment ranged from 8% (no spring fire) to 17% (spring fire). If soils remain wet, invasion risk following spring fire may be greatest when warm-season grasses are flowering because this time coincides with northern saltcedar seed production. Areas adjacent to viable saltcedar seed sources should be managed to maximize canopy cover when seeds are released to limit further establishment. Fire after saltcedar seed deposition may control propagules and young seedlings.

Land managers must set weed management priorities if limited resources are to be utilized effectively. Weed surveys and inventories assist land managers in this process by providing information regarding the identity, location, and relative abundance of weeds on their land. Although this information is vital, it can be challenging to select a method that provides the necessary data to meet management objectives while remaining accurate and cost effective. This paper critically evaluates four wildland weed mapping methods. These methods were defined as (1) paper-drawn, (2) buffered-point, (3) screen-drawn, and (4) perimeter-walked. Polygons were drawn by hand on topographic maps in the paper-drawn method. The other methods utilized handheld geographic positioning system (GPS) technology to digitally record infestations. Six experienced weed mappers independently recorded the location and size of eight sagebrush patches using each method. Time and accuracy were evaluated for each method based upon mapping time, distance walked, horizontal precision error, estimated size error, and shape error. The paper-drawn method was significantly less accurate than GPS-based methods at recording patch size and location. There was no significant difference in the accuracy of the buffered-point, screen-drawn, and perimeter-walked methods at reporting patch size and location. The need to cover land area quickly and efficiently favors the selection of the buffered-point or screen-drawn method because of time and distance factors. However, if patch shape is an important factor, the perimeter-walked or buffered-point methods may be the best choices of methods tested.

Callery pear (Pyrus calleryana Decne.), a native of eastern Asia, has recently emerged as an important woody invader in much of the eastern United States. Little is known about its ecology in its new range. Its shade tolerance may be an important indicator of areas it is likely to invade. In this study, allometric equations were first developed to predict aboveground biomass components, including wood, branches, bark, leaves, and fruit, from diameter at stump height (dsh; 25 cm), by destructively harvesting 13 trees, ranging from 0.1 to 19.3 cm dsh. Then, a total of 23 wild-grown stands in the northern Kentucky/southwestern Ohio region were surveyed, with diameters of all woody stems sampled. Pyrus calleryana density, basal area, aboveground biomass, stand density index, size distribution inequality, and importance value were calculated for each site. Two-factor Weibull distributions were fit to diameter distributions. Allometric equations provided good fits for total aboveground biomass as well as individual components. Aboveground biomass levels fell below mean levels of native forest stands found in the United States. Stand density indices yielded values typical of shade-intolerant or midtolerant species. Stands with smaller trees generally had steeply declining monotonic diameter distributions, while stands with larger trees trended toward positively skewed monotonic distributions. These findings are consistent with a species that is either shade-intolerant or midtolerant. Thus, while this species is expected to invade open or disturbed areas, it is not expected to be an important invader under forest canopies. However, its extended deciduous habit is one shared by other understory woody invaders, and so this may allow it to survive under forest canopies.

The objective of this study was to use fecal near-infrared reflectance spectroscopy (NIRS) to estimate the percent spotted knapweed in the diet of grazing ewes to fine tune grazing prescriptions. In trial 1, five ewes were randomly selected from a band of 900 ewes to estimate weekly variation in percent spotted knapweed in the diet. Fecal samples from these ewes were collected weekly from June 22 through August 17 (nine collections per ewe for a total of 45 observations). In trial 2, fecal samples were collected from 89 ewes in the band to estimate variability in percent spotted knapweed in the diet among sheep at two sampling dates corresponding to the bud (July 13) and postflowering (August 15) stages of spotted knapweed phenology. In trial 1, the percent spotted knapweed in the diet was similar (P > 0.05) on June 22, June 29, July 13, and July 20 but was greater (P < 0.05) on July 6 than June 22 and 29. Percent spotted knapweed in the diet was also greater (P < 0.05) from July 27 through August 17 than from June 22 through July 20. On July 13 in trial 2, 55% of ewes had 0 to 5% spotted knapweed in their diets, whereas 44% of ewes had 5 to 20% spotted knapweed in their diets. On August 15, only 1% of ewes had < 10% spotted knapweed in their diets, whereas 44% of ewes had 20 to 25% spotted knapweed in their diets. The estimated percent spotted knapweed in the diet of the 89 ewes in trial 2 was similar to that of the five ewes during the same time period in sampling trial 1 (5.3% compared with 5.0% for sampling trials 1 and 2, respectively, on July 13 and 22.0% compared with 20.7% on August 15 and 17 for trials 1 and 2, respectively). This is the first study to estimate percent spotted knapweed in the diet of individual grazing ewes. These data suggest that the best time to graze spotted knapweed–infested pastures would be in late July or early August, when spotted knapweed is flowering, but before viable seed production.

