Digital Commons Network^™

Identification Of Downy Mildew Resistance In Wild Arugula And Evaluation Of Downy Mildew Causing Pathogens And Management Practices, Reilly B. Blair

Master's Theses

Downy mildew has been a potentially devastating constraint to crop production within the Brassicaceae family worldwide (CABI, 2022) and on the Central Coast of California (Smukler, et al, 2008; Koike, et al. 2007). Downy mildew is a foliar disease, caused by the pathogens in the Hyaloperonospora genus on plants within the Brassicaceae family (Goker, et al, 2009). Downy mildew is a disease that is common in region of the world with Coastal climates that provide humidity and moderate temperatures (Sarahan, et al, 2017). Crops within the Brassicaceae family maintain a predominant role in agricultural systems worldwide (Cartea, et al, 2011) …

An Evaluation Of Sonderegger Pine Morphology, Kelsey Denise Shoemaker

Master's Theses

Sonderegger pine (Pinus x sondereggeri H.H. Chapm.), the naturally occurring hybrid of longleaf (Pinus palustris Mill.) and loblolly pine (Pinus taeda L.), is considered a producer of poor-quality wood due to observations of stem forking and a high number of large-diameter branches at maturity. Because landowners generally decline planting Sonderegger pine seedlings, nursery workers cull putative hybrids from longleaf pine seedling stock during lifting and processing. However, over the past 100 years, very few studies have quantified stem quality of Sonderegger pine. To gain a better understanding of the early growth and development of Sonderegger pine, evaluations of height, diameter …

Clonal Growth And Trait Variation In The Colorado Front Range: The Influence Of Elevation And Ecosystem, Jordan Conley

Master's Theses

Amid global climate change, exploring adaptive strategies among alpine flora, particularly through clonal growth, becomes critical for biodiversity conservation. This study aims to explore the patterns of dominance and distributions among clonal species across environmental gradients in the Colorado Front Range, employing a trait-based comparative analysis to understand the adaptive strategies of alpine flora and their implications for conservation amid rapid climate change. We focused on two species, studying traits like lateral spread, bud count, and bulbil numbers. Advanced statistical methods such as Permutational Multivariate Analysis of Variance (PerMANOVA) and Multi-Response Permutation Procedures (MRPP) were used to evaluate community compositions …

Clonal Plants' Traits And Responses Following Fire Disturbance In Ponderosa Pine Ecosystems In The Colorado Front Range, Raymond Erskine

Master's Theses

Mountain ecosystems are currently experiencing increasing impacts of disturbances (e.g., wildfire) due to global changes in climate and land use, leading to significant changes in vegetation composition and landscape dynamics. Clonal plants, characterized by their vegetative reproduction strategies, offer a range of ecologically important traits to cope with disturbances. However, clonality is often excluded in studies of post-fire vegetation dynamics in mountain ecosystems, and our knowledge of the ability of clonal plants to respond to differing disturbance regimes is limited. Therefore, I examined the response of understory vegetation following fire disturbance in burned and unburned ponderosa pine stands of the …

Salinity Tolerance Of Flowering Rush, Butomus Umbellatus, Andrew Coomes

Master's Theses

Flowering rush is an invasive aquatic plant in North America that causes deleterious effects to native ecosystems. There are two cytotypes, a triploid and diploid, and multiple genotypes contained within the diploid cytotype currently established in the U.S. Despite its presence in river drainages connected to estuarine areas, documentation on the salinity tolerance of flowering rush is scarce. Currently, information is limited to anecdotal reports suggesting intolerance to saline conditions. A better understanding of the osmotic tolerance of this species is essential to providing insight into its’ invasive range and better inform management efforts. These studies investigated vegetative propagule germination …

Automated Tree Mortality Detection Using Ubiquitously Available Public Data, Michael T. Huggins

Master's Theses

Understanding the dynamic interplay between fire severity, topography, and tree mortality, is crucial for predicting future forest dynamics and enhancing resilience against climate change-induced wildfire regimes. This thesis develops a multi-sensor approach for automated estimation of tree mortality, then applies it to examine trends in tree mortality over a six-year period across a fire affected study site in the Trinity River basin in Northern California. The Random Forest model uses publicly available USGS 3D Elevation Program Lidar (3DEP) and NAIP imagery as inputs and is likely to be easily adaptable to other landscapes. The model had a Receiver Operating Characteristic …

