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In California, soilborne Phytophthora species have been increasingly reported from diseased plants in nurseries and in failing restoration sites. To determine the role these pathogens may play in failing restorations and to better limit their introduction, the pathogenicity of Phytophthora species newly isolated from plant species used in restorations needs to be demonstrated. However, there is no consensus on the best and most cost-effective approach to confirm pathogenicity of Phytophthora species on putative hosts. The first objective of this study was to compare the efficacy of stem vs. root inoculations to test the pathogenicity of soilborne Phytophthoras, and to do so, we compared mortality and disease symptoms of Diplacus aurantiacus plants inoculated with Phytophthora megasperma and P. crassamura through root and stem techniques. The second objective was to assess the pathogenicity of P. crassamura and P. megasperma on D. aurantiacus, of Phytophthora multivora and P. megasperma on Frangula californica and of P. multivora on Ceanothus thyrsiflorus. Root inoculations resulted in higher pathogen re-isolation and in greater leaf necrosis and mortality for all pathogen and host combinations. Considering both root and stem inoculations, Koch's postulates were completed for all pathogen and host combinations, except for Frangula californica inoculated with P. megasperma. [ABSTRACT FROM AUTHOR]

In human-modified landscapes, understanding how habitat characteristics influence the diversity and composition of beneficial organisms is critical to conservation efforts and modeling ecosystem services. Assessing turnover, or the magnitude of change in species composition across sites or through time, is crucial to said efforts, yet is often overlooked. For pollinators such as wild bees, variables influencing temporal turnover, particularly across seasons within a year, remain poorly understood. To investigate how local and landscape characteristics correlate with bee diversity and turnover across seasons, we recorded wild bee and flowering ornamental plant assemblages at 13 plant nurseries in California between spring and autumn over 2 years. Nurseries cultivate a broad diversity of flowering plant species that differ widely across sites and seasons, providing an opportunity to test for correlations between turnover and diversity of plants and bees. As expected, we documented strong seasonal trends in wild bee diversity and composition. We found that local habitat factors, such as increased cultivation of native plants, were positively associated with bee diversity in sweep netting collections, whereas we detected moderate influences of landscape level factors such as proportion of surrounding natural area in passive trap collections. We also detected a moderate positive correlation between the magnitude of turnover in plant species and that of bee species (as number of taxa gained) across consecutive seasons. Our results have implications for the conservation of wild bees in ornamental plant landscapes, and highlight the utility of plant nurseries for investigating hypotheses related to diversity and turnover in plant–pollinator systems. [ABSTRACT FROM AUTHOR]

1. An ongoing challenge in ecology is predicting how characteristics of communities correspond to habitat features. Examining variation in functional traits across species may reveal patterns not discernible from measures of mere abundance or richness. For beneficial insects like wild bees, functional trait‐based approaches are often used to characterise communities in different agricultural habitats. 2. However, no such approach has yet been applied in horticultural plant nurseries, which represent intensively managed artificial flowering plant assemblages. Certain nurseries mostly cultivate regionally native flowering plants, allowing one to test how differences between local plant assemblages may correlate with bee functional traits. 3. We surveyed bee assemblages at native and conventional plant nurseries in southern California from spring through autumn over 2 years, while also documenting the native status of blooming plants in sampling plots. Bees were classified into different functional categories based on their diet breadth, nesting location, and social organisation. 4. At native plant nurseries, we netted proportionally more specialist bee species and fewer generalist species than at conventional nurseries. Nesting location and social organisation of bee samples did not differ between nursery types. Meanwhile, landscape‐level features were not associated with any observed functional trait metrics of bee collections. Furthermore, network‐level specialisation of bee‐plant interactions was higher at conventional nurseries. 5. Our results suggest that a horticultural cultivation practice is quantifiably correlated with the functional distribution of resident bee assemblages. These results are important and encouraging to pollinator conservation efforts in nursery systems and other human‐modified landscapes dominated by ornamental plants. [ABSTRACT FROM AUTHOR]

