Southwestern New Research Articles

Fish otolith geochemistry, environmental conditions and human occupation at Lake Mungo, Australia

Fish otoliths from the Willandra Lakes Region World Heritage Area (south-western New South Wales, Australia) have been analysed for oxygen isotopes and trace elements using in situ techniques, and dated by radiocarbon. The study focused on the lunettes of Lake Mungo, an overflow lake that only filled during flooding events and emptied by evaporation, and Lake Mulurulu, which was part of the running Willandra Creek system. Samples were collected from two different contexts: from hearths directly associated with human activity, and isolated surface finds. AMS radiocarbon dating constrains the human activity documented by five different hearths to a time span of less than 240 years around 19,350 cal. BP. These hearths were constructed in aeolian sediments with alternating clay and sand layers, indicative of fluctuating lake levels and occasional drying out. The geochemistry of the otoliths confirms this scenario, with shifts in Sr/Ca and Ba/Ca marking the entry of the fish into Lake Mungo several years before their death, and a subsequent increase in the δ18O by ∼4‰ indicating increasing evaporation of the lake. During sustained lake-full conditions there are considerably fewer traces of human presence. It seems that the evaporating Lake Mungo attracted people to harvest fish that might have become sluggish through oxygen starvation in an increasingly saline water body (easy prey hypothesis). In contrast, surface finds have a much wider range in radiocarbon age as a result of reworking, and do not necessarily indicate evaporative conditions, as shown by comparison with otoliths from upstream Lake Mulurulu.

Ritual Change and the Distant: Mesoamerican Iconography, Scarlet Macaws, and Great Kivas in the Mimbres Region of Southwestern New Mexico

AbstractThe Mimbres Classic period (A .D. 1000–1130) in southwestern New Mexico was marked by dramatic and complex changes. The use of Great Kivas ended, and macaws and Mesoamerican-inspired iconography appeared. We argue that these events were systematically related and signify observable changes in Mimbres ritual economy. The presence of macaws, images of macaws, and representations of characters and motifs from the Hero Twins saga suggest that ideology accompanied macaws north from the Gulf Coast of Mexico. We recognize and discuss episodes and icons from the saga painted on Mimbres black-on-white bowls and propose that the macaws and narrative reached the Mimbres region through direct acquisition rather than down-the-line trade. This research has significant implications for the importance of long distance travel to faraway places and interaction with distant peoples, Mesoamerican-southwestern United States relationships, changing religious practices in non-hierarchical societies, and the adoption of extrinsic elements into local settings.

Devonian Intrusion-Related Mineralization in Southwestern New Brunswick: Mount Pleasant Sn–W–Mo–Zn–In and Clarence Stream Au–Sb Deposits

Devonian Intrusion-Related Mineralization in Southwestern New Brunswick: Mount Pleasant Sn–W–Mo–Zn–In and Clarence Stream Au–Sb Deposits

Settlement patterns and the eastern boundary of the Northern Cities Shift – ERRATUM

This paper examines the dialectology of eastern New York State. Data are considered from twelve cities and villages bridging the gap between the Inland North dialect region (home to the Northern Cities Shift [NCS]) and the Western New England region. Communities are classified as belonging to the Inland North ‘‘core,’’ the Inland North ‘‘fringe,’’ or a non–Inland North region. The settlement history of these communities is used to explain the boundaries between the dialect regions; presence of the NCS is found to correlate well with heavy migration from southwestern New England early in a community’s history. Looking in detail at the different distributions of the individual sound changes involved in the NCS across the dialect regions established in this paper makes it possible to posit a reconstructed early history for the NCS and make hypotheses about the phonological character of the different sound changes.