Evaluating Habitat Use By Nekton In Widgeon Grass (Ruppia Maritima), Shoal Grass (Halodule Wrightii), And Unvegetated Bottom Habitats In The Grand Bay National Estuarine Research Reserve, Jessica Woodall

Master's Theses

Seagrass beds support high biodiversity and animal abundance, serve as feeding grounds for a variety of animals, offer shelter from predation, and act as a nursery habitat for juveniles. The species composition of seagrass beds can impact their use as habitat by animals. Two common species of seagrass in the Gulf of Mexico are Ruppia maritima (widgeon grass) and Halodule wrightii (shoal grass). The shallow coastal waters of the Grand Bay National Estuarine Research Reserve (NERR) support both species, but the use of each seagrass as habitat by nekton is poorly understood, which can limit management decision-making. Nekton communities were …

Evaluating The Field Efficacy Of Uv-C On Two California Strawberry Arthropod Pests, Jose Luis Alvarado Rojas

Master's Theses

The efficacy of two different autonomous Ultraviolet-C (UV-C) units on two spotted spidermite, Tetranychus urticae Koch (Acari: Tetranychidae), and greenhouse whitefly, Trialeurodes vaporariorum. (Hemiptera: Aleyrodidae). was tested in four commercial strawberry fields in California.

In 2020, California strawberry growers used 12 million pounds of active ingredients (AIs) to keep pests under economic thresholds. While pesticides are an important part of an integrated pest management program, their use poses threats to the environment and human health. To protect agricultural workers, the public and the environment, regulators in California have consistently limited or removed the use of certain pesticide AIs. For …

Comparative Analysis Of Rhizosphere And Endosphere Microbiome Of Different Blueberry Species (Vaccinium Sp.), Niladri Bhowmik

Master's Theses

Blueberries are an important agricultural commodity in all over the United States. Due to its health benefits, there is a huge demand globally, thus expanding the industry. Breeding programs are essential to maintain such industries. Challenges that play a role in contemporary breeding programs are various biotic and abiotic stress factors. Studies have shown that microorganisms are recruited by plants to alleviate them during stressful conditions. Though blueberries have been cultivated for about 100 years, how the microbiome has been affected due to this is poorly understood. We hypothesized that interspecific crosses and artificial selection have significantly changed the microbiome …

Lichens Of Ultramafic Rocks: A Multidisciplinary Approach To Understanding The Ecology Of An Understudied Organism In A Well-Studied System, Michael Mulroy

Master's Theses

Lichens are among the most prominent and successful life forms of metal-rich habitats, including ultramafic rocks and soils; however, research on lichens of ultramafic habitats is limited, especially on the North American continent. A review of the published literature on lichens of ultramafic substrates in North America yielded a total of 437 lichen species reported from ultramafic rocks and soils. Lichen assemblages of ultramafic substrates vary in composition and are dominated by acidophytic (low pH preferring) taxa with a minor, but consistent, basiphytic (high pH preferring) component. Species lists from ultramafic habitats in different geographic regions varied widely, suggesting that …

Determination Of Fungicide Resistance In Botrytis Cinerea On Wine Grapes In California's Central Coast Region, Evelyn Alvarez-Mendoza

Master's Theses

Botrytis bunch rot, caused by Botrytis cinerea, is a fungal disease that primarily affects the fruit of wine grapes. Infection of fruit consequently results in reduced yields and wine quality. These factors lead to significant economic losses for growers which prompts the implementation of management practices to control the disease. One objective of this study was to evaluate the level of resistance that populations of B. cinerea in the Central Coast region showed to various chemicals. A fungicide assay was conducted to determine resistant phenotypes to six fungicide active ingredients (pyrimethanil, iprodione, fenhexamid, fludioxonil, trifloxystrobin, boscalid). Thirty-five (2020) and …

Seed Longevity And Climatic Tolerance Of San Joaquin Wooly-Threads (Monolopia Congdonii; Asteraceae) An Endangered Plant From The San Joaquin Desert, California, Paul Excoffier