Ecological restoration has become increasingly important in conservation. Yet, synthesized statistics are scarce with respect to essential characteristics of restoration activities. We surveyed restoration stakeholders in the U.S. states of Arizona and California to evaluate key attributes in restoration activities including ecosystems of focus, goals, size, cost, duration, and the prevalence of recommended restoration practices. We also examined how some of the attributes varied with size of restoration, ecosystem type, and state identity. While enhancing biodiversity and increasing plant cover were common goals in the two states, restoration in California also focused more on wildlife habitat re‐establishment and weed control. Restoration in Arizona was implemented more in arid/semiarid systems, larger in size, shorter in duration, used more passive restoration, spent more on equipment, and was less likely to source plants from native plant nurseries. Labor was the most expensive restoration component regardless of state identity and ecosystem type. Per unit area cost of restoration decreased with increasing size of restoration. Yet, the decline in this cost was more strongly explained by moving from mesic to arid/semiarid ecosystems. Duration of restoration projects increased with size of restoration and in more mesic ecosystems. Overall, restoration in mesic ecosystems, compared to arid/semiarid systems, was smaller in size, higher in cost, and longer in duration. These results confirmed that ecological and socio‐political conditions impact restoration goals and practice, with implications of how research can further support practitioners to achieve restoration success under practical constraints revealed by these results. [ABSTRACT FROM AUTHOR]

Mark-recapture experiments reveal foraging behavior and plant fidelity of native bees in plant nurseries Keywords: agroecosystems; California; foraging fidelity; Halictus; native plants; ornamental plants EN agroecosystems California foraging fidelity Halictus native plants ornamental plants 1 4 4 06/04/20 20200601 NES 200601 Understanding the spatial and temporal foraging patterns of pollinators is essential to conserving these organisms in human-modified landscapes, such as agroecosystems (Cranmer et al. [3]). These bees not only foraged in the same general location the next day, but of the 106 recaptured bees, 102 (96.2%) foraged on the same plant species as the previous day despite the broad diversity of plants flowering in nurseries. Although more bees were recaptured on native plants overall, some bees still displayed relatively high rates of fidelity to nonnative plants, though we found no preference for or against any nonnative plant species. [Extracted from the article]

Juvenile white sharks distribute in coastal nursery areas, which are essential for population growth. Bahía Sebastián Vizcaíno (BSV), Mexico, is a white shark nursery area in the north‐eastern Pacific. Despite existing regulations forbidding the capture of white sharks, incidental catches still occur in some areas.Artisanal fisheries constitute one of the most important economic activities in BSV, yet no formal description of either these fisheries or the incidental catch of juvenile white sharks exists due to the poor data reporting system, thus preventing a clear understanding of the implications of these catches for the white shark population of the north‐eastern Pacific.Artisanal fishing activities and their interactions with juvenile white sharks in BSV are described based on fishermen's knowledge. Artisanal fisheries in BSV are multi‐specific, targeting mostly bottom‐related species (e.g. white seabass and California halibut) that are also common prey for juvenile white sharks. These activities are the only source of income for the majority of fishermen in BSV and are conducted throughout the year, with gillnets being the main fishing gear.White sharks are incidentally caught in bottom gillnets mainly during the summer, although another peak in incidental catch was recorded during winter, possibly related to the presence of juvenile white sharks from California, USA. The most common size of juvenile white sharks incidentally caught was <2 m in the nearshore areas close to the mouth of the Ojo de Liebre Lagoon; larger juveniles (~3 m) were caught in areas near Cedros, Natividad, and San Benito Islands.The multi‐specific nature of BSV artisanal fisheries and their socio‐economic value, and the high post‐release survival of juvenile white sharks suggest that future regulatory actions should focus on the release of incidentally caught live juvenile white sharks and the involvement of the BSV fishing community to increase the effectiveness of management efforts. [ABSTRACT FROM AUTHOR]