Morphological Diagnosability ofAspidoscelis arizonae(Squamata: Teiidae) as an Indication of Evolutionary Divergence in theAspidoscelis inornataComplex

Lizards of the gonochoristic Aspidoscelis inornata (Little Striped Whiptail) complex are ubiquitous components of vertebrate faunas in diverse habitats in the southwestern United States and northern Mexico. One of these, Aspidoscelis arizonae ( = A. inornata arizonae, Arizona Striped Whiptail), is extant at only a few grassland areas in southeastern Arizona, but nonetheless played an important evolutionary role in the hybrid origins of seven obligatory parthenogenetic species. Although recognized as a distinct species by many, A. arizonae lacks a valid species description and only anecdotal data argue for its recognition. We were unable to separate it from geographically proximate A. inornata in southwestern New Mexico, using diagnostic morphological features (i.e., number of stripes, dark field coloration, sky blue ventral suffusion) previously used to delineate aspidoscelids. Furthermore, we evaluated additional diagnostic characters (i.e., body size plus ten meristic characters) in samples of A. arizon...

Re-Os geochronological constraints on the mineralizing events within the Mount Pleasant Caldera: implications for the timing of sub-volcanic magmatism

The Mount Pleasant granite-related polymetallic deposit, located on the southwestern margin of the Late Devonian to Early Carboniferous Mount Pleasant Caldera Complex in southwestern New Brunswick, contains a significant resource of tin, tungsten, molybdenum, zinc, indium, and bismuth. The Caldera Complex comprises Intracaldera, Exocaldera, and Late Caldera-Fill sequences and associated subvolcanic granitic rocks. Three granitic phases of the Mount Pleasant Granitic Suite (Granite I, II, and III) are recognized in the vicinity of the Mount Pleasant deposit and are interpreted to be fractionates of the more regionally exposed McDougall Brook Granitic Suite. Granite I and Granite II are associated with tungsten-molybdenum-bismuth, and tin-zinc-indium mineralization, respectively. Despite extensive research within the Caldera Complex, the exact age of mineralization at Mount Pleasant has never been firmly established. An inferred age of 363 ± 2 Ma was based on the proposed synchronicity of the U-Pb dated Bailey Rock Rhyolite of the Exocaldera Sequence with that of the undated McDougall Brook Granitic Suite, which intrudes the Intracaldera Sequence. Here, we present Re-Os dating of two molybdenite samples associated with the tungsten mineralization related to Granite I at the Fire Tower Zone, that constrain the initial onset of mineralization at Mount Pleasant to be between 369.7±1.6 Ma and 370.1±1.7 Ma. The new Re-Os ages clearly indicate that the McDougall Brook Granitic Suite, which pre-dates mineralization, must be at least seven million years older than the Bailey Rock Rhyolite, whose type-section is located within the Exocaldera Sequence. A re-examination of the gradational relationship between the McDougall Brook Granitic Suite and purported rocks of Bailey Rock Rhyolite within the Intracaldera Sequence revealed that the latter should instead be assigned to the Seelys Formation. Thus, deposition of the polymetallic mineralization likely took place contemporaneously with caldera collapse and an early phase of resurgent doming in response to degassing of the magma chamber rather than being coincident with erosion of the volcanic edifice as inferred from previous modeling of the eruptive history at Mount Pleasant.

Delimitation and management of emerald ash borer (Coleoptera: Buprestidae): case study at an outlier infestation in southwestern New York State, United States of America

AbstractWe present a case study in which we developed an adaptive delimitation technique and implemented and evaluated management of emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), in the first infestation discovered in New York State, United States of America. Delimitation was accomplished using 106 girdled “sentinel” trees and management included girdling 18 clusters of trees as population “sinks” to attract EAB and concentrate larvae for removal. Weekly monitoring of traps hung in sentinel trees facilitated early detection of EAB on 12 trees and allowed deployment of additional sentinels and sinks. Sentinel trees were felled and debarked; 12 were positive for EAB larvae and the spatial extent of infestation estimated at ∼48 km2. Sinks nearest the infestation core had the highest numbers of larvae. Larval densities were significantly greater in girdled trees than in proximate ungirdled trees suggesting removal of girdled trees prior to the following year's emergence would lower local EAB densities. Sinks deployed in response to an EAB on a sentinel tree purple prism trap more than 0.6 km from the centre of the known infestation were negative for EAB indicating these would not be effective for managing an infestation of similar size and in similar habitats. This case study provides valuable information to land managers to facilitate delimitation and management of newly discovered EAB infestations.