Master's Theses

San Joaquin wooly-threads (Monolopia congdonii; Asteraceae) is a federally-listed, endangered annual plant species from the desert areas of the San Joaquin Valley. Its limited range puts it at risk of extinction if the climate changes in such a way as to hinder its growth and reproduction. The primary aims of the study were to 1) determine how long-lived the seeds of the M. congdonii are, a key determinant of survival of desert annual plant populations through long droughts and 2) determine how severely hotter, drier conditions impact the ability of emerged plants to grow and reproduce. Secondarily, I …

Reassessment Of Species Boundaries And Phylogenetic Relationships In The Desmodium Ciliare Complex (Fabaceae) Using Morphological And Dna Data, Joshua Wilkinson

Master's Theses

Desmodium (Beggar's ticks) is a generally weedy genus of approximately 280 species in the angiosperm family Fabaceae (Subfamily Papilionoideae, Tribe Desmodieae) characterized by indehiscent loments constricted into segments. Within the Southeastern U.S., the Desmodium ciliare group is one of two Desmodium species complexes that have been historically difficult, with much argument about the limits of species and the role of hybridization. There are three commonly recognized species within the D. ciliare group, D. ciliare (Muhl. ex Willd.) DC., Desmodium marilandicum (L.) DC., and D. obtusum (Muhl. ex Willd.) DC., with two supposed hybrids in addition to the …

A Comparison Of Natural, Living, And Hardened Shorelines Ability To Prevent Coastal Erosion And Maintain A Healthy Ecosystem, Gabrielle Spellmann

Master's Theses

It is important to find a suitable method to protect the U.S. Gulf Coast shoreline, since its’ low elevation and the Loop current make it vulnerable to sea level rise. I focused on two manmade methods, hardened, and living shorelines, of coastal protection for when the natural marsh suffers excess erosion rates. Living shorelines are a suite of shoreline conservation and restoration techniques that usually involve some sort of hardened structure that dampens wave energy so that the native vegetation behind it can take root and stabilize the shoreline. This study looked at six different sites, all containing a natural, …

Healing Sanctuary, Kammy Downs

Master's Theses

The natural world has hidden wisdom and resources that are disregarded as we misuse our responsibility to care for them. The benefits of being in tune with nature have been traded for a culture that manipulates nature on the altar of expediency, waste, and unquenchable desire. Healing Sanctuary presents a duality. My work speaks about the relationship between the seen and unseen, represented by ten larger-than-life drawings of medicinal herbal plants that have had a profound physical healing effect on me. At the same time, plants, roots, and seeds create visceral metaphors for mental health. Our accomplishments, outlook on life, …

Effects Of Nitrogen Management And Cultivar On Strawberry Production Under Disease Pressure, Kamille A. Garcia-Brucher

Master's Theses

Effects of nitrogen management and cultivar on strawberry production under disease pressure

Kamille Garcia-Brucher

California strawberry growers face increasing regulatory pressures to manage nitrogen (N) applications in their production system. Standard practice in the California strawberry industry is to apply a synthetic pre-plant controlled release fertilizer (CRF) to ensure the crop has sufficient N during winter establishment. Some research from the UC Cooperative Extension suggests this practice is not efficient at delivering N to the crop since most of the N is released from CRF before strawberry crop N uptake is significant. Another concern for California strawberry growers is loss …

Climate Adaptation And Water Conservation Decision-Making In Paso Robles, California Vineyards, Christopher R. Klier

Master's Theses

This paper examines vineyard perceptions and adoption of climate change adaptation and water conservation measures in the Paso Robles American Viticultural Area (AVA). A survey was distributed to all 220 vineyards and vineyard management companies that operate in the AVA, with a 53.64% response rate. The objective of the survey was to determine vineyard manager and owner attitudes towards climate change and adaptation, as well as their perceptions of how these threats would impact their operation. A second objective was to document the current level of water conservation and climate adaptation while identifying the barriers and opportunities for further adoption …

Effects Of Compost On Soil Health And Greenhouse Gas Emissions: A Case Study In A Mediterranean Vineyard, Tsz Fai Wong

Master's Theses

Compost is commonly used as an organic amendment in cropping systems such as vineyards, and has been shown to be beneficial to carbon (C) sequestration and soil health. As perennial crops, grapevines have a larger potential for C sequestration than most crops. Yet, there is a lack of understanding regarding the relationship between compost application rate, the magnitude of C sequestration, and its environmental tradeoff in the form of greenhouse gas (GHG) emissions. In the study, we investigated the effects of compost application rate on soil C sequestration, GHG emissions, crop growth, and overall soil health after two annual compost …