Close residential proximity to powerlines and high magnetic fields exposure may be associated with elevated childhood leukemia risks as reported by prior studies and pooled analyses. Magnetic fields exposure from high-voltage powerlines is associated with proximity to these powerlines and consequently with any factor varying with distance. Areas underneath powerlines in California may be sites for commercial plant nurseries that can use pesticides, a potential childhood leukemia risk factor. Assess if potential pesticide exposure from commercial plant nurseries is a confounder or interacts with proximity or magnetic fields exposure from high-voltage powerlines to increase childhood leukemia risk. A comprehensive childhood leukemia record-based case-control study with 5788 cases and 5788 controls (born and diagnosed in California, 1986–2008) was conducted. Pesticide, powerline, and magnetic field exposure assessment utilized models that incorporated geographical information systems, aerial satellite images, site visits and other historical information. The relationship for calculated fields with childhood leukemia (odds ratio (OR) 1.51, 95% confidence interval (CI) 0.70–3.23) slightly attenuated when controlling for nursery proximity (OR 1.43, 95% CI 0.65–3.16) or restricting analysis to subjects living far (>300 m) from nurseries (OR 1.43, 95% CI 0.79–2.60). A similar association pattern was observed between distance to high-voltage powerlines and childhood leukemia. The association between nursery proximity and childhood leukemia was unchanged or only slightly attenuated when controlling for calculated fields or powerline distance; ORs remained above 2 when excluding subjects with high calculated fields or close powerline proximity (OR 2.16, 95% CI 0.82–5.67 and OR 2.15, 95% CI 0.82–5.64, respectively). The observed relationships were robust to different time periods, reference categories, and cut points. Close residential proximity to nurseries is suggested as an independent childhood leukemia risk factor. Our results do not support plant nurseries as an explanation for observed childhood leukemia risks for powerline proximity and magnetic fields exposure, although small numbers of subjects concurrently exposed to high magnetic fields, close powerline proximity and plant nurseries limited our ability to fully assess potential confounding. •Close proximity to plant nurseries is a potential childhood leukemia risk factor. • Proximity to nurseries did not explain distance to power lines and CL associations. • Proximity to nurseries did not explain magnetic field and CL associations. • First detailed study of pesticides as a confounder for magnetic fields and CL. [ABSTRACT FROM AUTHOR]

In the late 1990s, widespread outbreaks of Pierce's disease in grapevines were linked to transmission via the glassy-winged sharpshooter (GWSS), threatening California's multibillion-dollar table, raisin and wine grape industries. Government agencies responded to the crisis by implementing two control programs to manage GWSS. We analyzed the long-term economic impact of these two programs on citrus, grape and nursery producers. The net economic effects on all citrus producers and on grape producers in the southern San Joaquin Valley were insignificant, while all grape producers in the Temecula Valley saw an average increase in annual production costs of about $13.04 an acre. Based on our survey of nurseries in Southern California, approximately 11% had an infestation in 2008 and 2009, but only 3.0% in 2010. Average losses to nurseries per GWSS infestation were about $12,238. Nursery producers also undertook a variety of pest control methods to prevent infestations and plant losses, and to meet quarantine regulations. Average annual per-acre costs of these approaches were $2,975 for barrier methods to prevent GWSS from entering a premises, $1,032 in pesticide controls and $1,588 for in-house monitoring. [ABSTRACT FROM AUTHOR]

Highlights: [•] We investigated nursery tree offerings from 1900 to 2010 in Los Angeles County. [•] The diversity offerings increased significantly. [•] Tree nursery offerings may provide insights about the diversity of urban trees. [Copyright &y& Elsevier]

