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Priming potato with thiamin to control potato virus Y
Get PDFPotato virus Y (PVY) is a major potato pathogen affecting potato yields worldwide. Thiamin, a water-soluble B vitamin (vitamin B1) has been shown to boost the plant’s immunity, thereby increasing resistance against pathogens. In this study, we tested different concentrations of thiamin (1 mM, 10 mM, 50 mM, 100 mM) and multiple thiamin applications (once, biweekly and monthly,) on potato resistance to PVY in Ranger Russet potatoes. Plants were mechanically inoculated with PVYN:O. This PVY strain is known for causing well-defined foliar symptoms. We collected leaflets weekly through April and May 2014 and tested them with an enzyme-linked immunosorbent assay specific to PVY as well as by real time quantitative RT-PCR. These assays allowed us to determine the presence and level of PVY in different parts of the plants. We found that the highest thiamin concentration treatment (100 mM) produced the lowest virus level in potatoes across all dates and leaflet samples. Also, it was found that multiple applications of thiamin had a positive effect on reducing virus level, especially when thiamin was applied every four weeks
Words are monuments: Patterns in US national park place names perpetuate settler colonial mythologies including white supremacy
Get PDF1. Ecologists, outdoor professionals and the public work and play in lands with complex histories. Part of decolonizing our professional and recreational practices is to expose settler colonial biases and recognize the histories of colonized lands and the peoples who have stewarded these lands for millennia prior to colonization.
2. To provide a quantitative example of settler colonial biases in a familiar context, we examined the origins of over 2,200 place names in 16 national parks in the United States (US; 26% of the parks). Through iterative thematic analysis of place name origins and meanings, we constructed a decision tree for classifying place names according to emergent categories, which enabled the quantification and spatial analysis of place name meanings.
3. All national parks examined have place names that tacitly endorse racist or, more specifically, anti-Indigenous ideologies, thus perpetuating settler colonialism and white supremacy at the system scale for future generations.
4. Looking east to west across the US, the proportion of place names per national park that appropriated Indigenous names increased in parallel with the westward expansion and evolution of US settler colonialism.
5. This examination of place names, name origins and their consequences is an opportunity to make everyday complicity in systemic oppression more visible and to more actively advance decolonizing practices for land and language
Resilience and resistance in sagebrush ecosystems are associated with seasonal soil temperature and water availability
Get PDFInvasion and dominance of exotic grasses and increased fire frequency threaten native ecosystems worldwide. In the Great Basin region of the western United States, woody and herbaceous fuel treatments are implemented to decrease the effects of wildfire and increase sagebrush (Artemisia spp.) ecosystem resilience to disturbance and resistance to exotic annual grasses. High cover of the exotic annual cheatgrass (Bromus tectorum) after treatments increases fine fuels, which in turn increases the risk of passing over a biotic threshold to a state of increased wildfire frequency and conversion to cheatgrass dominance. Sagebrush ecosystem resilience to wildfire and resistance to cheatgrass depend on climatic conditions and abundance of perennial herbaceous species that compete with cheatgrass. In this study, we used longer-term data to evaluate the relationships among soil climate conditions, perennial herbaceous cover, and cheatgrass cover following fuel management treatments across the environmental gradients that characterize sagebrush ecosystems in the Great Basin. We examined the effects of woody and herbaceous fuel treatments on soil temperature, soil water availability (13-30 and 50 cm depths), and native and exotic plant cover on six sagebrush sites lacking pinon (Pinus spp.) or juniper (Juniperus spp.) tree expansion and 11 sagebrush sites with tree expansion. Both prescribed fire and mechanical treatments increased soil water availability on woodland sites and perennial herbaceous cover on some woodland and sagebrush sites. Prescribed fire also slightly increased soil temperatures and especially increased cheatgrass cover compared to no treatment and mechanical treatments on most sites. Non-metric dimensional scaling ordination and decision tree partition analysis indicated that sites with warmer late springs and warmer and wetter falls had higher cover of cheatgrass. Sites with wetter winters and early springs (March-April) had higher cover of perennial herbs. Our findings suggest that site resistance to cheatgrass after fire and fuel control treatments decreases with a warmer and drier climate. This emphasizes the need for management actions to maintain and enhance perennial herb cover, such as implementing appropriate grazing management, and revegetating sites that have low abundance of perennial herbs in conjunction with fuel control treatments
Management controls and pressure groups : the mediation of overflows
Get PDFPurpose Organisations produce effects that go beyond the economic framing within which they operate, referred to as overflows in this paper. When an organisation comes under pressure to address these overflows they must decide how to respond. Previous research has placed social and environmental reporting as an important tool organisations mobilise in their attempts to mediate these pressures and the groups that give rise to them. However, these reports are typically only released once a year while the pressures that organisations face can arise at any time and are ongoing and constant. The purpose of this paper is to explore situated organisational practices and examine if and how management controls are mobilised in relation to the actions of pressure groups.
