Digital Commons Network^™

Reducing Scope 3 Emissions By Investing In Regenerative Agriculture In Supply Chains, Stephanie Cain

Master's Theses

The agricultural industry has an opportunity to shift to a more sustainable practice that helps restore vital topsoil, improve water quality, reduce environmental impact, and sequester atmospheric carbon into the vast soil carbon pool. However, to implement these practices at considerable scale, agricultural producers require access to resources and capital they rarely have and can be difficult to acquire. As a company, investing in regenerative agriculture in supply chains can lead to reduced Scope 3 emissions, more resilient supply chains, and better marketability as an investment fund, an employer, and a brand. Insetting regenerative agriculture can protect supply chains against …

An Integrated Approach For Controlling Verticillium Wilt Of Strawberry, Jack T. Koster

Master's Theses

Strawberry (Fragaria x ananassa, Duch.) is an important crop in California, with more than 35,000 acres planted in 2018 resulting in a farm gate value of $3.1 billion. In 2020, California strawberry production accounted for more than 85% of national strawberry production and faces serious threats to production due to various soil-borne diseases. One such disease, Verticillium wilt, is caused by the fungal pathogen Verticillium dahliae and is commonly found in temperate zones around the world where strawberries are grown. Due to the phase-out of efficacious fumigants like methyl bromide, alternative disease management methods have become necessary to …

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 …

Cofermentation, Post-Alcoholic, And Post-Malolactic Fermentation Blending Of Malbec, Merlot And Petite Sirah Wines, Armando Arturo Vega-Osorno

Master's Theses

A two-year study was conducted to assess the effects of cofermentation on red wine varietals. During the winemaking process, wines can be made from two or more varieties by picking, crushing and fermenting them together, a practice known as cofermentation. They can also be blended either after the completion of alcoholic fermentation or after malolactic fermentation. In the first year of the study, two grape varieties, Merlot (Mer), and Malbec (Mal) were cofermented. On the second year, a third varietal, Petite Sirah (PS) was also studied. Cofermented wines containing every possible binomial combination of the varietals was made and one …

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 …

The Effects Of Vine Age On Vine Performance, Fruit, And Wine Composition Of Zinfandel In The Templeton Gap Ava, California, Vegas L. Riffle

Master's Theses

A two-year study was conducted at a commercial vineyard in California’s Templeton Gap AVA to evaluate the effect of vine age on viticultural, enological, and sensory attributes of Vitis vinifera L. cv. Zinfandel grapes and wines. The experimental block was dry farmed, conventionally managed, with own-rooted Zinfandel vines that, when determined unproductive, were replaced with new vines of genetically identical scion plant material grafted onto St. George (Vitis rupestris Scheele) rootstock. Treatments included Young vines (5 to 12 years old), Control (representative proportion of young to old vines in the block), and Old vines (40 to 60 years old). …

Cattle Producer Motivations And Willingness To Participate In Industry Animal Welfare Program Verification, Chase Decoite

Master's Theses

As consumers have become increasingly interested in where their food comes from and how it is grown, the cattle and beef industry is without exception. Many consumers are beginning to question traditional animal husbandry practices and on-farm animal welfare protocol. It is essential that the food system meets new demands and understands consumer views. In order to address these concerns, the industry has rallied around the Beef Quality Assurance (BQA) program to set the standard for cattle welfare and beef quality, with the explicit goal of improving consumer confidence. The goal of this research is to determine if cattle producers …

Effects Of Plant Growth-Promoting Bacteria And Fungi On Strawberry Plant Health, Fruit Yield, And Disease Susceptibility, Mary Maher

Master's Theses

Studies on plant growth-promoting rhizobacteria (PGPR) and fungi (PGPF) as biostimulants have shown significant positive effects on plant health, fruit yield, or pest management. However, very few published studies to date have been specific regarding their effects on strawberries (Fragaria × ananassa), particularly on soilborne disease prevalence in organically grown strawberries. Empirical data on the results of using these products in commercial growing applications under various conditions would be highly valuable, especially for organic growers who have limited synthetic chemical pesticides, herbicides and fertilizers registered for use. The objective of this study is to evaluate the efficacy of …