Pallenis maritima is a small cushion-forming subshrub known from the Western Mediterranean region, extending to S. Portugal along the Atlantic Coast. It is reported here for the first time for California, being documented for the first time as growing outside of cultivation in North America. In Orange County, southern California, it has naturalized along the immediate coast on rocky shores and sea cliffs mostly within the salt-spray zone. Pallenis maritima is cultivated in California and likely escaped from residential gardens, commercial landscapes, nurseries, or similar sources. We cite voucher specimens, describe the habitat, and comment on presumed mode of introduction. A review of the taxonomy and nomenclature of the Asteriscus alliance is provided. Pallenis maritima is one of a growing number of salt-tolerant ornamental plants that have become naturalized recently in southern California. [ABSTRACT FROM AUTHOR]

Nearly 20% of the 1.8 million ha (4.5 million ac) around San Francisco Bay in California are protected. Many small-scale, site-specific nurseries produce plants used to restore sites in this area. To improve regional efficacy, the California Native Nursery Network has been established to provide a conversation conduit among growers and scientists to share information about native plant propagation, eliminate redundant work, and promote economic viability of the native plant nursery industry. This article details some of the initial steps taken to form the network. [ABSTRACT FROM AUTHOR]

Ramorum leaf blight, caused by Phytophthora ramorum, has reemerged at several California nurseries after removal of infested material. In many cases, reemergence was not associated with reintroduction of the pathogen and may be attributed to inoculum surviving in soil beds because P ramorum propagules can survive for over a year in soil. Using artificially infested soil in microcosms, fumigation and heat treatments were examined as potential eradicants of P ramorum from soil. Treatments with chloropicrin, Vapam, and iodomethane were effective in reducing P ramorum propagules below detection limits. Basamid was consistently effective only when fully incorporated into the soil. Application of Basamid (392 kg/ha) at infested ornamental nursery sites mirrored results from microcosm experiments, indicating that a tarp cover over treated soil is necessary for reliable efficacy. Dimethyldisulfide, 1,3-dichloropropene, and two formulations of hydrogen dioxide were less effective, resulting in only partial reduction of propagules. In heat treatments, P ramorum in soil microcosms remained detectable 42 days after microcosms were incubated at 30 and 22°C but was not detectable in soil heated above 40°C for 3 days. Results from a solarized field plot indicate that prolonged sublethal temperatures, between 35 and 40°C for 42 days, can be effective in eliminating detectable propagules of P ramorum. [ABSTRACT FROM AUTHOR]

The article presents gardens, landscapes and historic buildings in California that should be preserved. It describes the Sakai and Oishi nurseries in Stege/Richmond/El Cerrito. The "San Diego Union-Tribune" warns of a threat to Rancho Guejito in the town of Escondido in San Diego County owned by the Rodney Co. It provides information on the Marsh Building in Monterey.

Presents information on nurseries in Napa County, California. Features of the Soscol Nurseries managed and developed by brothers William Neely and Simpson Thompson; Varieties of plants offered at Tobin's Nursery owned by M. Tobin; Background on the Napa Valley Nurseries developed by fruit-grower and nursery man Leonard Coates.

Explores the aquatic nurseries in San Diego and Los Angeles, California. Characteristics; Growth conditions; Adaptability to environmental conditions.