The anatomy of Last Glacial Maximum climate variations in south Westland, New Zealand, derived from pollen records

We present pollen records from three sites in south Westland, New Zealand, that document past vegetation and inferred climate change between approximately 30,000 and 15,000 cal. yr BP. Detailed radiocarbon dating of the enclosing sediments at one of those sites, Galway tarn, provides a more robust chronology for the structure and timing of climate-induced vegetation change than has previously been possible in this region. The Kawakawa/Oruanui tephra, a key isochronous marker, affords a precise stratigraphic link across all three pollen records, while other tie points are provided by key pollen-stratigraphic changes which appear to be synchronous across all three sites. Collectively, the records show three episodes in which grassland, interpreted as indicating mostly cold subalpine to alpine conditions, was prevalent in lowland south Westland, separated by phases dominated by subalpine shrubs and montane-lowland trees, indicating milder interstadial conditions. Dating, expressed as a Bayesian-estimated single ‘best’ age followed in parentheses by younger/older bounds of the 95% confidence modelled age range, indicates that a cold stadial episode, whose onset was marked by replacement of woodland by grassland, occurred between 28,730 (29,390–28,500) and 25,470 (26,090–25,270) cal. yr BP (years before AD, 1950), prior to the deposition of the Kawakawa/Oruanui tephra. Milder interstadial conditions prevailed between 25,470 (26,090–25,270) and 24,400 (24,840–24,120) cal. yr BP and between 22,630 (22,930–22,340) and 21,980 (22,210–21,580) cal. yr BP, separated by a return to cold stadial conditions between 24,400 and 22,630 cal. yr BP. A final episode of grass-dominated vegetation, indicating cold stadial conditions, occurred from 21,980 (22,210–21,580) to 18,490 (18,670–17,950) cal. yr BP. The decline in grass pollen, indicating progressive climate amelioration, was well advanced by 17,370 (17,730–17,110) cal. yr BP, indicating that the onset of the termination in south Westland occurred sometime between ca 18,490 and ca 17,370 cal. yr BP. A similar general pattern of stadials and interstadials is seen, to varying degrees of resolution but generally with lesser chronological control, in many other paleoclimate proxy records from the New Zealand region. This highly resolved chronology of vegetation changes from southwestern New Zealand contributes to the examination of past climate variations in the southwest Pacific region. The stadial and interstadial episodes defined by south Westland pollen records represent notable climate variability during the latter part of the Last Glaciation. Similar climatic patterns recorded farther afield, for example from Antarctica and the Southern Ocean, imply that climate variations during the latter part of the Last Glaciation and the transition to the Holocene interglacial were inter-regionally extensive in the Southern Hemisphere and thus important to understand in detail and to place into a global context.

Variables affecting sediment sulfide concentrations in regulatory monitoring at salmon farms in the Bay of Fundy, Canada

Annual monitoring of sediments is conducted under salmon farms in the southwestern New Brunswick (SWNB) area of the Bay of Fundy, Canada, from August to October. We examined the relationships between the average sediment sulfide concentrations at salmon farms monitored from 2006 to 2009 and some variables related to farm operations: farm age, predicted average near-surface current speed, and estimated biomass of salmon at the time of monitoring. Data for all of these variables were available for 87% of salmon farms monitored in these years (farms that had been inactive for >1 yr were excluded). The year of monitoring had no significant effect, so data from all 4 yr were combined. The ability of the 3 variables to predict sulfide concentrations at the time of monitoring was analyzed using a linear model with log-transformation of variables (except farm age). Each variable individually showed a significant correlation with sulfide concentration, but the model including all 3 variables explained only 37% of the variation. Current speed and biomass explained the highest proportions of sulfide variation (together 35%). Almost 30% of monitoring events occurred at farms holding no fish. When these fallowed sites were excluded, the model explained only 24% of sulfide variation, with current speed being the most important predictor variable. Management actions targeted at farm size (biomass) and physical aspects of sites (especially current speed) may help to reduce the risk of causing adverse benthic impacts, but measurable effects may not be observed due to the large amount of sulfide variation that is not explained by these variables.