We investigated the potential for an invasive sea lavender, Limonium ramosissimum subsp. provinciale (Algerian sea lavender; LIRA) to spread in San Francisco Estuary (SFE) tidal marshes by testing how two determinants of tidal marsh plant distribution, salinity and inundation, affect LIRA dispersal, germination, growth, and reproduction. Simulating dispersal in 0, 15, and 30 parts per thousand (ppt) salinity water, we found seeds remained afloat similarly regardless of salinity, and seed viability after floatation was high (88%); however, seeds in 0 ppt aquaria germinated after just 4 d, suggesting shorter dispersal distances in fresh than in brackish or saline water. Next, we compared LIRA and native halophyte seed germination in 0, 15, 30, and 45 ppt water. Percentage of germination was similar between species after 3 wk, but LIRA germinated faster in fresh water than all native species (90% vs. 5% germination after 4 d), suggesting a possible establishment advantage for LIRA at low salinities. Finally, we grew LIRA under crossed salinity and inundation levels in a tidal simulator for a growing season. LIRA growth and seed production increased when either salinity or inundation was reduced. We conclude that spread could be greatest among salt marshes due to high potential for seed dispersal in saline water, yet spread within marshes may be greatest in relatively lower salinity conditions where growth and reproduction are maximized.

Cutleaf teasel is an invasive, biennial plant that poses a significant threat to native species along roadsides in Missouri. Flowering plants, together with understory rosettes, often grow in dense patches. Detection of cutleaf teasel patches and accurate assessment of the infested area can enable targeted management along highways. Few studies have been conducted to identify specific species among a complex of vegetation composition along roadsides. In this study, hyperspectral images (63 bands in visible to near-infrared spectral region) with high spatial resolution (1 m) were analyzed to detect cutleaf teasel in two areas along a 6.44-km (4-mi) section of Interstate I-70 in mid Missouri. The identified classes included cutleaf teasel, bare soil, tree/shrub, grass/other broadleaf plants, and water. Classification of cutleaf teasel reached a user's accuracy of 82 to 84% and a producer's accuracy of 89% in the two sites. The conditional κ value was around 0.9 in both sites. The image-classified cutleaf teasel map provides a practical mechanism for identifying locations and extents of cutleaf teasel infestation so that specific cutleaf teasel management techniques can be implemented.

Cutleaf teasel is an exotic weed that infests roadside environments in Missouri. As a growing biennial, the plant develops as a rosette during the first year and bolts during the second. Dense patches contain flowering plants with understory rosettes. The objective of this work was to develop approaches for detecting cutleaf teasel patches with accurate assessment in a complex of species along a roadside. Thus, management of cutleaf teasel could be located at specific sites. Two hyperspectral images (63 bands with 1-m spatial resolution) were analyzed to detect cutleaf teasel along the Interstate Highway I-70 in mid Missouri. Classification of cutleaf teasel reached a user's accuracy of 82 to 84% and a producer's accuracy of 89% at the two sites. The image-classified teasel map provides a practical mechanism for identifying the locations and extents of cutleaf teasel infestation so that specific management techniques can be implemented.

Hybridization can play an important role in the evolution of invasiveness. Eurasian watermilfoil (Myriophyllum spicatum L.) is a widespread aquatic invasive plant species that hybridizes with native northern watermilfoil (Myriophyllum sibiricum Kom.). Previous studies have found mixed evidence for whether hybrid watermilfoil (Myriophyllum spicatum × sibiricum) and pure M. spicatum differ in vegetative growth rate and herbicide response. While several studies have emphasized variation in these traits among M. spicatum × sibiricum genotypes, variation within M. spicatum has not been considered. Therefore, it is unclear how much genetic variation influences invasive traits and management outcomes within M. spicatum versus between M. spicatum and M. spicatum × sibiricum. If M. spicatum × sibiricum genotypes are always more invasive than M. spicatum genotypes, simply distinguishing taxa may be sufficient for identifying lake management priorities; however, if significant phenotypic overlap is observed between taxa, distinguishing individual genotypes may be important for tailoring management strategies. We performed replicated trials of a vegetative growth and 2,4-D assay to measure clonal variation in growth rate and herbicide response of M. spicatum and M. spicatum × sibiricum. Our results indicate that M. spicatum × sibiricum exhibits higher average vegetative growth than M. spicatum, regardless of whether it was treated with subsurface applications of 2,4-D. We did not observe interactions between taxon and treatment or between genotype and treatment. Despite differences between M. spicatum and M. spicatum × sibiricum in average vegetative growth, there was substantial overlap between taxa. For example, we found that the fastest-growing genotype of pure M. spicatum did not differ significantly in average growth from the fastest-growing M. spicatum × sibiricum genotype. The potential for overlap between these invasive Myriophyllum taxa suggests that distinguishing and characterizing genotypes may be more informative for management than simply distinguishing between M. spicatum and M. spicatum × sibiricum.