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 …

Eelgrass (Zostera Marina) Population Decline In Morro Bay, Ca: A Meta-Analysis Of Herbicide Application In San Luis Obispo County And Morro Bay Watershed, Tyler King Sinnott

Master's Theses

The endemic eelgrass (Zostera marina) community of Morro Bay Estuary, located on the central coast of California, has experienced an estimated decline of 95% in occupied area (reduction of 344 acres to 20 acres) from 2008 to 2017 for reasons that are not yet definitively clear. One possible driver of degradation that has yet to be investigated is the role of herbicides from agricultural fields in the watershed that feeds into the estuary. Thus, the primary research goal of this project was to better understand temporal and spatial trends of herbicide use within the context of San Luis …

Improving Sustainable Fertilizer Practices For Pomegranate By Leaf Nutrient Concentration Evaluation And Fertilizer Trials, Minh Le

Master's Theses

Fruit tree leaf nutrient concentrations are commonly used to determine fertilizer rates, but information is limited regarding nutrient requirements, seasonal N uptake and removal rates, and soil N dynamics for pomegranate. Relationships between fertilizer rates, leaf nutrient concentrations, fruit yield and quality were examined in five mature, commercial California ‘Wonderful’ pomegranate orchards. Site 1 was observed for two growing seasons (2018-2019) and sites 2-5 were observed for one season (2018 or 2019). In 2018, 150, 300, or 450 g N/tree was applied at sites 1-3 in a single application at early fruit development or in two equal applications at early …

Maturation And Culture Media Effects On In Vitro Bovine Embryo Developmental Competence, Ciara M. Helland

Master's Theses

In vitro produced bovine embryos are critical to the cattle industry. However, these embryos have altered morphology, epigenetics, and metabolism when compared to their in vivo counterparts. The aim of this thesis was to alter maturation and culture media to improve the developmental competence of in vitro bovine embryos. This thesis is comprised of three experiments and one proof of concept study. Each experiment followed the same general layout: oocyte aspiration from Jersey or Holstein ovaries, oocyte maturation for 24 hours, fertilization with bull semen for 24 hours, then embryo culture for 7-8 days in 38.5 °C in 5% O …

Fruit, Flower, And Thorn: A Phenological Study Of 'Wonderful' Pomegranate, Kylie M. Mendonca

Master's Theses

‘Wonderful’ pomegranate flowering and fruiting habits are not well understood. Characterizing any relationship between flowering habit and fruit size and quality could lead to effective cultural practices for producing high-value fruit. Five mature ‘Wonderful’ pomegranate trees were monitored every 5-14 days throughout the 2015 growing season. Newly emerged flowers were tagged and characterized with respect to sex (determined by ovary shape and style length at anthesis), clustering habit, age of wood on which floral buds were borne, and direction of wood growth. More than 1,100 hermaphroditic flowers were identified and ovary/fruit diameter was recorded throughout the season. In addition to …

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 …

Evaluation Of Pheromone Mating Disruption For California Red Scale Control In Commercial California Citrus, Joel Timothy Leonard

Master's Theses

California red scale (CRS), Aonidella aurantii, is an increasingly injurious insect pest for the California citrus industry due to insecticide resistance, changing weather patterns, and shifting trade regulations. The presence of the insect on fruit, damages the rind of the fruit and high populations can cause dieback of branches as well as lower yields. Pheromone mating disruption of CRS has the potential to alleviate population control concerns and reduce insecticide use. The efficacy of the pheromone mating disruption technique for pest management of CRS was determined using the products CheckMate® CRS and Semios CRS Plus. CheckMate® CRS was evaluated …

The Effects Of Cluster Thinning On Vine Performance, Fruit, And Wine Composition Of Pinot Noir (Clone 115) In The Edna Valley Of California, Paul F W Mawdsley