Settlement patterns and the eastern boundary of the Northern Cities Shift

This paper examines the dialectology of eastern New York State. Data are considered from twelve cities and villages bridging the gap between the Inland North dialect region (home to the Northern Cities Shift [NCS]) and the Western New England region. Communities are classified as belonging to the Inland North “core,” the Inland North “fringe,” or a non–Inland North region. The settlement history of these communities is used to explain the boundaries between the dialect regions; presence of the NCS is found to correlate well with heavy migration from southwestern New England early in a community's history. Looking in detail at the different distributions of the individual sound changes involved in the NCS across the dialect regions established in this paper makes it possible to posit a reconstructed early history for the NCS and make hypotheses about the phonological character of the different sound changes.

Late Cretaceous U–Pb tuff ages from the Skunk Ranch Formation and their implications for age of Laramide deformation, Little Hatchet Mountains, southwestern New Mexico, U.S.A.

LA-ICPMS U–Pb ages of individual zircon crystals from reworked ash-fall tuff beds in lacustrine strata of the Skunk Ranch Formation, a synorogenic unit deposited in a Laramide intermontane basin in the Little Hatchet Mountains, southwestern New Mexico, indicate an early Maastrichtian depositional age of 71–70 Ma. The dated beds are equivalent to nearby growth strata that are partially cut by, and folded over, a Laramide reverse fault. The strata thus record final displacement on the reverse fault and indicate an early Maastrichtian age for fault offset. The Skunk Ranch Formation was previously interpreted as Eocene in age and inferred to record the second event in a two-stage Laramide deformational history in the mountain range. In addition to significantly condensing the age range of the Laramide section and clarifying stratigraphic correlation in the Little Hatchet Mountains, the new ages of the formation also indicate that Laramide deformation in the range was likely restricted to a single Late Cretaceous episode.

Effect of image spatial and spectral characteristics on mapping semi-arid rangeland vegetation using multiple endmember spectral mixture analysis (MESMA)

Encroachment of invasive shrubs into grassland areas on rangelands in the southwestern United States threatens the viability of livestock production and can severely alter hydrology and biodiversity. Novel remote sensing technologies may provide useful information for monitoring and remediating this threat. The objectives were to investigate multiple endmember spectral mixture analysis (MESMA) as an approach to map rangeland vegetation using hyperspectral remote sensing imagery and to test the sensitivity of MESMA to alternative image spatial resolutions and spectral waveband combinations. Data from two Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) overflights at the Jornada Experimental Range in southwestern New Mexico were used in the analysis. Endmember spectra were selected from a library of ground-based spectral observations collected with a field spectroradiometer. A 4-endmember MESMA was conducted for both AVIRIS images at their native spatial resolutions using 113 10-nm wavebands from 422 to 2339nm. Additional MESMAs were conducted at 10 multiples of the images' native spatial resolution and for 6 alternative combinations of spectral waveband subregions. Maps of endmember fractional cover for green shrub vegetation, nonphotosynthetic grass vegetation, and bare soil were comparable to an earlier vegetation classification map of Jornada. MESMA fractional cover estimates for the green vegetation endmember were positively correlated with the normalized difference vegetation index (NDVI) with correlation coefficients (r) greater than 0.58. Correlation coefficients between the sum of the green and nonphotosynthetic vegetation endmembers and the cellulose absorption index (CAI) were greater than 0.59. Correlation coefficients between MESMA fractional green vegetation cover and NDVI from independent multispectral images were greater than 0.57. Despite losses in spatial detail at coarser image spatial resolutions, MESMA results for images with spatial resolution degraded by a factor of 10 (~150m) were similar to aggregated results for MESMA at the native spatial resolution (~15m). Additionally, MESMA results were shown to be substantially more sensitive to the spectral wavebands used in the analysis as compared to the spatial resolution of the images. Considered together, the MESMA results at Jornada indicated that fine spectral resolution with hyperspectral remote sensing was substantially more important than incremental changes in image spatial scale from 15m to 150m.