Pesticides are a potential risk factor for childhood leukemia. Studies evaluating the role of prenatal and/or early life exposure to pesticides in the development of childhood leukemia have produced a range of results. In addition to indoor use of pesticides, higher risks have been reported for children born near agricultural crops. No studies have looked at pesticide exposure based on proximity of birth residence to commercial plant nurseries, even though nurseries are located much closer to residences than agricultural crops and can potentially result in chronic year-round pesticide exposure. To evaluate whether risk of childhood leukemia is associated with pesticide use as determined by distance of residence at birth to commercial, outdoor plant nurseries. We conducted a large statewide, record-based case-control study of childhood leukemia in California, which included 5788 childhood leukemia cases and an equal number of controls. Pesticide exposure was based on a spatial proximity model, which combined geographic information system data with aerial satellite imagery. Overall, the results supported an increased childhood leukemia risk only for birth residences very close to nurseries. For birth residences less than 75 m from plant nurseries, we found an increased risk of childhood leukemia (odds ratio (OR) 2.40, 95% confidence interval (CI) 0.99-5.82) that was stronger for acute lymphocytic leukemia (OR 3.09, 95% CI 1.14-8.34). The association was robust to choices of reference group, cut points and data quality. Our findings suggest that close proximity to plant nurseries may be a risk factor for childhood leukemia and that this relationship should be further evaluated. • First study about spatial proximity to commercial outdoor plant nurseries and childhood leukemia. • Geographic information systems (GIS) and historic aerial satellite imagery was utilized to determine spatial proximity between subjects and nurseries. • About three-fold increase in risk for ALL was observed among children in very close proximity (≤ 75 meters) to outdoor plant nurseries. [ABSTRACT FROM AUTHOR]

Susceptible day-neutral strawberry (Fragaria xananassa Duch.) cultivars are readily infected by Colletotrichum acutatum J.H. Simmonds during nursery propagation. The fungus infects strawberry flowers and fruit under warm, moist conditions and spreads rapidly throughout the nursery planting during repeated cycles of infection. Plants transplanted from infected nurseries into fruit-production fields have increased plant mortality and yield loss. This paper reviews practices adopted by California strawberry nurseries that reduce or eliminate sources of fungal inoculum, reduce strawberry plant susceptibility, or reduce pathogen spread in the nursery. California nurseries are currently using a combination of these practices to produce specific pathogen-free planting stock of susceptible day-neutral cultivars. [ABSTRACT FROM AUTHOR]

Over the past several years, plantings of California native plant nursery stock in restoration areas have become recognized as a pathway for invasive species introductions, in particular Phytophthora pathogens, including first in the U.S. detections (Phytophthora tentaculata, Phytophthora quercina), new taxa, new hybrid species, and dozens of other soilborne species. Restoration plantings may be conducted in high-value and limited habitats to sustain or re-establish rare plant populations. Once established, Phytophthora pathogens infest the site and are very difficult to eradicate or manage—they degrade the natural resources the plantings were intended to enhance. To respond to unintended Phytophthora introductions, vegetation ecologists took a variety of measures to prevent pathogen introduction and spread, including treating infested areas by solarization, suspending plantings, switching to direct seeding, applying stringent phytosanitation requirements on contracted nursery stock, and building their own nursery for clean plant production. These individual or collective actions, loosely coordinated by the Phytophthoras in Native Habitats Work Group ensued as demands intensified for protection from the inadvertent purchase of infected plants from commercial native plant nurseries. Regulation and management of the dozens of Phytophthora species and scores of plant hosts present a challenge to the state, county, and federal agriculture officials and to the ornamental and restoration nursery industries. To rebuild confidence in the health of restoration nursery stock and prevent further Phytophthora introductions, a voluntary, statewide accreditation pilot project is underway which, upon completion of validation, is planned for statewide implementation. [ABSTRACT FROM AUTHOR]