Reciprocal Transplant And Machine Learning Study Of Oak Mistletoe On Three Host Oak Species In Santa Margarita, California, Ella Abelli-Amen

Master's Theses

At Santa Margarita Ranch, California, oak mistletoe (Phoradendron villosum) parasitizes valley oak and blue oak but cannot be found growing on coast live oak despite its abundance and ability to parasitize coast live oak in other areas. It seems as though this species of mistletoe is specializing on certain host oak trees, but the mechanisms of this specialization are unknown. In order to investigate this pattern, we utilized a type of machine learning in GIS called supervised classification as well as a reciprocal transplant study in the field. The three species of oak trees were classified with 87% accuracy using …

Evaluation Of Masculinization Treatments To Produce Feminized Hemp Seed (Cannabis Sativa L.), Ted Fitzgerald, J. Wyatt Brown

Master's Theses

Cannabis sativa L. (hemp) develops plants with either male or female flowers, and growers of hemp greatly prefer female flowers which bear the glandular trichomes that contain cannabinoids. Feminized (all female) seeds are highly desired, which are produced by crossing a female plant with a masculinized female plant. Masculinization is achieved through the inhibition of ethylene and/or addition of gibberellins before flower initiation in female plants. The hemp industry uses silver thiosulfate (STS) to masculinize hemp, but spraying silver poses environmental concerns. This study compared STS to three other ethylene-inhibiting agents: aminoethoxyvinylglycine (AVG), cobalt nitrate (CBN), and 1-methylcyclopropene (1-MCP). Treatments …

Testing The Climatic Variability Hypothesis With Coastal And Inland Populations Of Mimulus Guttatus And Implications For These Populations Under Climate Change, Alec Chiono

Master's Theses

How climate shapes the niche of a species is a core interest in evolution and ecology. Research on the evolution of climatic niches can inform us on the historical relationship between organisms and their climate, and, in an era of great environmental change, what that relationship may look like in the future. In this study, I tested an essential idea in the history of climate niche research, the Climatic Variability Hypothesis, by comparing the thermal niche breadth of coastal and inland populations of Mimulus guttatus. Using thermal performance results from this experiment, I also forecasted how the suitability of …

Loblolly Pine (Pinus Taeda) Leaf-Level Physiology And The Influence Of Genotype, Drought, And Thinning, Norman Jesse Cone Iv

Master's Theses

The Southeastern U.S. is known as the “Wood Basket” for producing the vast majority of U.S. timber, but projected increases in the frequency of severe drought events could threaten timber plantations. Loblolly pine (Pinus taeda) is the principle timber species of the southeast and is distributed across the Atlantic Coastal Plains and west into Texas. Western Gulf states (LA, TX, AR, and OK) lie at the edge of the range for loblolly pine and are particularly vulnerable to any changes in precipitation or temperature. Current research suggests two main methods to increase plantation drought resistance: plant drought resistant seedlings or …

Evaluation Of Methods For The Restoration Of Native Grasslands On Abandoned Center Pivots In The Sandsage Prairies Of Southwestern Kansas, Alonso Barragan-Martinez

Master's Theses

Throughout southwestern Kansas thousands of acres of native grassland have been converted to cropland for agricultural use, reducing native prairie by over 60% in the sandsage prairie. Due to low precipitation and arid conditions, much of these croplands are irrigated by center pivot irrigation systems fed by the Ogallala Aquifer. These fields are abandoned when the aquifers dry up, resulting in erosion of the unused farmland. Conservation programs such as the Conservation Reserve Enhancement Program (CREP) were established to address this problem but have been unsuccessful in restoring native grasslands in abandoned croplands in southwestern Kansas. We hypothesized that insect …

Estimating Food Waste Due To Food Safety Recalls And Investigating Ways To Minimize Negative Impacts, Mykayla Latronica

Master's Theses

For years the issue of food waste has been recognized and quantified; however, food safety issues often go unrecognized as a source of food waste. One objective of this research is to estimate quantities and monetary value of fruits and vegetables implicated in food safety recalls, and thus wasted. Using publicly available data we identified all recalls involving vegetable or fruit commodities contaminated with Listeria monocytogenes, pathogenic E. coli, or Salmonella during 2015-2018. When quantities were provided, monetary value of recalled product was calculated using USDA ERS 2016 average retail prices. Although data limitations only allowed analysis of …