Addendum to “Clearing, grazing and reservation: assessing regional impacts of vegetation management on the fauna of south western New South Wales”: the species assemblages

Ellis et al. (2007) classified the fauna of south western New South Wales into a management related structure of specialised and generalist species assemblages. The broad description of this system was presented in the paper but the detailed assignment of species to the various groups and the relationships between the groups was not published when supplementary material was not produced with the book. To prevent the loss of this information, which is important for applying the results of this study to other situations, the assignment of species to broad management groups and assemblages is now published as Table 1 (below). The relationship between specialist assemblages, which would be actively conserved through appropriate vegetation and/or water management, and their relation to vegetation types was presented in the original publication. The relationship between vegetation types and generalist assemblages, which would accrue benefits from actions for specialist assemblages in the same vegetation type, is given in Table 2 (below). Habitat mapping through broad vegetation types was thought not to adequately reflect the requirements of shorebirds and no analysis of their distribution was attempted.

Referrals to a Regional Rehabilitation Clinic in South Western New South Wales, Australia

An outreach fly-in fly-out rehabilitation medicine service has been established at a regional centre in south western, New South Wales, Australia to support local practitioners. This service includes an outpatient clinic, and an inpatients case conference and consultations. This study examined new referrals to the regional rehabilitation clinic over a 12 month period. There were 94 new patients with the median age of 57.5 years. The main reason for referral was noncancer pain assessment and management (60 patients, 63.8%); followed by post hospital discharge follow up (26 patients, 27.7%). The majority of patients with pain were already on opioid therapy at the time of initial consultation. 18 patients were found to be on a high dose of opioids (>100 mg/day of oral morphine or equivalent) with no recent pain specialist input. Risks of opioid related problems were assessed and identified in those patients with a high dose of opioid therapy. Reasons and barriers influencing opioid therapy for non-cancer chronic pain in the regional area are discussed. Further study is required to establish specialist rehabilitation medicine needs from local general practitioners perspective in regional areas.

Mid-Late Quaternary vegetation and climate change reconstructed from palynology of marine cores off southwestern New Zealand

Little is known about how mid-latitude Southern Hemisphere terrestrial vegetation responded during glacial terminations and the warmer phases of the Late Quaternary, especially beyond the last glacial cycle where records are commonly fragmentary and poorly-dated. The timing, magnitude and sequence of environmental changes are investigated here for terminations (T) I, II and V and their subsequent warm interglacials of MIS 1, 5e and 11 by direct correlation of terrestrial palynomorphs (pollen and spores) and marine climate indicators in marine piston cores MD06-2990/2991 recovered from the East Tasman Sea, west of South Island, New Zealand. The climate there is strongly influenced by the prevailing mid-latitude westerly wind belt that generates significant amounts of orographic rainfall and the proximity of the ocean which moderates temperature variability. Chronological constraint for the cores is provided by δ¹⁸O stratigraphy, radiocarbon chronology and the identification of two widespread silicic tephra horizons (25.6 ka Kawakawa/Oruanui Tephra (KOT); ~345 ka Rangitawa Tephra (RtT)) sourced from the central North Island. Similar vegetation changes over the last two glacial cycles at MD06-2991 and in the adjacent nearby on land record of vegetation-climate change from Okarito Bog permit transfer of the well resolved Marine Isotope Stage (MIS) chronology to Okarito for the pre radiocarbon dated interval (~139-28 ka). Placing both sequences on a common age scale nonetheless assumes there is minimal lag between pollen production and final deposition on the seafloor. However, the timing of Late Pleistocene palynomorph events and KOT between independently dated marine and terrestrial sedimentary sequences are found in this study to be indistinguishable, which supports the direct transfer of terrestrially derived ages to the marine realm and vice versa. Vegetation change in southwestern New Zealand is of similar structure during T-I and T-II, despite different amplitudes of forcing (i.e., insolation rise, CO₂ concentrations). In a climate amelioration scenario, shrubland-grassland gave rise to dominantly podocarp-broadleaf forest taxa, with accompanying rises in mean annual air temperature (MAAT) estimated from Okarito pollen typically synchronous with nearby ocean temperatures. The T-II amelioration commenced after ~139 ka in response to increasing boreal summer insolation intensity, with prominent ocean-atmosphere warming over the period from ~133-130 ka. In contrast, northern mid-high latitude paleoclimate records display cooling over Heinrich Stadial 11 (~135-130 ka), and are prominently warm from ~130-128 ka, while southwestern New Zealand and the adjacent ocean displays cooling. Such millennial-scale climate asynchrony between the hemispheres is most likely a result of a systematic, but non-linear re-organisation of the ocean-atmosphere circulation system in response to orbital forcing. The subsequent MIS 5e climatic optimum in Westland was between ~128-123 ka, with maximum temperatures reconstructed in the ocean…