Design/methodology/approach This paper takes a case study approach to understand how an organisation attempts to mediate the pressures from a number of overflows: carbon emissions, changing lifestyles, aspartame and obesity. To undertake this research a performative understanding of management control is utilised. This focusses the research on if and how management controls are mobilised to assist with attempts to mediate pressures.
Findings Analysis of the data shows that many different management controls, beyond just reports, were mobilised during the attempts to mediate the pressure arising from the actions of groups affected by the overflows. The management controls were utilised to: identify pressures, demonstrate how the pressure had been addressed, alleviate the pressure or to dispute the legitimacy of the pressure.
Originality/value This paper shows the potential for new connections to be made between the management control and social and environmental accounting literatures. It demonstrates that future research may gain much from examining the management controls mobilised within the situated practices that constitute an organisations response to the pressures it faces
Modeling the Financial Potential of Silvopasture Agroforestry in Eastern North Carolina and Northeastern Oregon
Get PDFSilvopasture is the planned and managed agroecosystem in which forage, livestock, and woody perennials are integrated "either simultaneously or sequentially on the same parcel of land." Silvopasture can help mitigate anthropogenic climate change through carbon sequestration in perennial vegetation. We examined silvopasture, forest, and pasture systems in eastern North Carolina and northeastern Oregon. In North Carolina, we evaluated forest and agroforestry systems using loblolly and longleaf pine species. In Oregon, we evaluated forest and agroforestry systems using ponderosa pine. We based the analyses on typical forest and cattle regimes, including yields, costs, and prices obtained from the literature, and consulted with experts in the respective subjects. The financial viability of land management investments was investigated using capital budgeting techniques. Cash flows were developed using 4 percent and 6 percent real discount rates. Analysis suggests loblolly pine timber management and cattle management are more profitable than silvopasture management in eastern North Carolina. Additionally, cattle management is more profitable than silvopasture in northeastern Oregon. Longleaf pine and ponderosa pine are not profitable when solely managed for timber and can benefit financially when combined with livestock
The political biogeography of migratory marine predators
Get PDFDuring their migrations, marine predators experience varying levels of protection and face many threats as they travel through multiple countries' jurisdictions and across ocean basins. Some populations are declining rapidly. Contributing to such declines is a failure of some international agreements to ensure effective cooperation by the stakeholders responsible for managing species throughout their ranges, including in the high seas, a global commons. Here we use biologging data from marine predators to provide quantitative measures with great potential to inform local, national and international management efforts in the Pacific Ocean. We synthesized a large tracking data set to show how the movements and migratory phenology of 1,648 individuals representing 14 species-from leatherback turtles to white sharks-relate to the geopolitical boundaries of the Pacific Ocean throughout species' annual cycles. Cumulatively, these species visited 86% of Pacific Ocean countries and some spent three-quarters of their annual cycles in the high seas. With our results, we offer answers to questions posed when designing international strategies for managing migratory species
EMDUniFrac : exact linear time computation of the UniFrac metric and identification of differentially abundant organisms
Get PDFBoth the weighted and unweighted UniFrac distances have been very successfully employed to assess if two communities differ, but do not give any information about how two communities differ. We take advantage of recent observations that the UniFrac metric is equivalent to the so-called earth mover's distance (also known as the Kantorovich-Rubinstein metric) to develop an algorithm that not only computes the UniFrac distance in linear time and space, but also simultaneously finds which operational taxonomic units are responsible for the observed differences between samples. This allows the algorithm, called EMDUniFrac, to determine why given samples are different, not just if they are different, and with no added computational burden. EMDUniFrac can be utilized on any distribution on a tree, and so is particularly suitable to analyzing both operational taxonomic units derived from amplicon sequencing, as well as community profiles resulting from classifying whole genome shotgun metagenomes. The EMDUniFrac source code (written in python) is freely available at: https://github.com/dkoslicki/EMDUniFrac
Assessment of the Biological Control Potential of Common Carabid Beetle Species for Autumn- and Winter-Active Pests (Gastropoda, Lepidoptera, Diptera: Tipulidae) in Annual Ryegrass in Western Oregon