Many naturalized populations of the invasive tree princess tree exist in North America, yet little research has quantified its effect on native plant communities. A series of recent wildfires in the Linville Gorge Wilderness Area (LGWA) promoted multiple large-scale princess tree invasions in this ecologically important area. To measure community shifts caused by these princess tree invasions across burn areas, we sampled vegetation in paired invaded and noninvaded plots in mature and immature invasions within two burn areas of the LGWA. Plant community composition shifted in response to princess tree invasion across all invasion stages and burn areas. Species richness and Shannon diversity values decreased in invaded plots. Overall community structure also differed in invaded plots within immature invasions (P=0.004). The distribution of princess tree age classes in both burn areas indicates that fire promotes invasion but is not necessary for subsequent recruitment. Additionally, preliminary genetic analyses among distinct princess tree populations revealed very low genetic diversity, suggesting that a single introduction may have occurred in the LGWA. This information regarding community shift and strong post-fire recruitment by princess tree may inform management decisions by prioritizing princess tree control immediately after wildfires and immediately before and after prescribed burns.

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.

Severe leaf blight of Japanese stiltgrass (JSG) from Bipolaris disease, causing significant decline in population density at some locations, has been reported sporadically in the field. Even so, much of the JSG in the mid-Atlantic is not diseased. Six populations of JSG from the field, one that was severely diseased by B. microstegii and the others “healthy,” were tested by artificial inoculation for susceptibility to both B. microstegii (five isolates) and B. drechsleri (three isolates). Populations of JSG in this study differed in their response to the two Bipolaris species, but within species of Bipolaris the plant responses were consistent. Plants from the diseased population of JSG from Frederick, MD, were very susceptible to B. microstegii, and plants from other populations from Maryland (three locations), Delaware, and Indiana were not. In contrast, B. drechsleri caused moderate disease on plants from all accessions but one, and it was significantly less aggressive than was B. microstegii on the susceptible accession of JSG. Results of a limited host range determination only with B. microstegii revealed hypersensitive responses, and therefore high levels of resistance, in corn (four cultivars) and sorghum (three accessions). The native, sympatric grass deertongue was not diseased in these tests. Results reveal a distinct differential response among populations of JSG to disease from B. microstegii, while in contrast, B. drechsleri is capable of causing disease on a broader range of JSG populations.

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.

Caucasian Old World bluestem (OWB) has escaped into native rangelands and could have unknown effects on distribution, utilization, growth, and reproduction of native plant and animal species. This trial was established to determine the rate and timing of glyphosate application that will provide the greatest OWB suppression. Treatments included glyphosate applied early at the five-leaf stage of growth with 1.12, 2.24, or 3.36 kg glyphosate ai ha−1 (1, 2, or 3 lb ai ac−1), sequential application with an early glyphosate application of 1.12, 2.24, or 3.36 kg ha−1 followed by a second application 8 wk later of either 1.12 or 2.24 kg ha−1, and a late-only application of 1.12, 2.24, or 3.36 kg ha−1. Sequential glyphosate applications with at least one of the early or late applications being 2.24 kg ha−1 or more reduced OWB frequencies from over 87% to below 30% each year. During a moist year, all sequential application treatments reduced OWB frequency to 12% or less. Frequency of OWB the year after application was directly related (r2 = 0.91) to the total amount of glyphosate applied during dry conditions. Seed heads were absent or nearly absent in all sequential application treatments, with the exception of glyphosate at 1.12 kg ha−1 applied early and late during the dry season. Sequential application of glyphosate that includes one treatment either early or late of 2.24 or 3.36 kg ha−1 appears to be the most effective treatment to reduce established OWB during dry years. During years of adequate moisture, a single late application of 2.24 or 3.36 kg ha−1 or sequential applications with 1.12 kg ha−1 at each application is as adequate as sequential applications with greater rates for reducing OWB frequency and achieving OWB control.

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.