Quantifying Hg within ectomycorrhizal fruiting bodies, from emergence to senescence

Ectomycorrhizal fruiting bodies (basidiomata) collected from forested areas in southwestern New Brunswick were analyzed for total mercury, sulphur, nitrogen, and carbon concentrations (THg, TS, TN, and TC, respectively). This analysis was done for caps and stalks and by development stage (emergent, mature, senescent) across 27 species associated with five classes, eight families, and 13 genera. Across the species, THg correlated positively with TN and TS, thereby implying N as well as S mitigated transfer of Hg from the mycelia into the basidiomata, with THg ranging from 3 to 10 457 ppb. TS, TN, and TC varied from 0.07 to 1, 1 to 11, and 43 to 53 %, respectively. Cap and stalk THg, TS, TN, and TC were also correlated to one another, with mean stalk/cap ratios of 0.59, 0.76, 0.71, and 0.98, respectively. Soil availability indexed by THg, TS, TN, and TC within the forest floor contributed to basidiomatal THg as well. THg, THg/TS, and THg/N varied strongly by species. These variations involved: (i) no growth dilution and no volatilization (Group I), (ii) growth dilution only (Group II), (iii) growth dilution followed by loss during senescence (Group III), and (iv) growth dilution combined with loss from emergence onward (Group IV). Depending on species, TN and TS remained the same or declined from 100 % at emergence to about 80 and 70 % at senescence. Lack of THg decline for the Group I species would be due to HgS encapsulation. Reanalyzing the freeze-dried samples revealed that THg continued to drop during the first year of air-dry storage for the Group II, II, and IV species, but TS, TN, and TC remained stable. The results were quantified by way of best-fitted regression models.

Early diagenetic processes in relation to river discharge and coastal upwelling in the Aru Sea, Indonesia

The Aru Sea receives massive sediment discharge (427×106tyr−1) from ≈30 rivers in southwestern New Guinea and upwelling of nutrient-rich water from the Banda Sea. This region is a rich fishing ground with total catch exceeding 220,000tyr−1, mostly in areas enriched by coastal upwelling. Reduction of Fe (range: 0–89.6mmol Fem−2day−1) and Mn (range: 2.2–32.6mmol Mnm−2day−1) dominates Corg decomposition in homogenous silt and clay deposits and aerobic metabolism dominates in sandy deposits or sediments showing evidence of extensive physical disturbance, or both. Discrepancies between fluxes within sediments and across the sediment–water interface, diagenetic modeling, and mineral saturation states show significant loss of dissolved inorganic carbon (DIC) and highly supersaturated conditions, implying precipitation of authigenic carbonate minerals. Sedimentary δ13C values show that most total organic carbon (TOC) is marine-derived in the upwelling area, with a decline in terrestrially-derived material from inshore to the outer shelf. Rates of O2 uptake and DIC release across the sediment–water interface and depth-integrated, production rates of DIC and NH4+ are highest where upwelling enriches phytoplankton and fisheries production. Sedimentary organic matter is reactive as evidenced by rapid decomposition rates, and porewater and solid-phase stoichiometry. Massive discharge of highly weathered debris, physical disturbance, rapid deposition of vascular plant detritus inshore, and extensive trawling foster oxic and suboxic diagenesis under nonsteady-state conditions. Rates of C and N remineralization were equivalent to rates measured on other tropical shelves, supporting the notion that tropical margins are efficient ‘incinerators’ of organic matter, even in the Aru Sea where cycling of organic matter as a result of upwelling is decoupled from that resulting from riverine inputs.