Master's Theses

A three-year study was conducted at a commercial vineyard site in California’s Edna Valley AVA to evaluate the physiological and agronomical effects of the timing of cluster thinning on Pinot noir (clone 115) grapevines. Vines were thinned to one cluster per shoot at three selected time-points during the growing season (bloom, bloom + 4 weeks, bloom + 8 weeks), and fruit from each treatment was harvested and made into wine. Across all growing seasons, yield decreased 43% in thinned vines relative to un-thinned control vines. No effect of cluster thinning or interaction with growing season was found in vine shoot …

Effects Of Sudangrass Cover Crop And Soil Solarization On Weed And Pathogen Management In Organic Strawberry Production, Timothy Jacobs

Master's Theses

Field and lab experiments were conducted to determine the efficacy of sudangrass (Sorghum X drumondii (Nees ex Steud.) Millsp. & Chase) cover crop management techniques and soil solarization on important agricultural weeds and pathogens in organic strawberry production in Central California. Lab experiments assessed the time needed to kill weed seeds at temperatures typically achieved during soil solarization (40°C, 45°C, 50°C, 55°C, and 60°C) in California. Seeds tested included little mallow, redstem filaree, bristly oxtongue, annual sowthistle, common purslane, nettleleaf goosefoot, and redroot pigweed. Efficacy of simulated …

Evaluation Of Host Resistance And The Utilization Of Organic Amendments To Manage Macrophomina Crown Rot Of Strawberry In California, Jonathan W. Winslow

Master's Theses

The production of strawberries can be severely limited by soilborne plant pathogens, insects and weeds. Macrophomina phaseolina is a problematic soilborne fungal pathogen in California strawberry production inciting the disease Macrophomina crown rot. When established, the pathogen can cause extensive plant decline and mortality. Host resistance will be a critical tool for managing this disease and guiding breeding programs in the post methyl bromide era. Evaluation of host resistance in strawberry germplasm to M. phaseolina was evaluated through phenotypic assessments of disease incidence. A total of 90 strawberry cultivars and elite selections were included in a replicated field trial conducted …

Effectiveness Of Windrow Composting Methodology In Killing A Thermo-Tolerant Species Of Salmonella During Mortality Composting, Spencer Gabriel Myers

Master's Theses

In a large agricultural operation, such as the one at Cal Poly San Luis Obispo, disposal of deceased animals is an immense issue. The cost of transporting and rendering every dead animal is inhibitory to the general function of the agricultural operations and their thin budget. Therefore, we propose that composting mortalities could be an economical alternative. Composting is a recognized method for taking animal waste products along with carbon waste and turning it into a pathogen-free, nutrient-rich topsoil. Carcass composting is in fact performed in other countries and states to varying degrees of success. However, the California EPA limits …

An Assessment Of The Greatest Impacts On Distribution Uniformity For Drip And Micro Irrigation, Brooke Ashley Worden

Master's Theses

Using the Cal Poly Irrigation Training and Research Centers (ITRC) drip/micro evaluation program, global, or system, DU_lq is computed by combining the component DU_lq values of: pressure variation, uneven spacing between emitters, unequal drainage and “other” causes. “Other” causes include plugging, wear and manufacturing coefficient. The program also computes what percentage of the non-uniformity is due to each component. Burt (2004) showed that over 95% of the non-uniformity is due to “Other” causes and pressure differences. This thesis looks at what specifically in those components is driving the non-uniformity by analyzing various equipment and field practices and their …

Assessment Of Granulovirus, Spinosad, And Mating Disruption For Controlling Cydia Pomonella L. [Lepidoptera: Tortricidae] In Organic Coastal California Apple Orchards, Raven Lukehart

Master's Theses

Codling moth, Cydia pomonella[Lepidoptera: Tortricidae], is a major entomological pest of apples, pears, and walnuts cross the world (Pajac et al. 2016). Female codling moths lay eggs on the apple exocarp and larvae burrow within the fruit causing economic losses to fruit growers.Organic apple orchards in San Luis Obispo, CA currently have three codling moth, Cydia pomonella,control options commercially available including granulovirus (CpVG), spinosad, and mating disruption. In field tests on apple (Malus), we compare percent fruit injury between treatments of granulovirus (2.43 oz/ha Cyd-X® organically approved, Certis USA, Columbia MD), spinosad (4.05 oz/ha Entrust® Naturalyte® …