Strawberry Powdery Mildew Caused By Podosphaera Aphanis: Fungicide Resistance And Host Plant Resistance, Michael G. Palmer

Master's Theses

Strawberry powdery mildew, caused by Podosphaera aphanis, affects leaves, fruit, and runners of strawberry plants. Infected leaves have reduced photosynthetic capability and infected fruit become unmarketable. Both of these factors translate to economic loss for the grower and therefore merit taking measures to control the disease. One objective of this study was to evaluate the resistance developed in populations of strawberry powdery mildew to chemical control measures. A fungicide assay was developed to evaluate the efficacy of six treatments (penthiopyrad, quinoxyfen, myclobutanil, trifloxystrobin, cyflufenamid, fluopyram + trifloxystrobin) for control of the disease. Nineteen isolates of strawberry powdery mildew were …

Sensory Stressors Impact Species Responses Across Local And Continental Scales, Ashley A. Wilson

Master's Theses

Pervasive growth in industrialization and advances in technology now exposes much of the world to anthropogenic night light and noise (ANLN), which pose a global environmental challenge in terrestrial environments. An estimated one-tenth of the planet’s land area experiences artificial light at night — and that rises to 23% if skyglow is included. Moreover, anthropogenic noise is associated with urban development and transportation networks, as the ecological impact of roads alone is estimated to affect one-fifth of the total land cover of the United States and is increasing in space and intensity. Existing research involving impacts of light or noise …

Attractiveness Of English Thyme (Thymus Vulgaris L.) To Arthropod Natural Enemies And Its Suitability As A Dual Use Resource, Kristina K. Van Wert

Master's Theses

Current agroecosystem management practices have a negative effect on natural enemies and their ability to control insect pests. Conservation biological control through the addition of flowering resources can manage food resources for natural enemies. These floral resources can also provide multiple ecosystem services. Study goals were to determine if perennial Thymus vulgaris L. was attractive to natural enemies and if so, could it be a dual use resource encouraging pest management and providing harvestable product. In 2018 plots in three locations were used to examine the effect of habitat throughout the growing season on the attractiveness of T. vulgaris. …

Vegetative Community And Health Assessment Of A Constructed Juncus-Dominated Salt Marsh In The Northern Gulf Of Mexico, Nickolas R. Murphy

Master's Theses

Deer Island is a coastal habitat which provides a buffer from storm and flood damage as well as shore-line stabilization to the mainland of Biloxi, Mississippi. A third of the land has been lost since 1850, largely driven by tropical storm and hurricane impacts as well as sea level rise. The United States Army Corps of Engineers and Mississippi Department of Marine Resources have targeted the shores of the island as sites for restoration using beneficial use dredged material, and two sites of differing age have since been planted with Spartina alterniflora, Juncus roemerianus, Uniola paniculata, S. patens, and Panicum …

Valorization Of Carrot Processing Waste, Alexandra M. Duval

Master's Theses

Commercial carrot processors produce up to 175,000 tons of carrot waste annually. Carrot Mash (CM) is the term referring to the waste by-product of peeled baby carrot processing. Transportation of carrot processing waste is expensive due to its high- water content (approx. 83-95%). High in bioactive compounds (carotenoids) and dietary fibers, it is expected that its conversion into a value-added by-product is of interest to the carrot processing industry. Hemicellulose-rich plant materials have proven to be a source of oligosaccharides, which are known for their beneficial prebiotic activity. The objectives of this research were to: 1) determine the effect of …

The Influence Of Land Use On The Pollen Diet Of Honey Bee (Apis Mellifera) Colonies In Ellis County, Kansas, Ryan Engel

Master's Theses

Pollinators are integral to plant ecology as well as to worldwide food availability and security. Understanding how human-driven land use change impacts the nutrition of managed honey bees is important in pollinator conservation efforts and can contribute towards combating recent pollinator declines. The objective of this study was to determine sources of forage for honey bees across different land use types in Ellis County, Kansas, through pollen analysis and taxonomic identification. Replicate study colonies were placed in three separate land use types: Urban, Cropland, or Native/Semi-native prairie. Pollen was sampled every 7 to 14 days throughout a growing season (April …