Get PDFMany studies have shown that ground beetles feed on different agricultural pests, but little is known about their species communities from US cropping systems. We assessed the biological control potential of the most common carabid beetle species in Oregon annual ryegrass grown for seed by investigating spatial and temporal overlap of the most common species with those of the most damaging autumn- and winter-active pests (slugs, caterpillars and cranefly larvae) and determined the number of field-collected specimens that had fed on the respective pests using molecular gut content analysis. Only the non-native Nebria brevicollis was abundant during pest emergence and tested positive for all three pest groups. While the other common carabid beetle species—Agonum muelleri, Calosoma cancellatum and Poecilus laetulus—were also found to have consumed pests, they were active only during spring and summer, when crop damage by pests is less critical. We also show that disk tilling did not affect any of the four common carabid beetle species and that only N. brevicollis was significantly associated with a vegetated field margin. This study contributes to expanding our knowledge on conservation biological control in a system where chemical pesticides are still the mainstay of control against invertebrate pests.Keywords: conservation biological control; slugs; qPCR; molecular gut content analysis; Nebria brevicollis; Noctua pronuba; Deroceras reticulatu
Optimizing management to conserve plant diversity and soil carbon stock of semi-arid grasslands on the Loess Plateau
Get PDFGrassland recovery from degradation is increasingly occurring worldwide. Diverse managements have been considered as effective ways to restore degraded grassland, but it remains unclear how semi-arid grasslands respond to long-term grazing exclusion and fenced mowing. Here, a study was conducted under open grazing, grazing exclusion and fenced mowing in a semi-arid grassland on the Loess Plateau. We measured plant species composition and diversity, plant production, surface litter and soil water and carbon content. Shifts in grassland management led to significant divergence in plant community composition. Long-term grazing exclusion (35 years) significantly increased plant biomass, surface litter, soil water and carbon storage, but suppressed plant diversity compared to open grazing. Conversely, fenced mowing significantly increased plant diversity accompanying with a weak effect on soil carbon. Moreover, mowing significantly reduced surface litter and soil moisture, which have strong implications for nutrient depletion and soil drying. Our results suggest that introducing disturbances are necessary to safeguard biodiversity, and continuous mowing (5 years) belongs to over exploitation of the long-term protected grassland. Therefore, it is essential to optimize management with dual objectives of biodiversity and soil carbon sequestration in the future
Susceptibility of Hop Crown Buds to Powdery Mildew and its Relation to Perennation of Podosphaera macularis
Get PDFIn the Pacific Northwestern United States, the hop powdery mildew fungus, Podosphaera macularis, survives overwintering periods in association with living host tissue because the ascigerious stage of the pathogen is not known to occur in this region. Field experiments were conducted over a 5-year period to describe the overwintering process associated with crown bud infection and persistence of P. macularis. Surface crown buds increased in abundance and size beginning in early July and continuing until mid-September. Buds of varying sizes remained susceptible to powdery mildew until late September to early October in each of 3 years of experiments, with susceptibility decreasing substantially thereafter. Potted plants were inoculated sequentially during early summer to autumn, then evaluated in the following year for development of shoots colonized by the powdery mildew fungus (termed flag shoots) due to bud perennation. Emergence of flag shoots was asynchronous and associated with shoot emergence and elongation. Flag shoots emerged over a protracted period from late February to early June, year dependent. In all 4 years of experiments, some infected buds broke and produced flag shoots after chemical desiccation of shoots in spring, a common horticultural practice in hop production conducted to set training timing and eliminate initial inoculum. Flag shoots were most numerous when plants were inoculated with P. macularis in early summer and, consequently, when powdery mildew was present throughout the entire period of crown bud development. The number of flag shoots produced was reduced from 6.8- to 46.6-fold when comparing the latest versus earliest inoculation dates. However, all inoculation timings yielded flag shoots at some level, suggesting that bud infection that occurs over an extended period of time in the previous season may allow the fungus to perennate. In studies in two commercial hop yards in Washington State, fungicide applications made after harvest reduced the level of powdery mildew on leaves in the current year but did not significantly reduce flag shoots in the following year. Given that bud infection occurred over a 10-week period, flag shoots developed even when plants were exposed to inoculum in October and some flag shoots survived chemical pruning practices, management efforts seem best directed to both preventative measures to reduce the likelihood of bud infection and remedial practices to physically eliminate infected crown buds in the ensuing year