Analysis Of Potential Vermicompost Market In California, Jason Alan Thomas

Master's Theses

Vermicompost transforms agricultural waste into a high quality soil amendment, though market acceptance remains in its infancy. This study examines how growers’ willingness to pay for vermicompost is affected by grower’s crop, region, income per acre, knowledge level of vermicompost and compost, previous use of compost, and the willingness to pay for compost. The survey results pulled together 223 responses from California growers. It was discovered growers’ had less knowledge of vermicompost than compost but were willing to pay more for vermicompost. There was statistical difference amongst the responses. It was shown the market value per ton of vermicompost lies …

What’S At Steak? The Political Discourse Of Emissions Intensity And Implications Of Animal Agriculture, Kalyn Simon

Master's Theses

This thesis analyzes the international discourse of greenhouse gas emissions in relation to livestock production. Specific government ministries, research institutes, and multilateral organizations are framing a new strategy to mitigate emissions by using emissions intensity metrics. Emissions intensity is a ratio comparing emissions produced per unit of animal product as oppose to measuring absolute emissions. This research is acknowledged as a win-win scenario which allows for a reduction of greenhouse gas emissions while continuing production more efficiently. This thesis outlines the emergence of this metric in international discourse and the implications this shift has on the livestock sector globally. Ultimately, …

Plant Compound Pest Control In California Strawberry (Fragaria × Ananassa) Production, Eli Mahanes Weissman

Master's Theses

Allelopathy occurs when one organism releases a compound into the environment that affects the functioning of another organism. Scientists have long suspected that alleopathic plant compounds could offer novel, softer chemistries to the ongoing battle of controlling pests in agricultural fields. Strawberry growers rely on toxic fumigants to kill soilborne fungal pests, weeds, nematodes, and insects. Increased regulations have reduced the use of fumigants (including methyl bromide), and strawberry growers need new sustainable pest control solutions. We selected four putative allelochemicals with known fungicidal and herbicidal activity (ferulic acid, gallic acid, juglone, and p-Coumaric acid). We assessed the pesticidal activity …

Game Theory Analysis Of Intra-District Water Transfers; Case Study Of The Berrenda Mesa Water District, Harry Riordan Ferdon

Master's Theses

California state officials have continued to warn and encourage preparedness for the growing threats of water scarcity. This puts pressure on water suppliers to develop technological and managerial solutions to alleviate the problems associated with scarcity. A recent popular management strategy for distributing water is encouraging water transfers. While there has been analyses on water transfers between large districts and agencies, little analysis has been completed for smaller scale trades, i.e. between individuals in the same water district. This analysis models an agricultural water district, based on the Berrenda Mesa Water District (BMWD). In the model, the growers in the …

Behavioral Determinants Of Biofortified Food Acceptance: The Case Of Orange-Fleshed Sweet Potato In Ghana, Chinonso E. Etumnu

Master's Theses

Biofortified foods are being introduced in sub-Saharan Africa as an important strategy to help address micronutrient malnutrition. However, there has been little research on factors that could play decisive roles in their successful introduction. This paper investigates the determinants of consumer acceptance of biofortified orange-fleshed sweet potato (OFSP) using data from a choice experiment conducted in Ghana. I find that OFSP is preferred to traditional white-fleshed and yellow-fleshed sweet potatoes as indicated by consumers' marginal willingness to pay for the three varieties. I also find that respondents' socio-economic characteristics do not have a significant effect on consumer acceptance of OFSP. …

Predicting Invasive Range Of Eucalyptus Globulus In California, Anthony J. Lopez

Master's Theses

Eucalyptus globulus is the subject of intense debate in California. Its invasive potential, aggressive growth, reproductive biology, and association with fire make the prediction of spread important in California. Two modeling simulations, Climex and Maxent, will illustrate the distribution and potential growth range of E. globulus in California based on climate and presence. Modeling the potential range of growth will predict invasive spread. The anticipated result is the continued spread of E. globulus in coastal regions with adequate moisture and suitable climate. Predicting the range of E. globulus in California dictates management strategy and is key for preventing further introduction, …