Recapture and recycling of irrigation water is often required to meet enormous water demands at horticultural nurseries. We tested four water types associated with a recycled irrigation system at a commercial container nursery in southern California for presence of oomycete plant pathogens from July 2015 to December 2017. These water types included: the main source of water originating from a reservoir, retention water from an on-site collection pond, irrigation water received by different growing areas within the nursery, and irrigation runoff captured in polyethylene sheet-lined runoff channels. The genera Phytophthora , Pythium , and Phytopythium together contributed more than 85% of the total oomycete population detected in the recycled irrigation system. The Phytophthora and Pythium genera were represented by member species from nine (1–4, 6–10) and eight (A, B, D-F, H-J) different sub-generic clades, respectively. Incoming water sourced from the reservoir was found to harbor known plant pathogens such as Phytophthora citricola -complex, P. capsici -cluster, P. tropicalis, P citrophthora -cluster, P. nemorosa -cluster, P. riparia , P. cryptogea -complex, P. parsiana -cluster, P. sp. nov. aff. kernoviae , Pythium dissotocum -complex , Py. oligandrum -cluster, Py. irregulare, and Phytopythium litorale. Runoff water showed the highest oomycete species richness and frequency of detection with both filtration and leaf baiting methods. In addition to plant pathogens, oomycete fish pathogens such as Aphanomyces laevis , Pythium chondricola -complex, Pythium flevoense -complex, and Saprolegnia diclina -complex were also detected in greater abundance in the recycled irrigation water. The oomycete species richness in the runoff water was correlated with several environmental parameters such as soil temperature. Greater oomycete richness in incoming water was associated with higher soil temperatures, whereas richness in runoff declines with increasing soil temperature, likely suggesting connections to weather-dependent nursery operations. • Identified oomycete populations in recycled irrigation water by metabarcoding. • Source of irrigation water harbors several oomycete plant and animal pathogens. • Recycled water is enriched with Phytophthora , Pythium , and Phytopythium species. • The highest number of oomycete species was detected in runoff water. • Oomycete diversity in runoff and incoming water correlated to weather parameters. [ABSTRACT FROM AUTHOR]

“TRAO FUNS” is a project to survey the Gould Belt’s clouds in molecular lines. This paper presents its first results on the central region of the California molecular cloud, L1478. We performed on-the-fly mapping observations using the Taeduk Radio Astronomy Observatory 14 m single-dish telescope equipped with a 16 multibeam array covering a ∼1.0 square degree area of this region using , mainly tracing low-density clouds, and a ∼460 square arcminute area using , mainly tracing dense cores. and were also used simultaneously to map a ∼440 square arcminute area of this region. We identified 10 filaments by applying the dendrogram technique to the data cube and 8 dense cores using FellWalker. Basic physical properties of filaments such as mass, length, width, velocity field, and velocity dispersion are derived. It is found that L1478 consists of several filaments with slightly different velocities. Particularly, the filaments that are supercritical are found to contain dense cores detected in . A comparison of nonthermal velocity dispersions derived from and for the filaments and dense cores indicates that some of the dense cores share kinematics similar to those of the surrounding filaments, while several dense cores have different kinematics from those of their filaments. This suggests that the formation mechanism of dense cores and filaments can be different in individual filaments depending on their morphologies and environments. [ABSTRACT FROM AUTHOR]

Phenotypic and sequence data were used to characterize 28 isolates resembling Phytophthora megasperma from 14 host species in 2 plant production facilities and 10 restoration sites across the San Francisco Bay Area (California; USA). Size of the oogonia and DNA sequences (nuclear internal transcribed spacer (ITS) and mitochondrial cytochrome c oxidase subunit 1 (COX 1)) were compared, and sensitivity to mefenoxam and pathogenicity were measured. Based on ITS 61 % of isolates matched ex-type sequences of Phytophthora crassamura from Italy, and the remainder matched or were close to the P. megasperma ex-type. However, all California P. crassamura genotypes belonged to four unique COX 1 haplotype lineages isolated from both nurseries and restoration sites. Although lineages were sensitive to mefenoxam, a significant difference in sensitivity was identified, and all continued growth in-vitro. These results suggested previous mefenoxam exposure in plant production facilities resulting in tolerance. In conclusion, all evidence pointed to a nursery origin of novel P. crassamura lineages found in California restoration sites. In this study, COX 1 sequences and oogonia size provided information relevant to identify geographic and evolutionary intraspecific variation within P. crassamura, and was additionally used to track the spread of this species from nurseries into wildlands., (Copyright © 2018 British Mycological Society. Published by Elsevier Ltd. All rights reserved.)