Occurrence of Sprouts and Seedlings of Pinyon Pines, Alligator Junipers, and Gray Oaks Following Harvest of Fuelwood and Prescribed Burning

Abstract Objectives were to determine number and height of sprouts and seedlings following clearcutting of a mesa dominated by pinyon pines (Pinus edulis) and alligator junipers (Juniperus deppeana) in southwestern New Mexico and to determine effects of prescribed burning for control of sprouts and seedlings. No stump of pinyon pine sprouted. Nearly 50% of stumps of alligator junipers sprouted with most occurring in plots with slash removed; the fewest and tallest sprouts occurred in plots with slash uniformly scattered following clearcutting. Nearly 25% of stumps of gray oaks (Quercus grisea) sprouted. Burning in the same year as clearcutting did not affect sprouting of gray oaks as much as other treatments. Not burning clearcuts and leaving slash scattered resulted in the fewest sprouts, and shortest sprouts of gray oaks occurred in plots with slash removed. Seedlings of pinyon pines, alligator junipers, and gray oaks were most prevalent in uncut control plots. Some seedlings of alligator junipers were ...

331 A bristlecone pine forest from the early Oligocene of southwestern New Mexico, USA : Evidence for vegetation response to the Eocene-Oligocene transition in interior North America

331 A bristlecone pine forest from the early Oligocene of southwestern New Mexico, USA : Evidence for vegetation response to the Eocene-Oligocene transition in interior North America

First Report of Bacterial Wilt Caused by Erwinia tracheiphila on Pumpkin and Watermelon in New Mexico.

Pumpkin (Cucurbita pepo L., cv. Magic Lantern) and watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai, cvs. Millionaire and Sangrea) plants with wilting leaves and collapse of entire vines were observed during the 2005 and 2006 growing seasons in several fields in southwestern New Mexico (Luna and Hidalgo counties) with an incidence ranging from 7 to 25% and less than 1% in pumpkin and watermelon fields, respectively. Sticky, hyaline strands were visible when vines were cut transversally, indicative of bacterial wilt caused by Erwinia tracheiphila (2). In the pumpkin fields, 12-spotted cucumber beetles, vector insects of E. tracheiphila, were found on plants at the first-true-leaf stage, which were treated with dimethoate. At the 4- to 5-leaf stage, 5 to 10% of the plants were wilted and were removed by hand. Less than 1% of the plants showed symptoms prior to bloom, when a high population of beetles was observed, and the fields were treated with thiamethoxam. To isolate the causal agent of the wilt symptoms, six, 1-cm vine segments and three to five beetles were surface sterilized in 1% NaOCl for 2 min, rinsed and macerated in sterile distilled water, and plated onto potato dextrose agar, nutrient agar, and King's medium B. After incubation at 25°C, bacterial colonies emerged on all media and were grayish white-to-cream, circular, smooth, and glittering. Isolated bacteria were gram negative, did not grow at 39°C, produced hydrogen sulfide gas from hydrolysis of cysteine, and did not hydrolyze litmus milk and starch. With Ready-To-Go PCR beads and 16S rDNA-based primers ET1/ET2 (1), a 700-bp product was obtained from each of two isolates, consistent with previously reported data for E. tracheiphila (1,3). For the pathogenicity tests, 10 seedlings of pumpkin cv. Magic Lantern and watermelon cv. Millionaire were inoculated with each isolate in the greenhouse at the second fully expanded leaf stage using two methods. In the first method, stems were injected with bacterial suspension (106 CFU/ml) using a hypodermic needle. In the second method, a dab of bacterial colonies was taken with a sterile toothpick to stab the cotyledonary axils. Control seedlings were stem injected with distilled water or stabbed with a sterile toothpick. The experiments were conducted four times. Inoculated plants were placed in a humid chamber at 23 to 25°C. Plant wilting was observed within 4 days when stab inoculated with toothpicks and within 7 to 10 days when stem injected with bacterial suspension. Bacterial colonies recovered from inoculated plants were identical to those recovered from field infected plants. To our knowledge, this is the first report of bacterial wilt on pumpkin and watermelon in New Mexico.